SlideShare a Scribd company logo
1 of 12
© 2004 WebMD, Inc. All rights reserved.                                                                  ACS Surgery: Principles and Practice
6 VASCULAR SYSTEM                                                                           2 ASYMPTOMATIC CAROTID BRUIT — 1



2 ASYMPTOMATIC CAROTID BRUIT
Claudio S. Cinà, M.D., Sp.Chir. (It.), M.Sc., F.R.C.S.(C), Catherine M. Clase, M.B., B.Chir., M.Sc.,
and Aleksandar Radan, M.D., B.Sc., B.F.A.




Assessment of Asymptomatic Carotid Bruit

The term bruit refers to any noise detected on auscultation in the           hours or causes death.9 Amaurosis fugax is a transient (< 24 hours)
neck.The conventional method of auscultation is to use the bell of           loss of vision in one eye or a portion of the visual field.9 If a patient
the stethoscope and listen over an area extending from the upper             with a carotid bruit has a history of any of these conditions in the ip-
end of the thyroid cartilage to just below the angle of the jaw.1-3 The      silateral eye or brain, then the bruit is regarded as neurologically
principal reason why bruits in the neck are matters of some concern          symptomatic, and the relevant question at that point is whether the
is that they may reflect underlying occlusive carotid artery disease,        patient has significant carotid stenosis and may be a candidate for
which carries an increased risk of stroke.                                   carotid endarterectomy on that basis. Given the substantial differ-
    In what follows, we outline a problem-oriented approach to the           ences between the management of patients with symptomatic bruits
workup of patients found to have cervical bruits at the time of rou-         and those with asymptomatic bruits, the distinction between these
tine or focused vascular examination.                                        two patient groups is crucial.
                                                                                The history is of critical importance in the diagnosis of TIA be-
Clinical Evaluation                                                          cause most TIAs last less than 4 hours,10 which means that patients
                                                                             typically are not seen by physicians during the period of neurologic
                                                                             deficit.11 Patients should be specifically asked about transient focal
CAROTID BRUITS VERSUS
                                                                             problems with vision, language, facial paresis, dysarthria, and arm
OTHER CERVICAL SOUNDS
                                                                             or leg numbness or weakness. A 1984 study reported good interob-
   Clinical assessment begins                                                server agreement (κ = 0.65) [see Table 1] between clinicians diagnos-
with evaluation of the character                                             ing previous ischemic episodes.12 Assigning a probable neurologic
of the bruit and examination of                                              territory to a TIA or stroke, however, proved more difficult: for TIAs,
the precordium and the cervical                                              the interobserver agreement between two independent neurologists
structures. Carotid bruits must be distinguished from other sounds           asked to distinguish between carotid and vertebrobasilar events was
heard in the neck.Venous hums are relatively common, being report-           relatively poor (κ = 0.31).12 There is some evidence that using a stan-
ed in 27% of young adults.4 They tend to have a diastolic compo-             dardized protocol for the diagnosis of previous ischemic episodes
nent, are louder when the patient sits or turns the head away from           might improve this low interobserver agreement (e.g., to κ = 0.6512
the side of auscultation, and disappear when the patient lies down           or κ = 0.7713). Similar difficulties attend diagnosis of stroke by means
or when the Valsalva maneuver is performed.4 Ejection systolic mur-          of history and physical examination.14
murs of cardiac origin may radiate into the neck, but generally, they           Many patients with a possible TIA or stroke will have undergone
are bilateral, are louder within the chest, and are less audible distal-     neurologic imaging. Such imaging is unhelpful if it yields negative
ly in the neck5; the same is true of bruits arising in other intratho-       results; however, in some cases, it reveals the presence of an infarct,
racic vessels.6,7 No definitive clinical sign has yet been identified that   thereby confirming the ischemic nature of the event and establish-
clearly differentiates bruits from transmitted cardiac murmurs. On
occasion, a bruit may be heard over the thyroid gland; however, this
finding is extremely rare and is usually accompanied by thy-
                                                                              Table 1          Quantification of Interobserver Agreement*
romegaly and other features of autoimmune thyroid disease.5 In
dialysis patients, a bruit may be generated by the increased flow re-                               κ†                                 Strength of Agreement
sulting from the creation of an arteriovenous fistula in the forearm.8
                                                                                                 ≤ 0.2                                           Poor
SYMPTOMATIC VERSUS ASYMP-                                                                     > 0.2, ≤ 0.4                                        Fair
TOMATIC CAROTID BRUITS                                                                        > 0.4, ≤ 0.6                                     Moderate
                                                                                              > 0.6, ≤ 0.8                                       Good
   Transient ischemic attacks                                                                  > 0.8, ≤ 1                                      Very good
(TIAs) are defined as brief epi-
sodes of focal loss of brain func-                                           *Reliability (how closely an assessment agrees with another similar assessment on a
                                                                             second occasion or by a second observer) and validity (how closely the assessment
tion that can usually be localized                                           agrees with another criterion or a gold standard) are the key properties of any assess-
                                                                             ment. When agreement between two observers is poor, the assessment in question,
to a specific portion of the brain                                           whether it is a physical finding, a clinical diagnosis, or an interpretation of a diagnostic
supplied by a single vascular sys-                                           test, is lacking in reliability; if more reliable methods are available, they should be consid-
                                                                             ered instead. In clinical medicine, however, more reliable methods are not always avail-
tem.9 By arbitrary convention,                                               able. When this is the case, the physician must use a relatively unreliable assessment as
such an ischemic episode is considered a TIA if it lasts less than 24        the best available alternative, while remaining aware of its limitations.118
                                                                             †
                                                                              κ is a statistical measure used to quantify agreement between two or more observers.
hours; a similar episode, in the absence of evidence of trauma or hem-       It takes a value between 0 and 1, where 0 represents agreement no better than that
orrhage, is considered an ischemic stroke if it lasts more than 24           expected by chance alone and 1 represents perfect agreement.118
© 2004 WebMD, Inc. All rights reserved.                                                      ACS Surgery: Principles and Practice
6 VASCULAR SYSTEM                                                                  2 ASYMPTOMATIC CAROTID BRUIT — 2



                                                                                               Noise is detected on auscultation
                                                                                               of neck

                                                                                               Determine nature of cervical sound.




                     Sound is carotid bruit

                     Distinguish symptomatic bruits from asymptomatic bruits;
                     the decision affects treatment.




                  Bruit is symptomatic                                 Bruit is asymptomatic

                                                                       Perform vascular risk assessment, looking for vascular
                                                                       risk factors (e.g., ↑BP, ↑lipids, diabetes, smoking) and
                                                                       vascular disease (e.g., ischemic cardiac disease,
                                                                       peripheral vascular disease).
                                                                       Initiate modification of vascular risk. Determine subsequent
                                                                       management approach.




Assessment of                                                                              Risk associated with CE is low
                                                                                           (Goldman class I or II)
Asymptomatic Carotid Bruit                                                                  Assess risk of carotid stenosis.




                                                                   Risk of carotid stenosis is high                Risk of carotid
                                                                                                                   stenosis is low
                                                                   Risk factors include ↑age, ↑BP, smoking,
                                                                   peripheral vascular disease.
                                                                   Assess risk of stroke.




                                              Risk of stroke is high                                          Risk of stroke is low

                                           Risk factors include age > 70, male sex, ↑BP, ↑lipids,
                                           diabetes, smoking, ischemic cardiac disease,
                                           peripheral vascular disease.
                                           Consult patient preferences regarding surgical treatment.




                            Patient prefers surgical management                            Patient prefers medical management

                             Determine presence and degree of carotid stenosis
                             with duplex ultrasonography and carotid angiography.




         Severe stenosis is present               Moderate stenosis is present                           Minimal or no stenosis
                                                                                                         is present
         Perform prophylactic CE.                 Reevaluate with duplex ultrasonography
                                                  every 1– 2 yr unless patient status
                                                  changes.
© 2004 WebMD, Inc. All rights reserved.                                                       ACS Surgery: Principles and Practice
6 VASCULAR SYSTEM                                                                   2 ASYMPTOMATIC CAROTID BRUIT — 3




                              Sound is venous hum, radiating cardiac
                              murmur or intrathoracic bruit, or thyroid bruit




          Patient is to be assessed as candidate for               Patient is to be managed
          carotid endarterectomy (CE)                              conservatively


         Determine level of risk associated with procedure.




               Risk associated with CE is
               high (Goldman class ≥ III)




                                          Continue modification of vascular risk.
                                          Educate patient regarding symptoms and
                                          signs of stroke.
                                          Carry out nonsurgical follow-up.
                                          Re-refer patient promptly if he or she ever
                                          becomes symptomatic.
© 2004 WebMD, Inc. All rights reserved.                                                                 ACS Surgery: Principles and Practice
6 VASCULAR SYSTEM                                                                          2 ASYMPTOMATIC CAROTID BRUIT — 4


ing its location. For a bruit to be regarded as symptomatic on the                              Table 2          Annual Risk of Stroke
basis of imaging studies, at least one infarct must be seen in the ap-
propriate ipsilateral anterior vasculature.                                                    Patient Population                          Annual Risk of Stroke
   It is evident that distinguishing between symptomatic and asymp-
tomatic bruits on clinical grounds may be difficult; nonetheless, it          Population without bruits, age > 60 yr19,43,44              0.86% (95% CI, 0.8–0.9)
                                                                              Population with bruits, age > 60 yr19,20,43                 2.1% (95% CI, 0.6–8.5)
is worthwhile to make the effort because the risk of stroke in the
                                                                              Male population without bruits, age > 60 yr19,24            0.9% (95% CI, 0.1–3.0)
asymptomatic population is quite different from that in the sympto-           Male population with bruits, age > 60 yr19                  8.0% (95% CI, 0.2–38.0)
matic population. For example, whereas the Asymptomatic Carotid               Female population without bruits, age > 60 yr24             2.0% (95% CI, 0.8–4.2)
Atherosclerosis Study (ACAS), which included patients believed on             Female population with bruits, age > 60 yr19                2.4% (95% CI, 0.7–5.5)
clinical grounds to be neurologically asymptomatic, reported an
overall stroke rate of 6.2% at 2.7 years in its medically managed
group,15 the North American Symptomatic Carotid Endarterecto-                gestive heart failure, or peripheral vascular syndrome) will occur in the
my Trial (NASCET), which included patients assessed as neurolog-             next 5 years is greater than 20%.22,37 In such patients, consultation
ically symptomatic (i.e., with a history of amaurosis fugax,TIA, or          of formulas or tables is unnecessary, and all modifiable risk factors
minor stroke), reported a stroke rate of 26% at 3 years in its med-          should be aggressively managed (target BP < 140/90; target ratio of
ically managed group.16                                                      total cholesterol to high-density lipoprotein [HDL] cholesterol < 4).22
   In determining whether a unilateral bruit is symptomatic or                  A meta-analysis of randomized, controlled trials showed that as-
asymptomatic, the physician should concentrate primarily on is-              pirin reduced the risk of subsequent stroke, MI, and death from vas-
chemic deficits in the ipsilateral hemisphere (i.e., those causing focal     cular events for patients who had previously experienced a cere-
contralateral motor or sensory deficits) and ipsilateral amaurosis fu-       brovascular event, MI, or unstable angina.38 Other meta-analyses of
gax. However, symptoms referable to the contralateral carotid ar-            randomized, controlled trials39,40 were unable to confirm the effec-
tery, even if no bruit is heard on that side, might prompt evaluation        tiveness of aspirin in preventing cerebrovascular events in asympto-
of the patient for symptomatic carotid stenosis on the contralateral         matic patients or in patients with TIAs or strokes of noncardiac (and
side.The absence of a bruit by no means excludes the diagnosis: ca-          presumably vascular) origin41; however, one randomized, controlled
rotid bruits are absent in 20% to 35% of patients with high-grade            trial involving hypertensive patients at modest vascular risk found
stenosis of the internal carotid artery.17 In the NASCET subgroup            that aspirin reduced the risk of vascular events, if not the risk of
in which the physical finding of a carotid bruit was compared with           stroke.42 In the absence of contraindications, we recommend that as-
angiographic imaging of the carotid system, the presence of a focal          pirin be considered for all patients who have established vascular dis-
ipsilateral carotid bruit had a sensitivity of 63% and a specificity of      ease elsewhere and for all patients who have a bruit in association
61% for high-grade (70% to 99%) stenosis; the absence of a bruit             with any vascular risk factors.
did not significantly change the probability of significant stenosis in      INDICATIONS FOR SURGICAL
this population (pretest 52%, posttest 40%).18                               INTERVENTION
   Workup of patients with symptomatic bruits is beyond the scope
of this chapter. Accordingly, the ensuing discussion focuses on as-             The absolute risk of stroke is
sessment of patients with asymptomatic bruits.                               increased in the presence of a ca-
                                                                             rotid bruit. In population-based
VASCULAR RISK ASSESSMENT                                                     studies, the annual risk of stroke
   Vascular diseases and other vascular risk factors are common in           was 2.1% (95% confidence in-
patients with asymptomatic carotid bruits. Hypertension is twice as          terval [CI], 0.6 to 8.5)19,20,43,44
common in patients who have bruits as in those who do not19;                 for persons who had a carotid
smoking, ischemic heart disease, and peripheral vascular disease are         bruit and 0.86% (95% CI, 0.8 to 0.9) for those who did not.19,43,44
also more prevalent.20,21 Consequently, detection of a bruit should          These figures represent an absolute risk increase for stroke of 1.24%
prompt a thorough vascular risk assessment. Standard vascular risk           a year and a relative risk for stroke of 2.4. The mean patient age in
factors—hypertension, hyperlipidemia, diabetes, and smoking—can              these studies was approximately 65 years, and sex distribution and
be integrated into risk profiles for particular patients by using either     prevalence of risk factors for atherosclerotic disease were similar in
the New Zealand risk tables (http://www.nzgg.org.nz/library/gl_              patients with bruits and those without bruits. Even after adjustment
complete/bloodpressure/appendix.cfm) or the formula and spread-              for age, sex, and the presence of hypertension, the presence of a ca-
sheets provided by Anderson et al.22,23 The probability of stroke for        rotid bruit remained an independently significant variable, with a
various follow-up periods may be quantified by using the Framing-            relative risk of 2.0.19
ham stroke-risk profile.24 From age, systolic blood pressure, dia-
betes, smoking, cardiovascular disease, atrial fibrillation, and left ven-    Table 3         Prevalence of Carotid Stenosis in Patients
tricular hypertrophy, probability of stroke may be calculated for men                       with Bruits and in Healthy Volunteers
and women according to a point system.24
   Smoking cessation should be recommended to all patients,25-27                          Patient Population                    Prevalence of Carotid Stenosis
and hypertension should be controlled (BP < 140/90).28-31 De-
pending on a patient’s individual risk profile, dietary and pharma-           Overall population with cervical bruits
cologic management of hyperlipidemia may also be warranted.32-34               > 35% stenosis20,56-58,119                       58% (95% CI, 55–60)
Diabetic control should be optimized.35,36                                     > 60%–75% stenosis56-58                          21% (95% CI, 18–24)
   Patients should be asked specifically about any concurrent vascu-          Healthy volunteers*
lar disease—in particular, symptoms suggestive of ischemic heart dis-          Age > 70 yr89                                    5.1% (95% CI, 2.6–9.0)
ease or of claudication or rest pain. In patients with established vascu-      Age ≤ 70 yr89                                    1.5% (95% CI, 0.2–5.3)
lar disease, the risk that future vascular events (e.g., coronary-related    *In healthy volunteers, the incidence of asymptomatic carotid stenosis is significantly
death, myocardial infarction [MI], new angina, stroke,TIA, new con-          correlated with age (P < 0.01) and with the presence of hypertension (P < 0.005).
© 2004 WebMD, Inc. All rights reserved.                                                       ACS Surgery: Principles and Practice
6 VASCULAR SYSTEM                                                                    2 ASYMPTOMATIC CAROTID BRUIT — 5


                                                                          nonfatal MI was 2% (95% CI, 1.1 to 3.9), whereas for patients in
          Table 4 Necessary Criteria for Offering                         class III or IV, the corresponding figure was 21% (95% CI, 9.2 to
           an Interventional Approach to Selected                         39.9) [see Table 5]. Given that 50 prophylactic carotid endarterec-
                                                                          tomies would have to be performed to prevent one stroke over the
                 Patients with Carotid Bruits
                                                                          subsequent 3-year period (i.e., the number needed to treat [NNT]
   Center-specific criteria                                               is 50), it is clearly unacceptable to perform this procedure in a pop-
    Either                                                                ulation facing a 21% incidence of MI or death, in which for every 5
    DUS is documented to have a > 90% PPV for stenosis > 50% on           patients undergoing the operation, one would experience an MI or
      angiography and is used alone
                                                                          die (i.e., the number needed to harm [NNH] is only 5). Further
    or
                                                                          consideration of prophylactic carotid endarterectomy in patients for
    DUS has a lower PPV and is used as a screening test only, and
      angiography in patients with cerebrovascular disease has a          whom the procedure carries a high risk is not warranted.
      documented complication (stroke or death) rate of around 1%
   Surgeon-specific criterion                                               High Risk of Carotid Stenosis
    Perioperative rate of stroke or death is < 3% for carotid                Cohort45,54-60 and population-
      endarterectomy
                                                                          based19,61,62 studies suggest that
   DUS—duplex ultrasonography   PPV—positive predictive value             patients with asymptomatic ca-
                                                                          rotid bruits are more likely to
                                                                          have significant carotid stenosis
   Given the low absolute risk of stroke in asymptomatic patients         if they are older, are hyperten-
with bruits [see Table 2], the low prevalence of surgically relevant      sive, smoke, or have advanced
stenosis in patients with bruits [see Table 3], and the small (and        peripheral vascular disease. In
only marginally statistically significant) absolute benefit of carotid    one study, hemodynamically significant stenosis (i.e., > 50%) was
endarterectomy in patients with asymptomatic stenosis,45,46 we            found by means of ultrasonography in 32% of patients scheduled to
and others47-51 do not believe that further investigation with a view     undergo peripheral vascular procedures but in only 6.8% of those
to carotid endarterectomy is mandatory in the asymptomatic pop-           scheduled to undergo coronary artery bypass grafting (CABG).63
ulation. Many surgeons may prefer to manage these patients con-           (All figures for degree of stenosis in this chapter are determined ac-
servatively, reevaluating them promptly if they become sympto-            cording to the formula used in NASCET [see Table 6 and Figure 1].)
matic [see Discussion, below]. Other surgeons may wish to pursue             Further consideration of carotid endarterectomy may be war-
a more interventional strategy with selected patients, in which case      ranted in patients with vascular risk factors or known peripheral
further evaluation with an eye to surgical treatment depends on           vascular disease; in the absence of these findings, the risk of signifi-
the presence of the following key findings in a given patient: (1)        cant carotid stenosis is low. Further evaluation is unnecessary for
low risk associated with carotid endarterectomy, (2) relatively high      patients who are younger, do not smoke, are not hypertensive or di-
risk of carotid stenosis, and (3) high risk of stroke if carotid steno-   abetic, and are not known to have peripheral vascular disease.
sis is documented. In addition, the patient’s preferences should be
consulted: no patient should be subjected to further evaluation who         High Risk of Stroke
is not prepared to undergo surgical treatment if such management             Within the group of patients
is recommended. Patients who, on the basis of any of these crite-         with asymptomatic carotid ste-
ria, are not suitable candidates for intervention will not benefit        nosis, there is only limited direct
from imaging studies and should be managed medically.                     evidence for the existence of sub-
   Finally, surgeons and centers who are contemplating offering           groups of patients at higher risk
prophylactic carotid endarterectomy for asymptomatic stenosis             for stroke. Men seem to be at
should be able to document that their rates of stroke or periopera-       higher risk for stroke than wom-
tive death for this procedure are lower than 3% [see Table 4].When        en are: in the medical arm of
complication rates exceed this threshold, the value of carotid endar-     ACAS, the incidence of stroke or death at 2.7 years was 7.0% (95%
terectomy becomes negligible, and surgeons may find themselves            CI, 4.9 to 9.4) for men and 4.9% (95% CI, 2.7 to 8.0) for women.
doing more harm than good.45,46                                           Gender-related differences aside, however, identification of other
                                                                          subgroups at higher risk relies on extrapolation of data from other
  Low Risk Associated with                                                populations at risk for artery-to-artery embolism. Data from
  Carotid Endarterectomy                                                  NASCET indicate that for symptomatic patients with greater than
   In NASCET and ACAS, pa-                                                70% carotid stenosis, the presence of a higher number of identifi-
tients were excluded if they had                                          able clinical risk factors (age > 70 years; male sex; systolic or dias-
coexisting medical disease likely                                         tolic hypertension; the occurrence of a cerebrovascular event within
to produce significant mortality                                          the preceding 31 days; the occurrence of a more serious cerebrovas-
and morbidity (e.g., cardiac val-                                         cular event, namely, stroke rather than a TIA or amaurosis fugax;
vular or rhythm disorders, un-                                            smoking; MI; congestive heart failure; diabetes; intermittent claudi-
controlled hypertension or dia-                                           cation; or hyperlipidemia) was associated with a higher annual
betes, unstable angina pectoris, or MI in the previous 4 months)16;       stroke risk. For patients with zero to three risk factors, the annual
accordingly, the results of these trials are not generalizable to pa-     stroke risk was 6.6%; for those with four or five, 9.2%; and for those
tients who have such conditions. Further evidence for the impact of       with six or more, 15.8%. Data from the same study indicate that
operative risk on outcomes is provided by a retrospective review of       among patients with a contralateral asymptomatic stenosed carotid
562 patients who underwent carotid endarterectomy for sympto-             artery, patients with zero to three risk factors have an annual stroke
matic and asymptomatic disease in a large community hospital.52           risk of 1.4% in the territory of the asymptomatic stenosis; those
For patients in Goldman class I or II,53 the overall rate of death or     with four or five, 2.8%; and those with six or more, 3.8%.64
© 2004 WebMD, Inc. All rights reserved.                                                                   ACS Surgery: Principles and Practice
6 VASCULAR SYSTEM                                                                            2 ASYMPTOMATIC CAROTID BRUIT — 6


   Obesity is another risk factor for stroke.49,50 Some 60% of pa-                           Table 5           Cardiac Risk Assessment*
tients who experience a stroke before 65 years of age have a body
mass index greater than 24 kg/m2.49 This finding, in conjunction                                                          Weighted Score on Cardiac Risk Index
with a history of smoking, was found to predict 60% of strokes in                           Parameter
men in this age group.50                                                                                                      Goldman               Detsky          Eagle
   Patients with carotid bruits who do not have significant systemic           Age > 70 yr                                         5                    5               1
risk factors or other vascular disease are at low absolute risk for
stroke and are unlikely to benefit from carotid endarterectomy;                MI                                                                                       1
hence, further investigation is not warranted.5,18,49 Patients with nu-         < 6 mo                                            10                    10
merous (i.e., six or more) clinical risk factors [see Table 7] are at rela-     > 6 mo                                                                  5
tively high risk for stroke, and it is in this population that most of the     Angina                                                                                   1
benefit from carotid endarterectomy is likely to be concentrated.               Class III                                                               10
                                                                                Class IV                                                                20
  Patient Preference for Surgical                                               Unstable                                                                10
  Intervention
                                                                               Diabetes                                                                                 1
   Before pursuing the diagno-
sis of carotid stenosis with im-                                               Operation
                                                                                Emergency                                          4                    10
aging techniques, the surgeon
                                                                                Aortic, abdominal, or thoracic                     3
must discuss prophylactic sur-
gical intervention with the pa-                                                CHF                                                11                                    1
tient. The essential question is,                                               < 1 wk                                                                  10
if significant stenosis is docu-                                                > 1 wk                                                                  5
mented, will the patient wish to undergo carotid endarterectomy?               ECG
It should be remembered that at this point in the workup, we are                Rhythm other than sinus                            7                    5
considering only those patients (1) for whom the cardiac risk                   > 5 PVCs/min                                       7                    5
associated with the procedure is acceptably low and (2) who are
                                                                               Poor medical status†                                3                    5
considered to be at relatively high risk for stroke if carotid steno-
sis is demonstrated.
                                                                               Risk of Perioperative Cardiac Events
   Patients should be informed that if they are found to have signifi-
cant carotid stenosis, their risk of stroke is 6.3% over the ensuing           Low                                        0–12 (class I, II)        0–15               0
2.7 years if they do not undergo operation and 4.0% over the same              Intermediate                               13–25 (class III)         16–30             1–2
period if they do.15 They should also be informed that these figures           High                                       > 25 (class IV)            > 30             ≥3
take into account a 3% risk of perioperative stroke or death (2.7%
                                                                              *The Goldman cardiac risk index53 is a multifactorial index of cardiac risk in patients under-
risk of stroke and 0.3% risk of death).15 The 2.3% absolute risk re-          going noncardiac surgery. Modifications have been proposed by Detsky,121-123 who includ-
duction associated with surgical treatment translates into an NNT             ed angina and institution-specific perioperative cardiac event rates in the model. The Eagle
                                                                              index124-126 is another risk index based on five clinical variables. Despite the lack of con-
of 43, meaning that 43 patients would have to undergo endarterec-             sensus regarding the relative merits of these tools for preoperative cardiac risk assessment,
                                                                              stratification of patients into risk categories is helpful in assessing the risk and benefits of a
tomy to prevent one stroke over the next 2.7 years.                           procedure such as carotid endarterectomy.
   Given the front-loaded risks of surgery, some patients will prefer         †
                                                                               PaO2 < 60 mm Hg; PaCO2 > 50 mm Hg; K+ < 3 mmol/L; serum HCO3 < 20 mmol/L; serum
                                                                              urea > 18 mmol/L; creatinine > 260 µmol/L; abnormal ALT; signs of chronic liver disease;
a simple risk-modification strategy to a strategy including both risk         bedridden from cardiac causes.
modification and surgical intervention. In such cases, carotid imag-          CHF—congestive heart failure MI—myocardial infarction PVC—premature ventricular
                                                                              contraction
ing is not necessary, because knowledge of the degree of stenosis
will not affect subsequent management.
                                                                              than 50% stenosis (determined by means of angiography, the gold
                                                                              standard), DUS had a sensitivity of 91% (95% CI, 89 to 94) and a
Investigative Studies                                                         specificity of 93% (95% CI, 88 to 95).67 Given a disease prevalence
   The purpose of investigation                                               of approximately 41% in patients referred for DUS, these findings
of asymptomatic neck bruits is to                                             translate into a positive predictive value of 90% and an accuracy of
identify persons with significant                                             92%.67 A subsequent prospective study of patients (both sympto-
carotid stenosis who are at in-                                               matic and asymptomatic) in whom carotid endarterectomy was being
creased risk for cerebrovascular                                              considered reported a sensitivity of 100% and a specificity of 98% for
disease65,66 and who are likely to                                            greater than 60% stenosis, with a positive predictive value of 99%.68
benefit from carotid endarterec-                                                 At centers where DUS has been internally validated in com-
tomy. In the absence of other sig-                                            parison with angiography and where this level of performance
nificant findings, cervical bruits are not sufficiently predictive of sig-    has been documented, the surgeons may choose to proceed to
nificant carotid stenosis or ischemic stroke to be useful in selecting        surgery without angiography.68-70 At centers where DUS is less
candidates for noninvasive imaging.51 Noninvasive testing is a rea-           reliable, however, it should be regarded as a screening test, and
sonable step in patients with the characteristics listed above, but           angiography should be performed when DUS suggests greater
routine screening of all patients with asymptomatic carotid bruits is         than 50% stenosis.
not warranted.51
                                                                              CAROTID ANGIOGRAPHY
DUPLEX ULTRASONOGRAPHY
                                                                                 As an invasive procedure, carotid angiography carries a significant
 Duplex ultrasonography (DUS) should be performed bilaterally.A               risk of morbidity and mortality. All centers performing carotid an-
meta-analysis conducted in 1995 found that for detecting greater              giography for cerebrovascular disease should audit their stroke rates
© 2004 WebMD, Inc. All rights reserved.                                                                              ACS Surgery: Principles and Practice
6 VASCULAR SYSTEM                                                                                        2 ASYMPTOMATIC CAROTID BRUIT — 7


                                  Table 6          Conversion between Different Methods of Measuring
                                                          Degree of Carotid Stenosis
                                                                                        Severity of Disease
                           Method
                                                   Minimal                         Moderate                          Severe              Occlusion

                        ECST*                     24%–57%                58%–69%              70%–81%               82%–99%                 100%
                        NASCET                     0%–29%                30%–49%              50%–69%               70%–99%                 100%
                                 †
                        CC method                 35%–56%                57%–61%              62%–80%               81%–99%                 100%

                    *Conversion from ECST to NASCET was done according to the following formula: ECST % stenosis = 0.6(NASCET % stenosis) + 40.127
                    †
                     The relation of the NASCET method to the CC method is linear, with a ratio of 0.62 between the distal internal carotid diameter and
                    the common carotid diameter.117


periodically. Since 1990, four prospective studies71-74 have addressed                    greater degrees of stenosis would be associated with greater risk of
the question of the risks associated with angiography in patients with                    stroke.This finding may be explained either by the fact that duplex
atherosclerotic cerebrovascular disease. When the data from these                         ultrasound was the sole imaging criterion or that plaque morpholo-
studies were pooled, the risk of permanent neurologic deficit or death                    gy plays a greater role in determining stroke risk than degree of ste-
was 1.1% (95% CI, 0.6 to 2.0).75 In ACAS, the 1.2% of patients in                         nosis. Furthermore, unlike previous studies, many of the patients in
the intervention arm who experienced stroke or died after angiogra-                       the ACST were receiving lipid-lowering drugs and other antiplatelet
phy accounted for 40% of the strokes and deaths attributable to sur-                      agents. As Barnett pointed out in his discussion of the ACST article,
gical intervention.15 Angiographic complication rates significantly                       the perioperative stroke rate must be low for the results of this study
worse than these will adversely impact the risk-benefit ratio associat-                   to be generalized.81 In the ACST, the risk of stroke or death within
ed with surgical intervention. Centers that consistently record rela-                     30 days of undergoing carotid endarterectomy was 3.1%.
tively high angiographic complication rates should not offer evalua-                         Technical details of carotid endarterectomy are discussed else-
tion for and surgical treatment of asymptomatic carotid disease.                          where [see 6:9 Surgical Treatment of Carotid Artery Disease].
                                                                                          PATIENT EDUCATION
Management
                                                                                             All patients with asymptomatic carotid bruits, whether they are
CAROTID ENDARTERECTOMY
                                                                                          undergoing prophylactic endarterectomy or not, should be carefully
   At this point in management, it is reasonable to offer surgical treat-                 advised regarding the symptoms and signs of stroke, TIAs, and
ment of asymptomatic disease to patients with greater than 50% ste-                       amaurosis fugax and should be strongly encouraged to seek urgent
nosis. ACAS15 and two meta-analyses45,46 that included other trials of                    medical attention if such problems arise. Patients who experience
surgical therapy for asymptomatic carotid stenosis documented a                           one of these untoward events should undergo full reevaluation for
small and marginally statistically significant benefit from prophylactic                  stroke risk factors (e.g., hypertension, hyperlipidemia, diabetes, smok-
carotid endarterectomy in asymptomatic patients with greater than                         ing, and atrial fibrillation); in the absence of atrial fibrillation (which
50% to 60% carotid stenosis. Because the absolute benefit is small,
we do not consider it obligatory to pursue the diagnosis or to follow                                  Internal
an invasive strategy in patients identified solely on the basis of an                                Carotid Artery
asymptomatic bruit; however, patients possessing all the characteris-                                                                      External
                                                                                                                                           Carotid Artery
tics listed earlier [see Indications for Surgical Intervention, above]
probably constitute a group that is particularly able to benefit from
                                                                                                            B
surgical intervention. Patients with higher degrees of stenosis are at
higher risk for stroke and are therefore most likely to benefit.76-79
   The degree of stenosis and the presence or absence of plaque ul-                                                                        ECST Method
ceration may modify the final decision for or against operative man-                                                                                C–A
                                                                                                                                                        x 100% Stenosis
agement [see Discussion, Subgroup Analyses for Potential High-                                                                                       C
                                                                                                            A
Risk Factors, below].
   In May 2004, the United Kingdom Medical Research Council                                                C                               NASCET Method
Asymptomatic Carotid Surgery Trial (ACST) collaborative group                                                                                       B–A
                                                                                                                                                        x 100% Stenosis
reported the results of a prospective, randomized trial of carotid                                                                                   B
endarterectomy in asymptomatic patients.80 More than 3,000 pa-
tients were randomly assigned either to undergo immediate carotid                                          D                               CC Method
endarterectomy or to be placed on indefinite deferral. In the patients
                                                                                                                                                    D–A
referred for immediate carotid endarterectomy, one half underwent                                                                                    D
                                                                                                                                                        x 100% Stenosis
endarterectomy within 1 month of referral; 88% underwent endar-
terectomy within 1 year. Combining the rate of perioperative events                                  Common
                                                                                                    Carotid Artery
and nonperioperative strokes, the 5-year results indicate a stroke rate
of 6.4% in the group undergoing immediate carotid endarterecto-
                                                                                          Figure 1 Carotid angiography remains the gold standard for de-
my, as compared with 11.8% in the deferral group.These findings                           termining the extent of carotid arterial disease. Several methods
are strikingly similar to the ACAS findings. However, the ACST                            of reporting angiographically defined stenosis have been described
found a similar benefit for women. In addition, in the ACST, no dif-                      in the literature.115 The most commonly used methods are those
ference was found in the degree of stenosis and the benefit of                            adopted by the NASCET and ECST investigators, though the so-
surgery—an interesting observation, because one would expect that                         called common carotid (CC) method has its advocates as well.116,117
© 2004 WebMD, Inc. All rights reserved.                                                            ACS Surgery: Principles and Practice
6 VASCULAR SYSTEM                                                                        2 ASYMPTOMATIC CAROTID BRUIT — 8


                                                                              ter a stroke.75 Performing endarterectomy early reduces the risk pe-
             Table 7         Risk Factors for Stroke128,129                   riod for recurrent stroke and may therefore increase the potential
                                                                              benefit of the intervention; the usual approach is to perform the
         Age > 70 yr                        Smoking (or history of smoking)   procedure within a week or two of a patient’s first neurologic event.
         Male sex                           > 80% carotid stenosis               Management of cardiovascular risk factors and concurrent vascu-
         Hypertension*                      Presence of ulceration
                                                                              lar disease should continue. In the absence of concurrent vascular
         Hyperlipidemia                     Ischemic heart disease†
                                                                              disease, patients may be referred back to the family practitioner, in-
         Diabetes                           Peripheral vascular disease
                                                                              ternist, or cardiologist in place of specific surgical follow-up.
   *Defined as systolic BP > 160 mm Hg or diastolic BP > 90 mm Hg.
   †
    MI or CHF.                                                                FOLLOW-UP OF PATIENTS WITH LOWER-GRADE STENOSIS

                                                                                 Carotid stenosis progresses in about one quarter of patients with
                                                                              asymptomatic carotid stenosis monitored with DUS over a 2-year
should prompt consideration of prophylactic anticoagulation82-84), a          period.87 In a population of asymptomatic patients with bruits who
change in antiplatelet therapy should be considered. Both ticlopi-            were referred to a vascular laboratory, 282 stenotic carotid arteries
dine85 and clopidogrel86 are more effective than aspirin in preventing        (average stenosis, 50%) were followed for 38 ± 18 months. Progres-
stroke. (Ticlopidine is associated with reversible but severe neutro-         sion of stenosis, defined as an increase in degree of stenosis to 80%
penia in fewer than 1% of cases; accordingly, monitoring for this             or beyond, occurred in 17% of arteries, and 2% became complete-
complication is indicated.)                                                   ly occluded. Progression was associated with an increase in stroke
   If a patient who is a surgical candidate experiences a TIA or              risk of 4.9% at 1 year, 16.7% at 3 years, and 26.5% at 5 years. In
stroke as a result of an ischemic event in the carotid region in the          comparison, the estimated stroke risk in an asymptomatic popula-
absence of atrial fibrillation, he or she must be promptly referred           tion of patients with 50% to 79% stenosis was 0.85%, 3.6%, and
back to the vascular surgeon.This possibility should be clearly ex-           5.4% for the same three periods (P = 0.001).76
plained to patients once the initial evaluation is complete and they             Although carotid stenosis, once identified, tends to progress over
have been referred back to their primary care physicians. Patients            time,20,54,76,88 the data are currently insufficient to permit recommenda-
referred back to a vascular surgeon under these circumstances                 tion of routine ultrasonographic or other surveillance for all patients
should then be regarded as having symptomatic carotid disease. A              with neck bruits outside a research setting. In our view, reevaluation
subgroup analysis of patients with symptomatic stenosis reported              every 1 to 2 years with noninvasive diagnostic tests is a reasonable ap-
that carotid endarterectomy performed soon after a nondisabling               proach to patients (1) who are already known to have greater than 50%
stroke was not associated with a significantly higher operative com-          stenosis, (2) who do not undergo surgery, and (3) who are at high risk
plication rate than endarterectomy performed 30 days or longer af-            for stroke, are surgical candidates, and are not averse to surgery.




Discussion
Epidemiology                                                                  Economic Considerations
   In cross-sectional and population-based studies, the overall prev-            A cogent argument in favor of pursuing a surgical strategy in at
alence of greater than 75% carotid stenosis has been low. A 1992              least some patients was made by a 1997 economic analysis,90 which
study reported a 2.3% prevalence in men and a 1.1% prevalence in              demonstrated that although prophylactic endarterectomy in patients
women; there was a significant (P < 0.0001) increase with age with            with asymptomatic carotid stenosis did not reduce societal costs ap-
each decade from 65 years to beyond 85 years, but there were no               preciably, it was nonetheless, at a cost of $8,000/quality-adjusted life
significant differences between men and women.62 In the Framing-              year (QALY), within the range of many interventions considered by
ham study population, the incidence of greater than 50% stenosis              society to be cost-effective. It should be pointed out, however, that
was 8% (95% CI, 6.5 to 9.8).61 In a study of healthy volunteers, the          this economic analysis addressed only carotid endarterectomy in pa-
incidence of greater than 50% stenosis was 5.1% (95% CI, 2.6 to               tients with identified carotid stenosis, not screening strategies for pa-
9.0) in patients 70 years of age or older and 1.5% (95% CI, 0.2 to            tients with bruits, and consequently did not consider costs associat-
5.3) in younger patients.89                                                   ed with investigation and follow-up to the point of recommendation
   The pooled risk of greater than 60% to 75% stenosis in patients            for or against carotid endarterectomy in the broader group of pa-
with carotid bruits referred for noninvasive vascular evaluation at an        tients with bruits.These costs would alter the economic analysis sub-
average age of 65 years is reported to be 21% (95% CI, 18 to 24),56-58        stantially, and if they are included, it is far from clear whether the re-
which is three to four times the prevalence expected on the basis of          sulting overall cost/QALY would still be acceptable.To date, no trial
population-based studies.Thus, five persons with neck bruits must             or economic analysis of a screening strategy has been published.
be screened to detect one patient with moderate to severe carotid
stenosis.The absolute benefit of surgery is small and of borderline           Screening Issues
statistical significance. In ACAS, as noted (see above), the relative
risk reduction for an ipsilateral major stroke or perioperative death            For the reasons previously discussed, we do not feel justified in
over a 2.7-year period was 36.5% (95% CI, 27.5 to 47.1), the abso-            recommending routine screening for patients with asymptomatic
lute risk reduction was 2.3% (95% CI, 0.2 to 7.0), and the NNT                carotid bruits. Given the available evidence, we believe that such pa-
was 43 (95% CI, 14 to 500); the number of patients that would have            tients may reasonably be managed in either of two ways. One
to be screened with DUS to prevent one stroke over a 3-year follow-           choice is simply to conclude that screening patients with carotid
up period was 250 (95% CI, 70 to 2,500).                                      bruits as possible candidates for carotid endarterectomy has not
© 2004 WebMD, Inc. All rights reserved.                                                              ACS Surgery: Principles and Practice
6 VASCULAR SYSTEM                                                                          2 ASYMPTOMATIC CAROTID BRUIT — 9

                                                                                PLAQUE ULCERATION AND PLAQUE STRUCTURE
been proved to be a useful intervention and to concentrate instead
on general vascular risk reduction.The other, which is appropriate                  At present, there are no subgroup analyses examining the effect
in centers where noninvasive or invasive diagnostic tests reach ac-             of plaque ulceration on the ability of asymptomatic patients to ben-
ceptable standards with an acceptable degree of risk and where the              efit from surgical treatment. In NASCET, however, when sympto-
procedure is done by surgeons whose documented perioperative                    matic patients with 70% to 99% stenosis were considered, those
stroke and death rates are less than 3%, is to take a selective ap-             with angiographic evidence of plaque ulceration were at higher risk
proach that addresses various issues related to stroke risk, cardiac            for stroke than those without ulceration92 and derived greater bene-
risk, and patient preferences before noninvasive tests are ordered.             fit from surgery.75 Angiography had a sensitivity of 46% and a speci-
                                                                                ficity of 74% in the detection of ulcerated plaques, with a positive
                                                                                predictive value of 72%.93 A 1994 study reported that when ulcera-
Subgroup Analyses for Potential High-Risk Factors
                                                                                tion was detected with B-mode imaging in patients with asympto-
   Given the small absolute risk reduction reported by ACAS15                   matic carotid stenosis, the incidence of silent cerebral infarction de-
and by the two meta-analyses of all asymptomatic carotid stenosis               tected by magnetic resonance imaging was 75%, compared with an
trials,45,46 it would be useful to be able to identify one or more              incidence of 25% when ulceration was absent.94
high-risk groups within the broader group of patients identified as                 It has also been suggested that carotid plaques of differing struc-
having stenosis.                                                                tures may have differing embolic potentials.95 DUS can distinguish
                                                                                between fibrous plaques (which are highly echogenic) and plaques
SEX
                                                                                with high concentrations of lipid and necrotic material (which are
   ACAS included a subgroup analysis addressing the effect of sex               echolucent). Echolucent plaques are more frequently associated
on ability to benefit from surgery: the absolute reduction in the risk          with neurologic symptoms and computed tomography–proven ce-
of perioperative stroke or death or ipsilateral stroke at 2.7 years was         rebral infarction.95-97 Interobserver reliability for plaque echostruc-
3.6% (95% CI, 1.1 to 9.9) for men and 0.5% (95% CI, 0.01 to 2.7)                ture, however, seems to be highly variable, ranging from good (κ =
for women.                                                                      0.79) for greater than 70% stenosis95 to average (κ = 0.51) for
                                                                                greater than 40% stenosis98 to poor (κ = 0.29) for greater than 80%
DEGREE OF STENOSIS
                                                                                stenosis.99 A 1994 report found no correlation between the pres-
   In asymptomatic patients stratified according to their ultrasono-            ence or type of symptoms and plaque structure as determined by
graphically determined degree of stenosis, the risk of stroke is low            DUS.100 The true importance of carotid plaque echomorphology
both for patients with less than 30% stenosis (4% cumulative event              and surface characteristics as predictors of cerebrovascular events
rate at 3 years) and for those with 30% to 74% stenosis (9% cumu-               remains to be defined.
lative event rate at 3 years); it is highest for those with greater than
                                                                                CONTRALATERAL DISEASE
75% stenosis (21% cumulative event rate at 3 years).20 The Euro-
pean Carotid Surgery Trialists (ECST) study,47 using angiographic                  It has been suggested that the presence of contralateral carotid dis-
data from the asymptomatic carotid arteries of 2,295 patients, re-              ease is a risk factor for future cerebrovascular events. In NASCET pa-
ported that the Kaplan-Meyer estimate of stroke risk at 3 years was             tients with greater than 70% stenosis,101 contralateral occlusion signif-
only 2% and remained low (< 2%) when patients with less than                    icantly increased the benefit of surgery with respect to the incidence
79% stenosis were considered; stroke risk increased to 9.8% for pa-             of stroke or death, but contralateral high-grade stenosis did not.75
tients with 70% to 79% stenosis and to 14.4% for those with 80%
                                                                                ASYMPTOMATIC CEREBRAL INFARCTION
to 99% stenosis. In a population of patients referred to a vascular
laboratory with asymptomatic carotid stenosis on DUS who were                      The presence of areas of asymptomatic cerebral infarction ipsilat-
followed for a mean of 38 months, the incidence of stroke was 2.1%              eral to the area of carotid stenosis on head CT may identify patients
in patients with 50% to 79% stenosis and 10.4% in those with great-             who would benefit from surgery.102 In asymptomatic patients with
er than 80% stenosis.76                                                         carotid stenosis, the incidence of silent strokes demonstrated by CT
   In ACAS, there were too few strokes to permit subgroup analysis              has been reported to be 10% in patients with 35% to 50% stenosis
of the effect of degree of stenosis on ability to benefit from carotid          on DUS, 17% in those with 50% to 75% stenosis, and 30% in
endarterectomy. In both ECST79 and NASCET,75,77,78,91 however,                  those with greater than 75% stenosis.103 The incidence of silent
higher degrees of stenosis in symptomatic patients were consistent-             cerebral infarctions demonstrated by MRI in the same type of pop-
ly observed to be associated with higher stroke risk as well as with            ulation has been reported to be 42%, increasing to 75% for greater
greater ability to benefit from surgical treatment [see Table 8].               than 50% stenosis.94 Use of CT and MRI of the brain in risk strati-




                       Table 8        Effectiveness of Surgery by Degree of Stenosis in Patients with
                                                 Symptomatic Carotid Stenosis75
                    Degree              Relative Risk Reduction            Absolute Risk Reduction          Number Needed to Treat
                  of Stenosis                 or Increase                        or Increase                      or Harm

                    70%–99%            RRR, 48% (95% CI, 27–63)           ARR, 6.7% (95% CI, 3.2–10)        NNT, 15 (95% CI, 10–31)
                    50%–69%            RRR, 27% (95% CI, 5–44)            ARR, 4.7% (95% CI, 0.8–8.7)       NNT, 21 (95% CI, 11–125)
                      ≤ 49%             RRI, 20% (95% CI, 0–44)            ARI, 2.2% (95% CI, 0–4.4)        NNH, 45 (95% CI, 22–∝)

              ARI—absolute risk increase ARR—absolute risk reduction   NNH—number needed to harm   NNT—number needed to treat
              RRI—relative risk increase RRR—relative risk reduction
© 2004 WebMD, Inc. All rights reserved.                                                                               ACS Surgery: Principles and Practice
6 VASCULAR SYSTEM                                                                                       2 ASYMPTOMATIC CAROTID BRUIT — 10


fication of patients with asymptomatic carotid stenosis is controver-                       CI, 2.1 to 4.5), the MI rate is 5.2% (95% CI, 3.6 to 6.9)—a non-
sial and currently is not advised.                                                          significant increase—and the mortality is 4.7% (95% CI, 3.4 to
                                                                                            6.4).109 For cohorts in which CABG was done first and carotid ste-
CONCLUSIONS
                                                                                            nosis was treated on its own after the cardiac procedure, the stroke
   Although only limited data on patients with asymptomatic steno-                          rate is 3.5% (95% CI, 1.0 to 9.0), the MI rate is 2% (95% CI, 0.2 to
sis are available, we believe that consideration of sex, degree of steno-                   6.0), and the mortality is 0.8% (95% CI, 0.02 to 4.8).110-112
sis, and possibly the presence of plaque ulceration may be helpful in                          We recommend against a combined surgical approach in patients
making the final decision on whether to offer carotid endarterecto-                         with asymptomatic carotid stenosis. Given the equivalent stroke rate
my to these patients; at present, plaque morphology is insufficiently                       and the lower MI rate and mortality, we believe that the preferred
reliable to be a useful guide to clinical management.                                       strategy in patients with bruits is first to proceed with CABG if indi-
                                                                                            cated and then to determine whether the patient should be further
Special Situations                                                                          evaluated as a candidate for carotid endarterectomy in the same
                                                                                            manner as other elective patients would be.
RESTENOSIS OR PREVIOUS CAROTID SURGERY

   Patients who have previously undergone carotid surgery have                              Effect of Center-Specific Variations on Risk-to-Benefit Ratio
been excluded from most studies of asymptomatic patients; when
they have been included in trials addressing symptomatic stenosis,                             In ACAS, 1.2% of the overall 2.7% perioperative stroke rate was
they have experienced increased rates of perioperative complica-                            accounted for by strokes occurring after angiography. Centers where
tions.16,50 Patients in whom restenosis occurs after an earlier carot-                      ultrasonography has been documented to have high predictive val-
id endarterectomy should be advised against surgery while they                              ues may avoid this risk by proceeding directly from ultrasonography
remain asymptomatic.15 It is therefore unnecessary to follow pa-                            to surgery. If these complications had been avoided in ACAS, the
tients with ultrasonography after carotid endarterectomy if no                              absolute risk reduction would have been more substantial: 3.43%
symptoms develop.                                                                           (95% CI, 1.1 to 9.9), corresponding to an NNT of 29 (95% CI, 1
                                                                                            to 80). The true perioperative combined stroke and death rate
PREOPERATIVE ASSESSMENT FOR CORONARY ARTERY BYPASS
                                                                                            achieved in this study was 1.5%, a result that is definitive of excel-
GRAFTING
                                                                                            lence in the surgical management of carotid endarterectomy and
   Some 20% to 30% of patients undergoing assessment for CABG                               that constitutes a useful quality assurance measure for centers and
are found to have carotid bruits,49,104 and 5% to 20% have greater                          individual surgeons.
than 50% stenosis on DUS105-107 or ocular plethysmography.108 In
asymptomatic patients with carotid stenosis who are undergoing                              Issues for the Future
CABG, there is no direct evidence favoring prophylactic carotid
endarterectomy either before or in conjunction with CABG. Co-                                  It is possible, perhaps likely, that in the future, magnetic reso-
hort studies including symptomatic and asymptomatic carotid ste-                            nance angiography67 and three-dimensional CT angiography,113,114
nosis indicate that patients undergoing CABG and carotid endarter-                          together with DUS, will replace angiography as preferred imaging
ectomy in the same operation have a stroke rate of 6% (95% CI, 4.6                          methods for diagnosing internal carotid artery stenosis. As for surgi-
to 7.8), an MI rate of 4.6% (95% CI, 3.1 to 6.5), and a mortality of                        cal treatment and screening, further data on patients with asympto-
4.7% (95% CI, 3.4 to 6.4).109 For cohorts in which carotid endarter-                        matic carotid stenosis are necessary before definitive recommenda-
ectomy was performed before CABG, the stroke rate is 3.2% (95%                              tions can be made.


References

  1. Chambers BR, Norris JW: Clinical significance of             Cerebrovascular Diseases III. Stroke 21:637, 1990            tomy Trial Collaborators (NASCET): Beneficial ef-
     asymptomatic neck bruits. Neurology 35:742, 1985        10. Werdelin L, Juhler M:The course of transient ische-           fect of carotid endarterectomy in symptomatic pa-
  2. Harrison MJ: Cervical bruits and asymptomatic ca-           mic attacks. Neurology 38:677, 1988                           tients with high-grade carotid stenosis. N Engl J Med
     rotid stenosis. Br J Hosp Med 32:80, 1984                                                                                 325:445, 1991
                                                             11. Albers GW, Hart RG, Lutsep HL, et al: AHA Scien-
  3. Ratcheson RA: Clinical diagnosis of atherosclerotic                                                                  17. Davies KN, Humphrey PRD: Do carotid bruits pre-
                                                                 tific Statement. Supplement to the guidelines for the
     carotid artery disease. Clin Neurosurg 29:464, 1982                                                                      dict disease of the internal carotid arteries? Postgrad
                                                                 management of transient ischemic attacks: a state-
                                                                                                                              Med J 70:433, 1994
  4. Jones FL: Frequency, characteristics and importance         ment from the Ad Hoc Committee on Guidelines for
                                                                 the Management of Transient Ischemic Attacks,            18. Sauve JS,Thorpe KE, Sackett DL, et al: Can bruits
     of the cervical venous hum in adults. N Engl J Med
                                                                 Stroke Council, American Heart Association. Stroke           distinguish high-grade from moderate symptomatic
     267:658, 1962
                                                                 30:2502, 1999                                                carotid stenosis? The North American Symptomatic
  5. Sauve JS, Laupacis A, Ostbye T, et al: Does this pa-                                                                     Carotid Endarterectomy Trial. Ann Intern Med 120:
     tient have a clinically important carotid bruit? JAMA   12. Kraaijeveld CL, van Gijn J, Schouten HJ, et al: Inter-       633, 1994
     270:2843, 1993                                              observer agreement for the diagnosis of transient is-
                                                                 chemic attacks. Stroke 15:723, 1984                      19. Heyman A, Wilkinson WE, Heyden S, et al: Risk of
  6. Caplan LR: Carotid artery disease. N Engl J Med                                                                          stroke in asymptomatic persons with cervical arterial
     315:886, 1986                                           13. Koudstaal PJ, van Gijn J, Staal A, et al: Diagnosis of       bruits: a population study in Evans County, Georgia.
                                                                 transient ischemic attacks: improvement of inter-            N Engl J Med 302:838, 1980
  7. Thompson JE, Patman RD,Talkington CM: Asymp-
                                                                 observer agreement by a check-list in ordinary lan-
     tomatic carotid bruit: long term outcome of patients                                                                 20. Chambers BR, Norris JW: Outcome in patients with
     having endarterectomy compared with unoperated              guage. Stroke 17:723, 1986
                                                                                                                              asymptomatic neck bruits. N Engl J Med 315:860,
     controls. Ann Surg 188:308, 1978                        14. von Arbin M, Britton M, de Faire U, et al:Validation         1986
  8. Messert B, Marra TR, Zerofsky RA: Supraclavicular           of admission criteria to a stroke unit. J Chronic Dis
                                                                                                                          21. Meissner I,Wiebers DO,Whisnant JP, et al:The nat-
     and carotid bruits in hemodialysis patients. Ann Neu-       33:215, 1980
                                                                                                                              ural history of asymptomatic carotid artery occlusive
     rol 2:535, 1977                                         15. Toole JF, Baker WH, Castaldo JE, et al: Endarterecto-        lesions. JAMA 258:2704, 1987
  9. National Institute of Neurological Disorders and            my for asymptomatic carotid artery stenosis. JAMA        22. Anderson KM, Odell PM,Wilson PW, et al: Cardio-
     Stroke: Special Report from the National Institute of       273:1421, 1995                                               vascular disease risk profiles. Am Heart J 121(1 pt 2):
     Neurological Disorders and Stroke. Classification of    16. North American Symptomatic Carotid Endarterec-               293, 1991
© 2004 WebMD, Inc. All rights reserved.                                                                                     ACS Surgery: Principles and Practice
6 VASCULAR SYSTEM                                                                                             2 ASYMPTOMATIC CAROTID BRUIT — 11


23. Anderson KM,Wilson PW, Odell PM, et al: An up-                   domised trial. HOT Study Group. Lancet 351:1755,                rotic disease of the aortic arch and the risk of is-
    dated coronary risk profile: a statement for health              1988                                                            chemic stroke. N Engl J Med 331:1474, 1994
    professionals. Circulation 83:356, 1991                     43. Wiebers DO, Whisnant JP, Sandok BA, et al: Pro-             67. Blakeley DD, Oddone EZ, Hasselblad V, et al: Non-
24. Wolf PA, D’Agostino RB, Belanger AJ, et al: Proba-              spective comparison of a cohort with asymptomatic               invasive carotid artery testing: a meta-analytic review.
    bility of stroke: a risk profile from the Framingham            carotid bruit and a population-based cohort without             Ann Intern Med 122:360, 1997
    Study. Stroke 22:312, 1991                                      carotid bruit. Stroke 21:984, 1990                          68. Ballotta E, DaGiau G, Abbruzzese E, et al: Carotid
25. Wolf PA, D’Agostino RB, Kannel WB, et al: Cigarette         44. Shorr RI, Johnson KC,Wan JY, et al:The prognostic               endarterectomy without angiography: can clinical
    smoking as a risk factor for stroke.The Framingham              significance of asymptomatic carotid bruits in the el-          evaluation and duplex ultrasonographic scanning
    Study. JAMA 259:1025, 1988                                      derly. J Gen Intern Med 13:86, 1998                             alone replace traditional arteriography for carotid
26. Wannamethee SG, Shaper AG, Whincup PH, et al:               45. Benavente OR, Moher D, Pham B: Carotid endarter-                surgery workup? A prospective study. Surgery 126:
    Smoking cessation and the risk of stroke in middle-             ectomy for asymptomatic carotid stenosis: a meta-               20, 1999
    aged men. JAMA 274:155, 1995                                    analysis. BMJ 317:1477, 1998                                69. Wolf RK, Williams EL II, Kistler PC: Transbrachial
27. Shinton R, Beevers G: Meta-analysis of relation be-         46. Chambers BR,You RX, Donnan GA: Carotid endar-                   balloon catheter tamponade of ruptured abdominal
    tween cigarette smoking and stroke. BMJ 298:789,                terectomy for asymptomatic carotid stenosis. Coch-              aortic aneurysms without fluoroscopic control. Surg
    1989                                                            rane Database Syst Rev (2):CD001923, 2000                       Gynecol Obstet 164:463, 1987
28. Prevention of stroke by antihypertensive drug treat-        47. European Carotid Surgery Trialists’ Collaborative           70. Baird RN: Should carotid endarterectomy be pur-
    ment in older persons with isolated systolic hyperten-          Group: Risk of stroke in the distribution of an asymp-          chased? treatment avoids much morbidity. BMJ 310:
    sion: final results of the Systolic Hypertension in the         tomatic carotid artery. Lancet 345:209, 1995                    316, 1995
    Elderly Program (SHEP). SHEP Cooperative Re-                                                                                71. Hankey GJ, Warlow CP, Molyneux AJ: Complica-
                                                                48. Gorelick PB: Carotid endarterectomy: where do we
    search Group. JAMA 265:3255, 1991                                                                                               tions of cerebral angiography for patients with mild
                                                                    draw the line? (editorial) Stroke 30:1745, 1999
29. Sutton-Tyrrell K, Alcorn HG, Herzog H, et al: Mor-                                                                              carotid territory ischaemia being considered for ca-
                                                                49. Gorelick PB, Sacco RL, Smith DB, et al: Prevention              rotid endarterectomy. J Neurol Neurosurg Psychiatry
    bidity, mortality, and antihypertensive treatment ef-
                                                                    of a first stroke: a review of guidelines and a multidis-       53:542, 1990
    fects by extent of atherosclerosis in older adults with
                                                                    ciplinary consensus statement from the National
    isolated systolic hypertension. Stroke 26:1319, 1995                                                                        72. Heiserman JE, Dean BL, Hodak JA, et al: Neurolog-
                                                                    Stroke Association. JAMA 281:1112, 1999
30. Sutton-Tyrrell K, Wolfson SK Jr, Kuller LH: Blood                                                                               ic complications of cerebral angiography. AJNR Am J
                                                                50. Feinberg RW: Primary and secondary stroke preven-               Neuroradiol 15:1401, 1994
    pressure treatment slows the progression of carotid
                                                                    tion. Curr Opin Neurol 9:46, 1996
    stenosis in patients with isolated systolic hyperten-                                                                       73. Davies KN, Humphrey PR: Complications of cere-
    sion. Stroke 25:44, 1994                                    51. Lee TT, Solomon NA, Heidenreich PA, et al: Cost-                bral angiography in patients with symptomatic carot-
                                                                    effectiveness of screening for carotid stenosis in asymp-       id territory ischaemia screened by carotid ultrasound.
31. Collins R, Peto R, MacMahon S, et al: Blood pres-
                                                                    tomatic persons. Ann Intern Med 126:337, 1997
    sure, stroke, and coronary heart disease. Part 2, Short-                                                                        J Neurol Neurosurg Psychiatry 56:967, 1993
    term reductions in blood pressure: overview of ran-         52. Musser DJ, Nicholas GG, Reed JF III: Death and
                                                                                                                                74. Grzyska J, Freitag J, Zeumer H: Selective cerebral in-
    domised drug trials in their epidemiological context.           adverse cardiac events after carotid endarterectomy.
                                                                                                                                    traarterial DSA: Complication rate and control of
    Lancet 335:827, 1990                                            J Vasc Surg 19:615, 1994
                                                                                                                                    risk factors. Neuroradiology 32:296, 1990
32. Randomised trial of cholesterol lowering in 4444 pa-        53. Goldman L, Caldera DL, Nussbaum SR, et al: Mul-
                                                                                                                                75. Cinà CS, Clase CM, Haynes RB: Refining indi-
    tients with coronary heart disease: the Scandinavian            tifactorial index of cardiac risk in noncardiac surgical
                                                                                                                                    cations for carotid endarterectomy in patients with
    Simvastatin Survival Study (4S). Lancet 344:1383,               procedures. N Engl J Med 297:845, 1977
                                                                                                                                    symptomatic carotid stenosis: a systematic review.
    1994                                                        54. Roederer GO, LangloisYE, Jager KA, et al:The natu-              J Vasc Surg 30:606, 1999
33. Furberg CD: Lipid-lowering trials: results and limita-          ral history of carotid arterial disease in asymptomatic
                                                                                                                                76. Rockman CB, Riles TS, Lamparello PJ, et al: Natural
    tions. Am Heart J 128(6 pt 2):1304, 1994                        patients with cervical bruits. Stroke 15:605, 1984
                                                                                                                                    history and management of the asymptomatic, mod-
34. Furberg CD, Adams HP Jr, Applegate WB, et al: Ef-           55. Fowl RJ, Marsh JG, Love M, et al: Prevalence of he-             erately stenotic internal carotid artery. J Vasc Surg
    fect of lovastatin on early carotid atherosclerosis and         modynamically significant stenosis of the carotid ar-           25:423, 1997
    cardiovascular events. Asymptomatic Carotid Artery              tery in an asymptomatic veteran population. Surg
                                                                                                                                77. Cina CS, Clase CM, Haynes RB: Carotid endarte-
    Progression Study (ACAPS) Research Group. Circu-                Gynecol Obstet 172:13, 1991
                                                                                                                                    rectomy for symptomatic carotid stenosis. Cochrane
    lation 90:1679, 1994                                        56. Zhu CZ, Norris JW: Role of carotid stenosis in is-              Database Syst Rev (2):CD001081, 2000
35. The effect of intensive treatment of diabetes on the            chemic stroke. Stroke 21:1131, 1990
                                                                                                                                78. Rothwell PM, Slattery J,Warlow CP: Clinical and an-
    development and progression of long-term complica-          57. AbuRahma AF, Robinson PA: Prospective clinico-                  giographic predictors of stroke and death from carotid
    tions in insulin-dependent diabetes mellitus.The Di-            pathophysiologic follow-up study of asymptomatic                endarterectomy: systematic review. BMJ 315:1571,
    abetes Control and Complications Trial Research                 neck bruit. Am Surg 56:108, 1990                                1997
    Group. N Engl J Med 329:977, 1993
                                                                58. Lusiani L,Visonà A, Castellani V, et al: Prevalence of      79. European Carotid Surgery Trialists’ Collaborative
36. Intensive blood-glucose control with sulphonyl-ureas            atherosclerotic lesions at the carotid bifurcation in pa-       Group: Randomized trial of endarterectomy for re-
    or insulin compared with conventional treatment                 tients with asymptomatic bruits: an echo-Doppler                cently symptomatic carotid stenosis: final results of
    and risk of complications in patients with type 2 dia-          (duplex) study. Angiology 36:235, 1985                          the MRC European Carotid Surgery Trial. Lancet
    betes (UKPDS 33). UK Prospective Diabetes Study
                                                                59. Kartchner MM, McRae LP: Noninvasive evaluation                  351:1379, 1998
    (UKPDS) Group [published erratum appears in
    Lancet 354:602, 1999]. Lancet 352:837, 1998                     and management of the “asymptomatic” carotid                80. Halliday A, Mansfield A, Marro J, et al: Prevention of
                                                                    bruit. Surgery 82:840, 1977                                     disabling and fatal strokes by successful carotid end-
37. Anderson KM,Wilson PW, Odell PM, et al: An up-
                                                                60. Clagett GP,Youkey JR, Brigham RA, et al: Asympto-               arterectomy in patients without recent neurological
    dated coronary risk profile: a statement for health
                                                                    matic cervical bruit and abnormal ocular pneumo-                symptoms: randomised controlled trial. MRC
    professionals. Circulation 83:356, 1991
                                                                    plethysmography: a prospective study comparing two              Asymptomatic Carotid Surgery Trial (ACST) Col-
38. Collaborative overview of randomised trials of anti-            approaches to management. Surgery 96:823, 1984                  laborative Group. Lancet 363:1491, 2004
    platelet therapy—I. Prevention of death, myocardial
                                                                61. Wilson PWF, Hoeg JM, D’Agostino RB, et al: Cu-              81. Barnett JHM: Commentary: Carotid endarterecto-
    infarction, and stroke by prolonged antiplatelet thera-
                                                                    mulative effects of high cholesterol levels, high blood         my. Lancet 363:1486, 2004
    py in various categories of patients. Antiplatelet Trial-
    ists’ Collaboration [published erratum appears in               pressure, and cigarette smoking on carotid stenosis.        82. Stroke Prevention in Atrial Fibrillation Study: Final
    BMJ 308:1540, 1994]. BMJ 308:81, 1994                           N Engl J Med 337:516, 1997                                      results. Circulation 84:527, 1991
39. Hart RG, Halperin JL, McBride R, et al: Aspirin for         62. O’Leary DH, Polak JF, Kronmal RA, et al: Distribu-          83. Warfarin versus aspirin for prevention of thrombo-
    the primary prevention of stroke and other major vas-           tion and correlates of sonographically detected carot-          embolism in atrial fibrillation: Stroke Prevention in
    cular events: meta-analysis and hypotheses. Arch                id artery disease in the Cardiovascular Health Study.           Atrial Fibrillation II Study. Lancet 343:687, 1994
    Neurol 57:326, 2000                                             The CHS Collaborative Research Group. Stroke
                                                                    23:1752, 1992                                               84. Go AS, Hylek EM, Phillips KA, et al: Implications of
40. Kronmal RA, Hart RG, Manolio TA, et al: Aspirin                                                                                 stroke risk criteria on the anticoagulation decision in
    use and incident stroke in the cardiovascular health        63. Hennerici M, Aulich A, Sandmann W, et al: Inci-                 nonvalvular atrial fibrillation: the Anticoagulation and
    study. CHS Collaborative Research Group. Stroke                 dence of asymptomatic extracranial arterial disease.            Risk Factors in Atrial Fibrillation (ATRIA) study.
    29:887, 1998                                                    Stroke 12:750, 1981                                             Circulation 102:11, 2000
41. Barnett HJM, Eliasziw M, Meldrum HE: Drugs and              64. Barnett HJ, Eliasziw M, Meldrum HE, et al: Do the           85. Hass WK, Easton JD, Adams HP Jr, et al: A random-
    surgery in the prevention of ischemic stroke. N Engl J          facts and figures warrant a 10-fold increase in the             ized trial comparing ticlopidine hydrochloride with
    Med 332:238, 1995                                               performance of carotid endarterectomy on asympto-               aspirin for the prevention of stroke in high-risk pa-
                                                                    matic patients? Neurology 46:603, 1996                          tients. Ticlopidine Aspirin Stroke Study Group. N
42. Hansson L, Zanchetti A, Carruthers SG, et al: Effects
    of intensive blood-pressure lowering and low-dose as-       65. Warlow C: Endarterectomy for asymptomatic carotid               Engl J Med 321:501, 1989
    pirin in patients with hypertension: principal results of       stenosis? Lancet 345:1254, 1995                             86. Creager MA: Results of the CAPRIE trial: efficacy
    the Hypertension Optimal Treatment (HOT) ran-               66. Amarenco P, Cohen A,Tzourio C, et al: Atheroscle-               and safety of clopidogrel. Clopidogrel versus aspirin
Acs0602 Asymptomatic Carotid Bruit

More Related Content

What's hot

ARRHYTHMOGENIC RIGHT VENTRICULAR DYSPLASIA/CARDIOMYOPATHY
ARRHYTHMOGENIC  RIGHT VENTRICULAR DYSPLASIA/CARDIOMYOPATHYARRHYTHMOGENIC  RIGHT VENTRICULAR DYSPLASIA/CARDIOMYOPATHY
ARRHYTHMOGENIC RIGHT VENTRICULAR DYSPLASIA/CARDIOMYOPATHYSR,CARDIOLOGY,JIPMER,PUDUCHERRY
 
2007 terni, corso sulla medicina basata sull'evidenza. l'arresto cardiaco int...
2007 terni, corso sulla medicina basata sull'evidenza. l'arresto cardiaco int...2007 terni, corso sulla medicina basata sull'evidenza. l'arresto cardiaco int...
2007 terni, corso sulla medicina basata sull'evidenza. l'arresto cardiaco int...Centro Diagnostico Nardi
 
Arvd vs uhls anomaly
Arvd vs uhls anomalyArvd vs uhls anomaly
Arvd vs uhls anomalyNilesh Tawade
 
ACC 2011 research highlights: A slideshow presentation
ACC 2011 research highlights: A slideshow presentation ACC 2011 research highlights: A slideshow presentation
ACC 2011 research highlights: A slideshow presentation theheart.org
 
Intracranial atherosclerotic disease
Intracranial atherosclerotic diseaseIntracranial atherosclerotic disease
Intracranial atherosclerotic diseaseNeurologyKota
 
2007 rieti, convegno regionale, quale terapia nelle channelopatie
2007 rieti, convegno regionale, quale terapia nelle channelopatie2007 rieti, convegno regionale, quale terapia nelle channelopatie
2007 rieti, convegno regionale, quale terapia nelle channelopatieCentro Diagnostico Nardi
 
ECG changes in anorexia nervosa
ECG changes in anorexia nervosaECG changes in anorexia nervosa
ECG changes in anorexia nervosaSimon Daley
 
Acs0619 Endovascular Procedures For Lower Extremity Disease
Acs0619 Endovascular Procedures For Lower Extremity DiseaseAcs0619 Endovascular Procedures For Lower Extremity Disease
Acs0619 Endovascular Procedures For Lower Extremity Diseasemedbookonline
 
Management of premature ventricular complexes
Management of premature ventricular complexesManagement of premature ventricular complexes
Management of premature ventricular complexesRamachandra Barik
 
1362466122 pad in diabetes
1362466122 pad in diabetes1362466122 pad in diabetes
1362466122 pad in diabetesdfsimedia
 
Small vessel disease: Evolving concept
Small vessel disease: Evolving conceptSmall vessel disease: Evolving concept
Small vessel disease: Evolving conceptErsifa Fatimah
 
Endovascular Coil Embolization of Dissecting distal MCA Aneurysm with ICH in ...
Endovascular Coil Embolization of Dissecting distal MCA Aneurysm with ICH in ...Endovascular Coil Embolization of Dissecting distal MCA Aneurysm with ICH in ...
Endovascular Coil Embolization of Dissecting distal MCA Aneurysm with ICH in ...Dr. Shahnawaz Alam
 
IFR - Instantenous wave free ratio
IFR - Instantenous wave free ratioIFR - Instantenous wave free ratio
IFR - Instantenous wave free ratioVishal Vanani
 
Prognostic value of noninvasive testing after orthotopic cardiac transplantation
Prognostic value of noninvasive testing after orthotopic cardiac transplantationPrognostic value of noninvasive testing after orthotopic cardiac transplantation
Prognostic value of noninvasive testing after orthotopic cardiac transplantationPatrick P Verhoeven
 
Children at very low risk of brain injuries
Children at very low risk of brain injuriesChildren at very low risk of brain injuries
Children at very low risk of brain injuriesSun Yai-Cheng
 
AHA 2010 research highlights: A slideshow presentation
AHA 2010 research highlights: A slideshow presentation AHA 2010 research highlights: A slideshow presentation
AHA 2010 research highlights: A slideshow presentation theheart.org
 
Arvd - dr prithvi puwar
Arvd - dr prithvi puwarArvd - dr prithvi puwar
Arvd - dr prithvi puwarPrithvi Puwar
 

What's hot (20)

ARRHYTHMOGENIC RIGHT VENTRICULAR DYSPLASIA/CARDIOMYOPATHY
ARRHYTHMOGENIC  RIGHT VENTRICULAR DYSPLASIA/CARDIOMYOPATHYARRHYTHMOGENIC  RIGHT VENTRICULAR DYSPLASIA/CARDIOMYOPATHY
ARRHYTHMOGENIC RIGHT VENTRICULAR DYSPLASIA/CARDIOMYOPATHY
 
2007 terni, corso sulla medicina basata sull'evidenza. l'arresto cardiaco int...
2007 terni, corso sulla medicina basata sull'evidenza. l'arresto cardiaco int...2007 terni, corso sulla medicina basata sull'evidenza. l'arresto cardiaco int...
2007 terni, corso sulla medicina basata sull'evidenza. l'arresto cardiaco int...
 
Arvd vs uhls anomaly
Arvd vs uhls anomalyArvd vs uhls anomaly
Arvd vs uhls anomaly
 
ACC 2011 research highlights: A slideshow presentation
ACC 2011 research highlights: A slideshow presentation ACC 2011 research highlights: A slideshow presentation
ACC 2011 research highlights: A slideshow presentation
 
Intracranial atherosclerotic disease
Intracranial atherosclerotic diseaseIntracranial atherosclerotic disease
Intracranial atherosclerotic disease
 
2007 rieti, convegno regionale, quale terapia nelle channelopatie
2007 rieti, convegno regionale, quale terapia nelle channelopatie2007 rieti, convegno regionale, quale terapia nelle channelopatie
2007 rieti, convegno regionale, quale terapia nelle channelopatie
 
ECG changes in anorexia nervosa
ECG changes in anorexia nervosaECG changes in anorexia nervosa
ECG changes in anorexia nervosa
 
Acs0619 Endovascular Procedures For Lower Extremity Disease
Acs0619 Endovascular Procedures For Lower Extremity DiseaseAcs0619 Endovascular Procedures For Lower Extremity Disease
Acs0619 Endovascular Procedures For Lower Extremity Disease
 
Management of premature ventricular complexes
Management of premature ventricular complexesManagement of premature ventricular complexes
Management of premature ventricular complexes
 
1362466122 pad in diabetes
1362466122 pad in diabetes1362466122 pad in diabetes
1362466122 pad in diabetes
 
Dedication-Clemmensen
Dedication-ClemmensenDedication-Clemmensen
Dedication-Clemmensen
 
Small vessel disease: Evolving concept
Small vessel disease: Evolving conceptSmall vessel disease: Evolving concept
Small vessel disease: Evolving concept
 
Endovascular Coil Embolization of Dissecting distal MCA Aneurysm with ICH in ...
Endovascular Coil Embolization of Dissecting distal MCA Aneurysm with ICH in ...Endovascular Coil Embolization of Dissecting distal MCA Aneurysm with ICH in ...
Endovascular Coil Embolization of Dissecting distal MCA Aneurysm with ICH in ...
 
IFR - Instantenous wave free ratio
IFR - Instantenous wave free ratioIFR - Instantenous wave free ratio
IFR - Instantenous wave free ratio
 
PCI & AimRadial 2018 | Lessons from iFR-SWEDEHEART and DEFINE-FLAIR - Hitoshi...
PCI & AimRadial 2018 | Lessons from iFR-SWEDEHEART and DEFINE-FLAIR - Hitoshi...PCI & AimRadial 2018 | Lessons from iFR-SWEDEHEART and DEFINE-FLAIR - Hitoshi...
PCI & AimRadial 2018 | Lessons from iFR-SWEDEHEART and DEFINE-FLAIR - Hitoshi...
 
Prognostic value of noninvasive testing after orthotopic cardiac transplantation
Prognostic value of noninvasive testing after orthotopic cardiac transplantationPrognostic value of noninvasive testing after orthotopic cardiac transplantation
Prognostic value of noninvasive testing after orthotopic cardiac transplantation
 
Children at very low risk of brain injuries
Children at very low risk of brain injuriesChildren at very low risk of brain injuries
Children at very low risk of brain injuries
 
AHA 2010 research highlights: A slideshow presentation
AHA 2010 research highlights: A slideshow presentation AHA 2010 research highlights: A slideshow presentation
AHA 2010 research highlights: A slideshow presentation
 
Arvd - dr prithvi puwar
Arvd - dr prithvi puwarArvd - dr prithvi puwar
Arvd - dr prithvi puwar
 
Hybrid concepts
Hybrid conceptsHybrid concepts
Hybrid concepts
 

Viewers also liked

Acs0601 Stroke And Transient Ischemic Attack
Acs0601 Stroke And Transient Ischemic AttackAcs0601 Stroke And Transient Ischemic Attack
Acs0601 Stroke And Transient Ischemic Attackmedbookonline
 
Acs0609 Surgical Treatment Of Carotid Artery Disease
Acs0609 Surgical Treatment Of Carotid Artery DiseaseAcs0609 Surgical Treatment Of Carotid Artery Disease
Acs0609 Surgical Treatment Of Carotid Artery Diseasemedbookonline
 
Acs0624 Raynaud Phenomenon
Acs0624 Raynaud PhenomenonAcs0624 Raynaud Phenomenon
Acs0624 Raynaud Phenomenonmedbookonline
 
Acs0603 Pulsatile Abdominal Mass
Acs0603 Pulsatile Abdominal MassAcs0603 Pulsatile Abdominal Mass
Acs0603 Pulsatile Abdominal Massmedbookonline
 
Acs0608 Fundamentals Of Endovascular Surgery
Acs0608 Fundamentals Of Endovascular SurgeryAcs0608 Fundamentals Of Endovascular Surgery
Acs0608 Fundamentals Of Endovascular Surgerymedbookonline
 
Acs0522 procedures for benign and malignant biliary tract disease-2005
Acs0522 procedures for benign and malignant biliary tract disease-2005Acs0522 procedures for benign and malignant biliary tract disease-2005
Acs0522 procedures for benign and malignant biliary tract disease-2005medbookonline
 

Viewers also liked (6)

Acs0601 Stroke And Transient Ischemic Attack
Acs0601 Stroke And Transient Ischemic AttackAcs0601 Stroke And Transient Ischemic Attack
Acs0601 Stroke And Transient Ischemic Attack
 
Acs0609 Surgical Treatment Of Carotid Artery Disease
Acs0609 Surgical Treatment Of Carotid Artery DiseaseAcs0609 Surgical Treatment Of Carotid Artery Disease
Acs0609 Surgical Treatment Of Carotid Artery Disease
 
Acs0624 Raynaud Phenomenon
Acs0624 Raynaud PhenomenonAcs0624 Raynaud Phenomenon
Acs0624 Raynaud Phenomenon
 
Acs0603 Pulsatile Abdominal Mass
Acs0603 Pulsatile Abdominal MassAcs0603 Pulsatile Abdominal Mass
Acs0603 Pulsatile Abdominal Mass
 
Acs0608 Fundamentals Of Endovascular Surgery
Acs0608 Fundamentals Of Endovascular SurgeryAcs0608 Fundamentals Of Endovascular Surgery
Acs0608 Fundamentals Of Endovascular Surgery
 
Acs0522 procedures for benign and malignant biliary tract disease-2005
Acs0522 procedures for benign and malignant biliary tract disease-2005Acs0522 procedures for benign and malignant biliary tract disease-2005
Acs0522 procedures for benign and malignant biliary tract disease-2005
 

Similar to Acs0602 Asymptomatic Carotid Bruit

Anesthesia for cerebral aneurysm repair
Anesthesia for cerebral aneurysm repairAnesthesia for cerebral aneurysm repair
Anesthesia for cerebral aneurysm repairDhritiman Chakrabarti
 
C.08a-Diagnosis-and-Treatment-of-Acute-Ischemic-Stroke-Presentation-ppt.pptx
C.08a-Diagnosis-and-Treatment-of-Acute-Ischemic-Stroke-Presentation-ppt.pptxC.08a-Diagnosis-and-Treatment-of-Acute-Ischemic-Stroke-Presentation-ppt.pptx
C.08a-Diagnosis-and-Treatment-of-Acute-Ischemic-Stroke-Presentation-ppt.pptxDrYaqoobBahar
 
Transient ischemic attacks
Transient ischemic attacksTransient ischemic attacks
Transient ischemic attacksNeurologyKota
 
Definition and Evaluation of Transient Ischemic Attack
Definition and Evaluation of Transient Ischemic AttackDefinition and Evaluation of Transient Ischemic Attack
Definition and Evaluation of Transient Ischemic AttackSun Yai-Cheng
 
Imaging techniques for myocardial hibernation
Imaging techniques for myocardial hibernationImaging techniques for myocardial hibernation
Imaging techniques for myocardial hibernationMichael Katz
 
Diagnosing Secondary
Diagnosing SecondaryDiagnosing Secondary
Diagnosing SecondaryMohamadAlhes
 
COMPUTATIONAL ASSESSMENT OF INTRA-CRANIAL ANEURYSM
COMPUTATIONAL ASSESSMENT OF INTRA-CRANIAL ANEURYSMCOMPUTATIONAL ASSESSMENT OF INTRA-CRANIAL ANEURYSM
COMPUTATIONAL ASSESSMENT OF INTRA-CRANIAL ANEURYSMguest629cef
 
Computational Fluid Dynamic Evaluation of Intra-Cranial Aneuryms
Computational Fluid Dynamic Evaluation of Intra-Cranial AneurymsComputational Fluid Dynamic Evaluation of Intra-Cranial Aneuryms
Computational Fluid Dynamic Evaluation of Intra-Cranial AneurymsChapman Arter
 
2D CFD simulation of intracranial aneurysm
2D CFD simulation of intracranial aneurysm2D CFD simulation of intracranial aneurysm
2D CFD simulation of intracranial aneurysmwalshb88
 
Transient ischaemic attacks mimics and chameleons
Transient ischaemic attacks mimics and chameleonsTransient ischaemic attacks mimics and chameleons
Transient ischaemic attacks mimics and chameleonsOlusola Adeyemi
 
Clinical And Echocardiographic Findings
Clinical And Echocardiographic FindingsClinical And Echocardiographic Findings
Clinical And Echocardiographic Findingsgueste220d7c
 
How should recently symptomatic patients be treated urgent cea or cas
How should recently symptomatic patients be treated urgent cea or casHow should recently symptomatic patients be treated urgent cea or cas
How should recently symptomatic patients be treated urgent cea or casuvcd
 
Subarachnoid hemorrhage
Subarachnoid hemorrhage Subarachnoid hemorrhage
Subarachnoid hemorrhage Lobna A.Mohamed
 
cerebral venous sinus thrombosis.pptx
cerebral venous sinus thrombosis.pptxcerebral venous sinus thrombosis.pptx
cerebral venous sinus thrombosis.pptxmohamed elshafei
 
Carpal Tunnel Syndrome- Dr G .Avinash Rao
Carpal Tunnel Syndrome- Dr G .Avinash RaoCarpal Tunnel Syndrome- Dr G .Avinash Rao
Carpal Tunnel Syndrome- Dr G .Avinash RaoUmar Farooq Baba
 

Similar to Acs0602 Asymptomatic Carotid Bruit (20)

Anesthesia for cerebral aneurysm repair
Anesthesia for cerebral aneurysm repairAnesthesia for cerebral aneurysm repair
Anesthesia for cerebral aneurysm repair
 
C.08a-Diagnosis-and-Treatment-of-Acute-Ischemic-Stroke-Presentation-ppt.pptx
C.08a-Diagnosis-and-Treatment-of-Acute-Ischemic-Stroke-Presentation-ppt.pptxC.08a-Diagnosis-and-Treatment-of-Acute-Ischemic-Stroke-Presentation-ppt.pptx
C.08a-Diagnosis-and-Treatment-of-Acute-Ischemic-Stroke-Presentation-ppt.pptx
 
Transient ischemic attacks
Transient ischemic attacksTransient ischemic attacks
Transient ischemic attacks
 
Definition and Evaluation of Transient Ischemic Attack
Definition and Evaluation of Transient Ischemic AttackDefinition and Evaluation of Transient Ischemic Attack
Definition and Evaluation of Transient Ischemic Attack
 
Neurosonology
NeurosonologyNeurosonology
Neurosonology
 
Imaging techniques for myocardial hibernation
Imaging techniques for myocardial hibernationImaging techniques for myocardial hibernation
Imaging techniques for myocardial hibernation
 
CeAD.pptx
CeAD.pptxCeAD.pptx
CeAD.pptx
 
Vertigo
VertigoVertigo
Vertigo
 
Diagnosing Secondary
Diagnosing SecondaryDiagnosing Secondary
Diagnosing Secondary
 
COMPUTATIONAL ASSESSMENT OF INTRA-CRANIAL ANEURYSM
COMPUTATIONAL ASSESSMENT OF INTRA-CRANIAL ANEURYSMCOMPUTATIONAL ASSESSMENT OF INTRA-CRANIAL ANEURYSM
COMPUTATIONAL ASSESSMENT OF INTRA-CRANIAL ANEURYSM
 
Computational Fluid Dynamic Evaluation of Intra-Cranial Aneuryms
Computational Fluid Dynamic Evaluation of Intra-Cranial AneurymsComputational Fluid Dynamic Evaluation of Intra-Cranial Aneuryms
Computational Fluid Dynamic Evaluation of Intra-Cranial Aneuryms
 
2D CFD simulation of intracranial aneurysm
2D CFD simulation of intracranial aneurysm2D CFD simulation of intracranial aneurysm
2D CFD simulation of intracranial aneurysm
 
Transient ischaemic attacks mimics and chameleons
Transient ischaemic attacks mimics and chameleonsTransient ischaemic attacks mimics and chameleons
Transient ischaemic attacks mimics and chameleons
 
Clinical And Echocardiographic Findings
Clinical And Echocardiographic FindingsClinical And Echocardiographic Findings
Clinical And Echocardiographic Findings
 
How should recently symptomatic patients be treated urgent cea or cas
How should recently symptomatic patients be treated urgent cea or casHow should recently symptomatic patients be treated urgent cea or cas
How should recently symptomatic patients be treated urgent cea or cas
 
carpal tunnel syndrome - hand surgery
carpal tunnel syndrome - hand surgerycarpal tunnel syndrome - hand surgery
carpal tunnel syndrome - hand surgery
 
Subarachnoid hemorrhage
Subarachnoid hemorrhage Subarachnoid hemorrhage
Subarachnoid hemorrhage
 
Intracranial bleeding
Intracranial bleedingIntracranial bleeding
Intracranial bleeding
 
cerebral venous sinus thrombosis.pptx
cerebral venous sinus thrombosis.pptxcerebral venous sinus thrombosis.pptx
cerebral venous sinus thrombosis.pptx
 
Carpal Tunnel Syndrome- Dr G .Avinash Rao
Carpal Tunnel Syndrome- Dr G .Avinash RaoCarpal Tunnel Syndrome- Dr G .Avinash Rao
Carpal Tunnel Syndrome- Dr G .Avinash Rao
 

More from medbookonline

Acs0525 splenectomy-2005
Acs0525 splenectomy-2005Acs0525 splenectomy-2005
Acs0525 splenectomy-2005medbookonline
 
Hemigastrectomy, billroth I stapled
Hemigastrectomy, billroth I stapledHemigastrectomy, billroth I stapled
Hemigastrectomy, billroth I stapledmedbookonline
 
Hemigastrectomy, billroth I method
Hemigastrectomy, billroth I methodHemigastrectomy, billroth I method
Hemigastrectomy, billroth I methodmedbookonline
 
Closure of perforation
Closure of perforationClosure of perforation
Closure of perforationmedbookonline
 
A C S0103 Perioperative Considerations For Anesthesia
A C S0103  Perioperative  Considerations For  AnesthesiaA C S0103  Perioperative  Considerations For  Anesthesia
A C S0103 Perioperative Considerations For Anesthesiamedbookonline
 
A C S0105 Postoperative Management Of The Hospitalized Patient
A C S0105  Postoperative  Management Of The  Hospitalized  PatientA C S0105  Postoperative  Management Of The  Hospitalized  Patient
A C S0105 Postoperative Management Of The Hospitalized Patientmedbookonline
 
A C S0106 Postoperative Pain
A C S0106  Postoperative  PainA C S0106  Postoperative  Pain
A C S0106 Postoperative Painmedbookonline
 
A C S0104 Bleeding And Transfusion
A C S0104  Bleeding And  TransfusionA C S0104  Bleeding And  Transfusion
A C S0104 Bleeding And Transfusionmedbookonline
 
A C S0812 Brain Failure And Brain Death
A C S0812  Brain  Failure And  Brain  DeathA C S0812  Brain  Failure And  Brain  Death
A C S0812 Brain Failure And Brain Deathmedbookonline
 
Acs0906 Organ Procurement
Acs0906 Organ ProcurementAcs0906 Organ Procurement
Acs0906 Organ Procurementmedbookonline
 
Acs1001 Normal Laboratory Value
Acs1001 Normal Laboratory ValueAcs1001 Normal Laboratory Value
Acs1001 Normal Laboratory Valuemedbookonline
 

More from medbookonline (20)

Acs0525 splenectomy-2005
Acs0525 splenectomy-2005Acs0525 splenectomy-2005
Acs0525 splenectomy-2005
 
Gastrostomy
GastrostomyGastrostomy
Gastrostomy
 
Hemigastrectomy, billroth I stapled
Hemigastrectomy, billroth I stapledHemigastrectomy, billroth I stapled
Hemigastrectomy, billroth I stapled
 
Hemigastrectomy, billroth I method
Hemigastrectomy, billroth I methodHemigastrectomy, billroth I method
Hemigastrectomy, billroth I method
 
Gastrostomy
GastrostomyGastrostomy
Gastrostomy
 
Gastrojejunostomy
GastrojejunostomyGastrojejunostomy
Gastrojejunostomy
 
Closure of perforation
Closure of perforationClosure of perforation
Closure of perforation
 
A C S0103 Perioperative Considerations For Anesthesia
A C S0103  Perioperative  Considerations For  AnesthesiaA C S0103  Perioperative  Considerations For  Anesthesia
A C S0103 Perioperative Considerations For Anesthesia
 
A C S0105 Postoperative Management Of The Hospitalized Patient
A C S0105  Postoperative  Management Of The  Hospitalized  PatientA C S0105  Postoperative  Management Of The  Hospitalized  Patient
A C S0105 Postoperative Management Of The Hospitalized Patient
 
A C S0106 Postoperative Pain
A C S0106  Postoperative  PainA C S0106  Postoperative  Pain
A C S0106 Postoperative Pain
 
A C S0104 Bleeding And Transfusion
A C S0104  Bleeding And  TransfusionA C S0104  Bleeding And  Transfusion
A C S0104 Bleeding And Transfusion
 
A C S0812 Brain Failure And Brain Death
A C S0812  Brain  Failure And  Brain  DeathA C S0812  Brain  Failure And  Brain  Death
A C S0812 Brain Failure And Brain Death
 
A C S9906
A C S9906A C S9906
A C S9906
 
Acs9903
Acs9903Acs9903
Acs9903
 
Acs9905
Acs9905Acs9905
Acs9905
 
Acs9904
Acs9904Acs9904
Acs9904
 
Acs0906 Organ Procurement
Acs0906 Organ ProcurementAcs0906 Organ Procurement
Acs0906 Organ Procurement
 
Acs9902
Acs9902Acs9902
Acs9902
 
Acs9901
Acs9901Acs9901
Acs9901
 
Acs1001 Normal Laboratory Value
Acs1001 Normal Laboratory ValueAcs1001 Normal Laboratory Value
Acs1001 Normal Laboratory Value
 

Acs0602 Asymptomatic Carotid Bruit

  • 1. © 2004 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice 6 VASCULAR SYSTEM 2 ASYMPTOMATIC CAROTID BRUIT — 1 2 ASYMPTOMATIC CAROTID BRUIT Claudio S. Cinà, M.D., Sp.Chir. (It.), M.Sc., F.R.C.S.(C), Catherine M. Clase, M.B., B.Chir., M.Sc., and Aleksandar Radan, M.D., B.Sc., B.F.A. Assessment of Asymptomatic Carotid Bruit The term bruit refers to any noise detected on auscultation in the hours or causes death.9 Amaurosis fugax is a transient (< 24 hours) neck.The conventional method of auscultation is to use the bell of loss of vision in one eye or a portion of the visual field.9 If a patient the stethoscope and listen over an area extending from the upper with a carotid bruit has a history of any of these conditions in the ip- end of the thyroid cartilage to just below the angle of the jaw.1-3 The silateral eye or brain, then the bruit is regarded as neurologically principal reason why bruits in the neck are matters of some concern symptomatic, and the relevant question at that point is whether the is that they may reflect underlying occlusive carotid artery disease, patient has significant carotid stenosis and may be a candidate for which carries an increased risk of stroke. carotid endarterectomy on that basis. Given the substantial differ- In what follows, we outline a problem-oriented approach to the ences between the management of patients with symptomatic bruits workup of patients found to have cervical bruits at the time of rou- and those with asymptomatic bruits, the distinction between these tine or focused vascular examination. two patient groups is crucial. The history is of critical importance in the diagnosis of TIA be- Clinical Evaluation cause most TIAs last less than 4 hours,10 which means that patients typically are not seen by physicians during the period of neurologic deficit.11 Patients should be specifically asked about transient focal CAROTID BRUITS VERSUS problems with vision, language, facial paresis, dysarthria, and arm OTHER CERVICAL SOUNDS or leg numbness or weakness. A 1984 study reported good interob- Clinical assessment begins server agreement (κ = 0.65) [see Table 1] between clinicians diagnos- with evaluation of the character ing previous ischemic episodes.12 Assigning a probable neurologic of the bruit and examination of territory to a TIA or stroke, however, proved more difficult: for TIAs, the precordium and the cervical the interobserver agreement between two independent neurologists structures. Carotid bruits must be distinguished from other sounds asked to distinguish between carotid and vertebrobasilar events was heard in the neck.Venous hums are relatively common, being report- relatively poor (κ = 0.31).12 There is some evidence that using a stan- ed in 27% of young adults.4 They tend to have a diastolic compo- dardized protocol for the diagnosis of previous ischemic episodes nent, are louder when the patient sits or turns the head away from might improve this low interobserver agreement (e.g., to κ = 0.6512 the side of auscultation, and disappear when the patient lies down or κ = 0.7713). Similar difficulties attend diagnosis of stroke by means or when the Valsalva maneuver is performed.4 Ejection systolic mur- of history and physical examination.14 murs of cardiac origin may radiate into the neck, but generally, they Many patients with a possible TIA or stroke will have undergone are bilateral, are louder within the chest, and are less audible distal- neurologic imaging. Such imaging is unhelpful if it yields negative ly in the neck5; the same is true of bruits arising in other intratho- results; however, in some cases, it reveals the presence of an infarct, racic vessels.6,7 No definitive clinical sign has yet been identified that thereby confirming the ischemic nature of the event and establish- clearly differentiates bruits from transmitted cardiac murmurs. On occasion, a bruit may be heard over the thyroid gland; however, this finding is extremely rare and is usually accompanied by thy- Table 1 Quantification of Interobserver Agreement* romegaly and other features of autoimmune thyroid disease.5 In dialysis patients, a bruit may be generated by the increased flow re- κ† Strength of Agreement sulting from the creation of an arteriovenous fistula in the forearm.8 ≤ 0.2 Poor SYMPTOMATIC VERSUS ASYMP- > 0.2, ≤ 0.4 Fair TOMATIC CAROTID BRUITS > 0.4, ≤ 0.6 Moderate > 0.6, ≤ 0.8 Good Transient ischemic attacks > 0.8, ≤ 1 Very good (TIAs) are defined as brief epi- sodes of focal loss of brain func- *Reliability (how closely an assessment agrees with another similar assessment on a second occasion or by a second observer) and validity (how closely the assessment tion that can usually be localized agrees with another criterion or a gold standard) are the key properties of any assess- ment. When agreement between two observers is poor, the assessment in question, to a specific portion of the brain whether it is a physical finding, a clinical diagnosis, or an interpretation of a diagnostic supplied by a single vascular sys- test, is lacking in reliability; if more reliable methods are available, they should be consid- ered instead. In clinical medicine, however, more reliable methods are not always avail- tem.9 By arbitrary convention, able. When this is the case, the physician must use a relatively unreliable assessment as such an ischemic episode is considered a TIA if it lasts less than 24 the best available alternative, while remaining aware of its limitations.118 † κ is a statistical measure used to quantify agreement between two or more observers. hours; a similar episode, in the absence of evidence of trauma or hem- It takes a value between 0 and 1, where 0 represents agreement no better than that orrhage, is considered an ischemic stroke if it lasts more than 24 expected by chance alone and 1 represents perfect agreement.118
  • 2. © 2004 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice 6 VASCULAR SYSTEM 2 ASYMPTOMATIC CAROTID BRUIT — 2 Noise is detected on auscultation of neck Determine nature of cervical sound. Sound is carotid bruit Distinguish symptomatic bruits from asymptomatic bruits; the decision affects treatment. Bruit is symptomatic Bruit is asymptomatic Perform vascular risk assessment, looking for vascular risk factors (e.g., ↑BP, ↑lipids, diabetes, smoking) and vascular disease (e.g., ischemic cardiac disease, peripheral vascular disease). Initiate modification of vascular risk. Determine subsequent management approach. Assessment of Risk associated with CE is low (Goldman class I or II) Asymptomatic Carotid Bruit Assess risk of carotid stenosis. Risk of carotid stenosis is high Risk of carotid stenosis is low Risk factors include ↑age, ↑BP, smoking, peripheral vascular disease. Assess risk of stroke. Risk of stroke is high Risk of stroke is low Risk factors include age > 70, male sex, ↑BP, ↑lipids, diabetes, smoking, ischemic cardiac disease, peripheral vascular disease. Consult patient preferences regarding surgical treatment. Patient prefers surgical management Patient prefers medical management Determine presence and degree of carotid stenosis with duplex ultrasonography and carotid angiography. Severe stenosis is present Moderate stenosis is present Minimal or no stenosis is present Perform prophylactic CE. Reevaluate with duplex ultrasonography every 1– 2 yr unless patient status changes.
  • 3. © 2004 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice 6 VASCULAR SYSTEM 2 ASYMPTOMATIC CAROTID BRUIT — 3 Sound is venous hum, radiating cardiac murmur or intrathoracic bruit, or thyroid bruit Patient is to be assessed as candidate for Patient is to be managed carotid endarterectomy (CE) conservatively Determine level of risk associated with procedure. Risk associated with CE is high (Goldman class ≥ III) Continue modification of vascular risk. Educate patient regarding symptoms and signs of stroke. Carry out nonsurgical follow-up. Re-refer patient promptly if he or she ever becomes symptomatic.
  • 4. © 2004 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice 6 VASCULAR SYSTEM 2 ASYMPTOMATIC CAROTID BRUIT — 4 ing its location. For a bruit to be regarded as symptomatic on the Table 2 Annual Risk of Stroke basis of imaging studies, at least one infarct must be seen in the ap- propriate ipsilateral anterior vasculature. Patient Population Annual Risk of Stroke It is evident that distinguishing between symptomatic and asymp- tomatic bruits on clinical grounds may be difficult; nonetheless, it Population without bruits, age > 60 yr19,43,44 0.86% (95% CI, 0.8–0.9) Population with bruits, age > 60 yr19,20,43 2.1% (95% CI, 0.6–8.5) is worthwhile to make the effort because the risk of stroke in the Male population without bruits, age > 60 yr19,24 0.9% (95% CI, 0.1–3.0) asymptomatic population is quite different from that in the sympto- Male population with bruits, age > 60 yr19 8.0% (95% CI, 0.2–38.0) matic population. For example, whereas the Asymptomatic Carotid Female population without bruits, age > 60 yr24 2.0% (95% CI, 0.8–4.2) Atherosclerosis Study (ACAS), which included patients believed on Female population with bruits, age > 60 yr19 2.4% (95% CI, 0.7–5.5) clinical grounds to be neurologically asymptomatic, reported an overall stroke rate of 6.2% at 2.7 years in its medically managed group,15 the North American Symptomatic Carotid Endarterecto- gestive heart failure, or peripheral vascular syndrome) will occur in the my Trial (NASCET), which included patients assessed as neurolog- next 5 years is greater than 20%.22,37 In such patients, consultation ically symptomatic (i.e., with a history of amaurosis fugax,TIA, or of formulas or tables is unnecessary, and all modifiable risk factors minor stroke), reported a stroke rate of 26% at 3 years in its med- should be aggressively managed (target BP < 140/90; target ratio of ically managed group.16 total cholesterol to high-density lipoprotein [HDL] cholesterol < 4).22 In determining whether a unilateral bruit is symptomatic or A meta-analysis of randomized, controlled trials showed that as- asymptomatic, the physician should concentrate primarily on is- pirin reduced the risk of subsequent stroke, MI, and death from vas- chemic deficits in the ipsilateral hemisphere (i.e., those causing focal cular events for patients who had previously experienced a cere- contralateral motor or sensory deficits) and ipsilateral amaurosis fu- brovascular event, MI, or unstable angina.38 Other meta-analyses of gax. However, symptoms referable to the contralateral carotid ar- randomized, controlled trials39,40 were unable to confirm the effec- tery, even if no bruit is heard on that side, might prompt evaluation tiveness of aspirin in preventing cerebrovascular events in asympto- of the patient for symptomatic carotid stenosis on the contralateral matic patients or in patients with TIAs or strokes of noncardiac (and side.The absence of a bruit by no means excludes the diagnosis: ca- presumably vascular) origin41; however, one randomized, controlled rotid bruits are absent in 20% to 35% of patients with high-grade trial involving hypertensive patients at modest vascular risk found stenosis of the internal carotid artery.17 In the NASCET subgroup that aspirin reduced the risk of vascular events, if not the risk of in which the physical finding of a carotid bruit was compared with stroke.42 In the absence of contraindications, we recommend that as- angiographic imaging of the carotid system, the presence of a focal pirin be considered for all patients who have established vascular dis- ipsilateral carotid bruit had a sensitivity of 63% and a specificity of ease elsewhere and for all patients who have a bruit in association 61% for high-grade (70% to 99%) stenosis; the absence of a bruit with any vascular risk factors. did not significantly change the probability of significant stenosis in INDICATIONS FOR SURGICAL this population (pretest 52%, posttest 40%).18 INTERVENTION Workup of patients with symptomatic bruits is beyond the scope of this chapter. Accordingly, the ensuing discussion focuses on as- The absolute risk of stroke is sessment of patients with asymptomatic bruits. increased in the presence of a ca- rotid bruit. In population-based VASCULAR RISK ASSESSMENT studies, the annual risk of stroke Vascular diseases and other vascular risk factors are common in was 2.1% (95% confidence in- patients with asymptomatic carotid bruits. Hypertension is twice as terval [CI], 0.6 to 8.5)19,20,43,44 common in patients who have bruits as in those who do not19; for persons who had a carotid smoking, ischemic heart disease, and peripheral vascular disease are bruit and 0.86% (95% CI, 0.8 to 0.9) for those who did not.19,43,44 also more prevalent.20,21 Consequently, detection of a bruit should These figures represent an absolute risk increase for stroke of 1.24% prompt a thorough vascular risk assessment. Standard vascular risk a year and a relative risk for stroke of 2.4. The mean patient age in factors—hypertension, hyperlipidemia, diabetes, and smoking—can these studies was approximately 65 years, and sex distribution and be integrated into risk profiles for particular patients by using either prevalence of risk factors for atherosclerotic disease were similar in the New Zealand risk tables (http://www.nzgg.org.nz/library/gl_ patients with bruits and those without bruits. Even after adjustment complete/bloodpressure/appendix.cfm) or the formula and spread- for age, sex, and the presence of hypertension, the presence of a ca- sheets provided by Anderson et al.22,23 The probability of stroke for rotid bruit remained an independently significant variable, with a various follow-up periods may be quantified by using the Framing- relative risk of 2.0.19 ham stroke-risk profile.24 From age, systolic blood pressure, dia- betes, smoking, cardiovascular disease, atrial fibrillation, and left ven- Table 3 Prevalence of Carotid Stenosis in Patients tricular hypertrophy, probability of stroke may be calculated for men with Bruits and in Healthy Volunteers and women according to a point system.24 Smoking cessation should be recommended to all patients,25-27 Patient Population Prevalence of Carotid Stenosis and hypertension should be controlled (BP < 140/90).28-31 De- pending on a patient’s individual risk profile, dietary and pharma- Overall population with cervical bruits cologic management of hyperlipidemia may also be warranted.32-34 > 35% stenosis20,56-58,119 58% (95% CI, 55–60) Diabetic control should be optimized.35,36 > 60%–75% stenosis56-58 21% (95% CI, 18–24) Patients should be asked specifically about any concurrent vascu- Healthy volunteers* lar disease—in particular, symptoms suggestive of ischemic heart dis- Age > 70 yr89 5.1% (95% CI, 2.6–9.0) ease or of claudication or rest pain. In patients with established vascu- Age ≤ 70 yr89 1.5% (95% CI, 0.2–5.3) lar disease, the risk that future vascular events (e.g., coronary-related *In healthy volunteers, the incidence of asymptomatic carotid stenosis is significantly death, myocardial infarction [MI], new angina, stroke,TIA, new con- correlated with age (P < 0.01) and with the presence of hypertension (P < 0.005).
  • 5. © 2004 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice 6 VASCULAR SYSTEM 2 ASYMPTOMATIC CAROTID BRUIT — 5 nonfatal MI was 2% (95% CI, 1.1 to 3.9), whereas for patients in Table 4 Necessary Criteria for Offering class III or IV, the corresponding figure was 21% (95% CI, 9.2 to an Interventional Approach to Selected 39.9) [see Table 5]. Given that 50 prophylactic carotid endarterec- tomies would have to be performed to prevent one stroke over the Patients with Carotid Bruits subsequent 3-year period (i.e., the number needed to treat [NNT] Center-specific criteria is 50), it is clearly unacceptable to perform this procedure in a pop- Either ulation facing a 21% incidence of MI or death, in which for every 5 DUS is documented to have a > 90% PPV for stenosis > 50% on patients undergoing the operation, one would experience an MI or angiography and is used alone die (i.e., the number needed to harm [NNH] is only 5). Further or consideration of prophylactic carotid endarterectomy in patients for DUS has a lower PPV and is used as a screening test only, and angiography in patients with cerebrovascular disease has a whom the procedure carries a high risk is not warranted. documented complication (stroke or death) rate of around 1% Surgeon-specific criterion High Risk of Carotid Stenosis Perioperative rate of stroke or death is < 3% for carotid Cohort45,54-60 and population- endarterectomy based19,61,62 studies suggest that DUS—duplex ultrasonography PPV—positive predictive value patients with asymptomatic ca- rotid bruits are more likely to have significant carotid stenosis Given the low absolute risk of stroke in asymptomatic patients if they are older, are hyperten- with bruits [see Table 2], the low prevalence of surgically relevant sive, smoke, or have advanced stenosis in patients with bruits [see Table 3], and the small (and peripheral vascular disease. In only marginally statistically significant) absolute benefit of carotid one study, hemodynamically significant stenosis (i.e., > 50%) was endarterectomy in patients with asymptomatic stenosis,45,46 we found by means of ultrasonography in 32% of patients scheduled to and others47-51 do not believe that further investigation with a view undergo peripheral vascular procedures but in only 6.8% of those to carotid endarterectomy is mandatory in the asymptomatic pop- scheduled to undergo coronary artery bypass grafting (CABG).63 ulation. Many surgeons may prefer to manage these patients con- (All figures for degree of stenosis in this chapter are determined ac- servatively, reevaluating them promptly if they become sympto- cording to the formula used in NASCET [see Table 6 and Figure 1].) matic [see Discussion, below]. Other surgeons may wish to pursue Further consideration of carotid endarterectomy may be war- a more interventional strategy with selected patients, in which case ranted in patients with vascular risk factors or known peripheral further evaluation with an eye to surgical treatment depends on vascular disease; in the absence of these findings, the risk of signifi- the presence of the following key findings in a given patient: (1) cant carotid stenosis is low. Further evaluation is unnecessary for low risk associated with carotid endarterectomy, (2) relatively high patients who are younger, do not smoke, are not hypertensive or di- risk of carotid stenosis, and (3) high risk of stroke if carotid steno- abetic, and are not known to have peripheral vascular disease. sis is documented. In addition, the patient’s preferences should be consulted: no patient should be subjected to further evaluation who High Risk of Stroke is not prepared to undergo surgical treatment if such management Within the group of patients is recommended. Patients who, on the basis of any of these crite- with asymptomatic carotid ste- ria, are not suitable candidates for intervention will not benefit nosis, there is only limited direct from imaging studies and should be managed medically. evidence for the existence of sub- Finally, surgeons and centers who are contemplating offering groups of patients at higher risk prophylactic carotid endarterectomy for asymptomatic stenosis for stroke. Men seem to be at should be able to document that their rates of stroke or periopera- higher risk for stroke than wom- tive death for this procedure are lower than 3% [see Table 4].When en are: in the medical arm of complication rates exceed this threshold, the value of carotid endar- ACAS, the incidence of stroke or death at 2.7 years was 7.0% (95% terectomy becomes negligible, and surgeons may find themselves CI, 4.9 to 9.4) for men and 4.9% (95% CI, 2.7 to 8.0) for women. doing more harm than good.45,46 Gender-related differences aside, however, identification of other subgroups at higher risk relies on extrapolation of data from other Low Risk Associated with populations at risk for artery-to-artery embolism. Data from Carotid Endarterectomy NASCET indicate that for symptomatic patients with greater than In NASCET and ACAS, pa- 70% carotid stenosis, the presence of a higher number of identifi- tients were excluded if they had able clinical risk factors (age > 70 years; male sex; systolic or dias- coexisting medical disease likely tolic hypertension; the occurrence of a cerebrovascular event within to produce significant mortality the preceding 31 days; the occurrence of a more serious cerebrovas- and morbidity (e.g., cardiac val- cular event, namely, stroke rather than a TIA or amaurosis fugax; vular or rhythm disorders, un- smoking; MI; congestive heart failure; diabetes; intermittent claudi- controlled hypertension or dia- cation; or hyperlipidemia) was associated with a higher annual betes, unstable angina pectoris, or MI in the previous 4 months)16; stroke risk. For patients with zero to three risk factors, the annual accordingly, the results of these trials are not generalizable to pa- stroke risk was 6.6%; for those with four or five, 9.2%; and for those tients who have such conditions. Further evidence for the impact of with six or more, 15.8%. Data from the same study indicate that operative risk on outcomes is provided by a retrospective review of among patients with a contralateral asymptomatic stenosed carotid 562 patients who underwent carotid endarterectomy for sympto- artery, patients with zero to three risk factors have an annual stroke matic and asymptomatic disease in a large community hospital.52 risk of 1.4% in the territory of the asymptomatic stenosis; those For patients in Goldman class I or II,53 the overall rate of death or with four or five, 2.8%; and those with six or more, 3.8%.64
  • 6. © 2004 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice 6 VASCULAR SYSTEM 2 ASYMPTOMATIC CAROTID BRUIT — 6 Obesity is another risk factor for stroke.49,50 Some 60% of pa- Table 5 Cardiac Risk Assessment* tients who experience a stroke before 65 years of age have a body mass index greater than 24 kg/m2.49 This finding, in conjunction Weighted Score on Cardiac Risk Index with a history of smoking, was found to predict 60% of strokes in Parameter men in this age group.50 Goldman Detsky Eagle Patients with carotid bruits who do not have significant systemic Age > 70 yr 5 5 1 risk factors or other vascular disease are at low absolute risk for stroke and are unlikely to benefit from carotid endarterectomy; MI 1 hence, further investigation is not warranted.5,18,49 Patients with nu- < 6 mo 10 10 merous (i.e., six or more) clinical risk factors [see Table 7] are at rela- > 6 mo 5 tively high risk for stroke, and it is in this population that most of the Angina 1 benefit from carotid endarterectomy is likely to be concentrated. Class III 10 Class IV 20 Patient Preference for Surgical Unstable 10 Intervention Diabetes 1 Before pursuing the diagno- sis of carotid stenosis with im- Operation Emergency 4 10 aging techniques, the surgeon Aortic, abdominal, or thoracic 3 must discuss prophylactic sur- gical intervention with the pa- CHF 11 1 tient. The essential question is, < 1 wk 10 if significant stenosis is docu- > 1 wk 5 mented, will the patient wish to undergo carotid endarterectomy? ECG It should be remembered that at this point in the workup, we are Rhythm other than sinus 7 5 considering only those patients (1) for whom the cardiac risk > 5 PVCs/min 7 5 associated with the procedure is acceptably low and (2) who are Poor medical status† 3 5 considered to be at relatively high risk for stroke if carotid steno- sis is demonstrated. Risk of Perioperative Cardiac Events Patients should be informed that if they are found to have signifi- cant carotid stenosis, their risk of stroke is 6.3% over the ensuing Low 0–12 (class I, II) 0–15 0 2.7 years if they do not undergo operation and 4.0% over the same Intermediate 13–25 (class III) 16–30 1–2 period if they do.15 They should also be informed that these figures High > 25 (class IV) > 30 ≥3 take into account a 3% risk of perioperative stroke or death (2.7% *The Goldman cardiac risk index53 is a multifactorial index of cardiac risk in patients under- risk of stroke and 0.3% risk of death).15 The 2.3% absolute risk re- going noncardiac surgery. Modifications have been proposed by Detsky,121-123 who includ- duction associated with surgical treatment translates into an NNT ed angina and institution-specific perioperative cardiac event rates in the model. The Eagle index124-126 is another risk index based on five clinical variables. Despite the lack of con- of 43, meaning that 43 patients would have to undergo endarterec- sensus regarding the relative merits of these tools for preoperative cardiac risk assessment, stratification of patients into risk categories is helpful in assessing the risk and benefits of a tomy to prevent one stroke over the next 2.7 years. procedure such as carotid endarterectomy. Given the front-loaded risks of surgery, some patients will prefer † PaO2 < 60 mm Hg; PaCO2 > 50 mm Hg; K+ < 3 mmol/L; serum HCO3 < 20 mmol/L; serum urea > 18 mmol/L; creatinine > 260 µmol/L; abnormal ALT; signs of chronic liver disease; a simple risk-modification strategy to a strategy including both risk bedridden from cardiac causes. modification and surgical intervention. In such cases, carotid imag- CHF—congestive heart failure MI—myocardial infarction PVC—premature ventricular contraction ing is not necessary, because knowledge of the degree of stenosis will not affect subsequent management. than 50% stenosis (determined by means of angiography, the gold standard), DUS had a sensitivity of 91% (95% CI, 89 to 94) and a Investigative Studies specificity of 93% (95% CI, 88 to 95).67 Given a disease prevalence The purpose of investigation of approximately 41% in patients referred for DUS, these findings of asymptomatic neck bruits is to translate into a positive predictive value of 90% and an accuracy of identify persons with significant 92%.67 A subsequent prospective study of patients (both sympto- carotid stenosis who are at in- matic and asymptomatic) in whom carotid endarterectomy was being creased risk for cerebrovascular considered reported a sensitivity of 100% and a specificity of 98% for disease65,66 and who are likely to greater than 60% stenosis, with a positive predictive value of 99%.68 benefit from carotid endarterec- At centers where DUS has been internally validated in com- tomy. In the absence of other sig- parison with angiography and where this level of performance nificant findings, cervical bruits are not sufficiently predictive of sig- has been documented, the surgeons may choose to proceed to nificant carotid stenosis or ischemic stroke to be useful in selecting surgery without angiography.68-70 At centers where DUS is less candidates for noninvasive imaging.51 Noninvasive testing is a rea- reliable, however, it should be regarded as a screening test, and sonable step in patients with the characteristics listed above, but angiography should be performed when DUS suggests greater routine screening of all patients with asymptomatic carotid bruits is than 50% stenosis. not warranted.51 CAROTID ANGIOGRAPHY DUPLEX ULTRASONOGRAPHY As an invasive procedure, carotid angiography carries a significant Duplex ultrasonography (DUS) should be performed bilaterally.A risk of morbidity and mortality. All centers performing carotid an- meta-analysis conducted in 1995 found that for detecting greater giography for cerebrovascular disease should audit their stroke rates
  • 7. © 2004 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice 6 VASCULAR SYSTEM 2 ASYMPTOMATIC CAROTID BRUIT — 7 Table 6 Conversion between Different Methods of Measuring Degree of Carotid Stenosis Severity of Disease Method Minimal Moderate Severe Occlusion ECST* 24%–57% 58%–69% 70%–81% 82%–99% 100% NASCET 0%–29% 30%–49% 50%–69% 70%–99% 100% † CC method 35%–56% 57%–61% 62%–80% 81%–99% 100% *Conversion from ECST to NASCET was done according to the following formula: ECST % stenosis = 0.6(NASCET % stenosis) + 40.127 † The relation of the NASCET method to the CC method is linear, with a ratio of 0.62 between the distal internal carotid diameter and the common carotid diameter.117 periodically. Since 1990, four prospective studies71-74 have addressed greater degrees of stenosis would be associated with greater risk of the question of the risks associated with angiography in patients with stroke.This finding may be explained either by the fact that duplex atherosclerotic cerebrovascular disease. When the data from these ultrasound was the sole imaging criterion or that plaque morpholo- studies were pooled, the risk of permanent neurologic deficit or death gy plays a greater role in determining stroke risk than degree of ste- was 1.1% (95% CI, 0.6 to 2.0).75 In ACAS, the 1.2% of patients in nosis. Furthermore, unlike previous studies, many of the patients in the intervention arm who experienced stroke or died after angiogra- the ACST were receiving lipid-lowering drugs and other antiplatelet phy accounted for 40% of the strokes and deaths attributable to sur- agents. As Barnett pointed out in his discussion of the ACST article, gical intervention.15 Angiographic complication rates significantly the perioperative stroke rate must be low for the results of this study worse than these will adversely impact the risk-benefit ratio associat- to be generalized.81 In the ACST, the risk of stroke or death within ed with surgical intervention. Centers that consistently record rela- 30 days of undergoing carotid endarterectomy was 3.1%. tively high angiographic complication rates should not offer evalua- Technical details of carotid endarterectomy are discussed else- tion for and surgical treatment of asymptomatic carotid disease. where [see 6:9 Surgical Treatment of Carotid Artery Disease]. PATIENT EDUCATION Management All patients with asymptomatic carotid bruits, whether they are CAROTID ENDARTERECTOMY undergoing prophylactic endarterectomy or not, should be carefully At this point in management, it is reasonable to offer surgical treat- advised regarding the symptoms and signs of stroke, TIAs, and ment of asymptomatic disease to patients with greater than 50% ste- amaurosis fugax and should be strongly encouraged to seek urgent nosis. ACAS15 and two meta-analyses45,46 that included other trials of medical attention if such problems arise. Patients who experience surgical therapy for asymptomatic carotid stenosis documented a one of these untoward events should undergo full reevaluation for small and marginally statistically significant benefit from prophylactic stroke risk factors (e.g., hypertension, hyperlipidemia, diabetes, smok- carotid endarterectomy in asymptomatic patients with greater than ing, and atrial fibrillation); in the absence of atrial fibrillation (which 50% to 60% carotid stenosis. Because the absolute benefit is small, we do not consider it obligatory to pursue the diagnosis or to follow Internal an invasive strategy in patients identified solely on the basis of an Carotid Artery asymptomatic bruit; however, patients possessing all the characteris- External Carotid Artery tics listed earlier [see Indications for Surgical Intervention, above] probably constitute a group that is particularly able to benefit from B surgical intervention. Patients with higher degrees of stenosis are at higher risk for stroke and are therefore most likely to benefit.76-79 The degree of stenosis and the presence or absence of plaque ul- ECST Method ceration may modify the final decision for or against operative man- C–A x 100% Stenosis agement [see Discussion, Subgroup Analyses for Potential High- C A Risk Factors, below]. In May 2004, the United Kingdom Medical Research Council C NASCET Method Asymptomatic Carotid Surgery Trial (ACST) collaborative group B–A x 100% Stenosis reported the results of a prospective, randomized trial of carotid B endarterectomy in asymptomatic patients.80 More than 3,000 pa- tients were randomly assigned either to undergo immediate carotid D CC Method endarterectomy or to be placed on indefinite deferral. In the patients D–A referred for immediate carotid endarterectomy, one half underwent D x 100% Stenosis endarterectomy within 1 month of referral; 88% underwent endar- terectomy within 1 year. Combining the rate of perioperative events Common Carotid Artery and nonperioperative strokes, the 5-year results indicate a stroke rate of 6.4% in the group undergoing immediate carotid endarterecto- Figure 1 Carotid angiography remains the gold standard for de- my, as compared with 11.8% in the deferral group.These findings termining the extent of carotid arterial disease. Several methods are strikingly similar to the ACAS findings. However, the ACST of reporting angiographically defined stenosis have been described found a similar benefit for women. In addition, in the ACST, no dif- in the literature.115 The most commonly used methods are those ference was found in the degree of stenosis and the benefit of adopted by the NASCET and ECST investigators, though the so- surgery—an interesting observation, because one would expect that called common carotid (CC) method has its advocates as well.116,117
  • 8. © 2004 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice 6 VASCULAR SYSTEM 2 ASYMPTOMATIC CAROTID BRUIT — 8 ter a stroke.75 Performing endarterectomy early reduces the risk pe- Table 7 Risk Factors for Stroke128,129 riod for recurrent stroke and may therefore increase the potential benefit of the intervention; the usual approach is to perform the Age > 70 yr Smoking (or history of smoking) procedure within a week or two of a patient’s first neurologic event. Male sex > 80% carotid stenosis Management of cardiovascular risk factors and concurrent vascu- Hypertension* Presence of ulceration lar disease should continue. In the absence of concurrent vascular Hyperlipidemia Ischemic heart disease† disease, patients may be referred back to the family practitioner, in- Diabetes Peripheral vascular disease ternist, or cardiologist in place of specific surgical follow-up. *Defined as systolic BP > 160 mm Hg or diastolic BP > 90 mm Hg. † MI or CHF. FOLLOW-UP OF PATIENTS WITH LOWER-GRADE STENOSIS Carotid stenosis progresses in about one quarter of patients with asymptomatic carotid stenosis monitored with DUS over a 2-year should prompt consideration of prophylactic anticoagulation82-84), a period.87 In a population of asymptomatic patients with bruits who change in antiplatelet therapy should be considered. Both ticlopi- were referred to a vascular laboratory, 282 stenotic carotid arteries dine85 and clopidogrel86 are more effective than aspirin in preventing (average stenosis, 50%) were followed for 38 ± 18 months. Progres- stroke. (Ticlopidine is associated with reversible but severe neutro- sion of stenosis, defined as an increase in degree of stenosis to 80% penia in fewer than 1% of cases; accordingly, monitoring for this or beyond, occurred in 17% of arteries, and 2% became complete- complication is indicated.) ly occluded. Progression was associated with an increase in stroke If a patient who is a surgical candidate experiences a TIA or risk of 4.9% at 1 year, 16.7% at 3 years, and 26.5% at 5 years. In stroke as a result of an ischemic event in the carotid region in the comparison, the estimated stroke risk in an asymptomatic popula- absence of atrial fibrillation, he or she must be promptly referred tion of patients with 50% to 79% stenosis was 0.85%, 3.6%, and back to the vascular surgeon.This possibility should be clearly ex- 5.4% for the same three periods (P = 0.001).76 plained to patients once the initial evaluation is complete and they Although carotid stenosis, once identified, tends to progress over have been referred back to their primary care physicians. Patients time,20,54,76,88 the data are currently insufficient to permit recommenda- referred back to a vascular surgeon under these circumstances tion of routine ultrasonographic or other surveillance for all patients should then be regarded as having symptomatic carotid disease. A with neck bruits outside a research setting. In our view, reevaluation subgroup analysis of patients with symptomatic stenosis reported every 1 to 2 years with noninvasive diagnostic tests is a reasonable ap- that carotid endarterectomy performed soon after a nondisabling proach to patients (1) who are already known to have greater than 50% stroke was not associated with a significantly higher operative com- stenosis, (2) who do not undergo surgery, and (3) who are at high risk plication rate than endarterectomy performed 30 days or longer af- for stroke, are surgical candidates, and are not averse to surgery. Discussion Epidemiology Economic Considerations In cross-sectional and population-based studies, the overall prev- A cogent argument in favor of pursuing a surgical strategy in at alence of greater than 75% carotid stenosis has been low. A 1992 least some patients was made by a 1997 economic analysis,90 which study reported a 2.3% prevalence in men and a 1.1% prevalence in demonstrated that although prophylactic endarterectomy in patients women; there was a significant (P < 0.0001) increase with age with with asymptomatic carotid stenosis did not reduce societal costs ap- each decade from 65 years to beyond 85 years, but there were no preciably, it was nonetheless, at a cost of $8,000/quality-adjusted life significant differences between men and women.62 In the Framing- year (QALY), within the range of many interventions considered by ham study population, the incidence of greater than 50% stenosis society to be cost-effective. It should be pointed out, however, that was 8% (95% CI, 6.5 to 9.8).61 In a study of healthy volunteers, the this economic analysis addressed only carotid endarterectomy in pa- incidence of greater than 50% stenosis was 5.1% (95% CI, 2.6 to tients with identified carotid stenosis, not screening strategies for pa- 9.0) in patients 70 years of age or older and 1.5% (95% CI, 0.2 to tients with bruits, and consequently did not consider costs associat- 5.3) in younger patients.89 ed with investigation and follow-up to the point of recommendation The pooled risk of greater than 60% to 75% stenosis in patients for or against carotid endarterectomy in the broader group of pa- with carotid bruits referred for noninvasive vascular evaluation at an tients with bruits.These costs would alter the economic analysis sub- average age of 65 years is reported to be 21% (95% CI, 18 to 24),56-58 stantially, and if they are included, it is far from clear whether the re- which is three to four times the prevalence expected on the basis of sulting overall cost/QALY would still be acceptable.To date, no trial population-based studies.Thus, five persons with neck bruits must or economic analysis of a screening strategy has been published. be screened to detect one patient with moderate to severe carotid stenosis.The absolute benefit of surgery is small and of borderline Screening Issues statistical significance. In ACAS, as noted (see above), the relative risk reduction for an ipsilateral major stroke or perioperative death For the reasons previously discussed, we do not feel justified in over a 2.7-year period was 36.5% (95% CI, 27.5 to 47.1), the abso- recommending routine screening for patients with asymptomatic lute risk reduction was 2.3% (95% CI, 0.2 to 7.0), and the NNT carotid bruits. Given the available evidence, we believe that such pa- was 43 (95% CI, 14 to 500); the number of patients that would have tients may reasonably be managed in either of two ways. One to be screened with DUS to prevent one stroke over a 3-year follow- choice is simply to conclude that screening patients with carotid up period was 250 (95% CI, 70 to 2,500). bruits as possible candidates for carotid endarterectomy has not
  • 9. © 2004 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice 6 VASCULAR SYSTEM 2 ASYMPTOMATIC CAROTID BRUIT — 9 PLAQUE ULCERATION AND PLAQUE STRUCTURE been proved to be a useful intervention and to concentrate instead on general vascular risk reduction.The other, which is appropriate At present, there are no subgroup analyses examining the effect in centers where noninvasive or invasive diagnostic tests reach ac- of plaque ulceration on the ability of asymptomatic patients to ben- ceptable standards with an acceptable degree of risk and where the efit from surgical treatment. In NASCET, however, when sympto- procedure is done by surgeons whose documented perioperative matic patients with 70% to 99% stenosis were considered, those stroke and death rates are less than 3%, is to take a selective ap- with angiographic evidence of plaque ulceration were at higher risk proach that addresses various issues related to stroke risk, cardiac for stroke than those without ulceration92 and derived greater bene- risk, and patient preferences before noninvasive tests are ordered. fit from surgery.75 Angiography had a sensitivity of 46% and a speci- ficity of 74% in the detection of ulcerated plaques, with a positive predictive value of 72%.93 A 1994 study reported that when ulcera- Subgroup Analyses for Potential High-Risk Factors tion was detected with B-mode imaging in patients with asympto- Given the small absolute risk reduction reported by ACAS15 matic carotid stenosis, the incidence of silent cerebral infarction de- and by the two meta-analyses of all asymptomatic carotid stenosis tected by magnetic resonance imaging was 75%, compared with an trials,45,46 it would be useful to be able to identify one or more incidence of 25% when ulceration was absent.94 high-risk groups within the broader group of patients identified as It has also been suggested that carotid plaques of differing struc- having stenosis. tures may have differing embolic potentials.95 DUS can distinguish between fibrous plaques (which are highly echogenic) and plaques SEX with high concentrations of lipid and necrotic material (which are ACAS included a subgroup analysis addressing the effect of sex echolucent). Echolucent plaques are more frequently associated on ability to benefit from surgery: the absolute reduction in the risk with neurologic symptoms and computed tomography–proven ce- of perioperative stroke or death or ipsilateral stroke at 2.7 years was rebral infarction.95-97 Interobserver reliability for plaque echostruc- 3.6% (95% CI, 1.1 to 9.9) for men and 0.5% (95% CI, 0.01 to 2.7) ture, however, seems to be highly variable, ranging from good (κ = for women. 0.79) for greater than 70% stenosis95 to average (κ = 0.51) for greater than 40% stenosis98 to poor (κ = 0.29) for greater than 80% DEGREE OF STENOSIS stenosis.99 A 1994 report found no correlation between the pres- In asymptomatic patients stratified according to their ultrasono- ence or type of symptoms and plaque structure as determined by graphically determined degree of stenosis, the risk of stroke is low DUS.100 The true importance of carotid plaque echomorphology both for patients with less than 30% stenosis (4% cumulative event and surface characteristics as predictors of cerebrovascular events rate at 3 years) and for those with 30% to 74% stenosis (9% cumu- remains to be defined. lative event rate at 3 years); it is highest for those with greater than CONTRALATERAL DISEASE 75% stenosis (21% cumulative event rate at 3 years).20 The Euro- pean Carotid Surgery Trialists (ECST) study,47 using angiographic It has been suggested that the presence of contralateral carotid dis- data from the asymptomatic carotid arteries of 2,295 patients, re- ease is a risk factor for future cerebrovascular events. In NASCET pa- ported that the Kaplan-Meyer estimate of stroke risk at 3 years was tients with greater than 70% stenosis,101 contralateral occlusion signif- only 2% and remained low (< 2%) when patients with less than icantly increased the benefit of surgery with respect to the incidence 79% stenosis were considered; stroke risk increased to 9.8% for pa- of stroke or death, but contralateral high-grade stenosis did not.75 tients with 70% to 79% stenosis and to 14.4% for those with 80% ASYMPTOMATIC CEREBRAL INFARCTION to 99% stenosis. In a population of patients referred to a vascular laboratory with asymptomatic carotid stenosis on DUS who were The presence of areas of asymptomatic cerebral infarction ipsilat- followed for a mean of 38 months, the incidence of stroke was 2.1% eral to the area of carotid stenosis on head CT may identify patients in patients with 50% to 79% stenosis and 10.4% in those with great- who would benefit from surgery.102 In asymptomatic patients with er than 80% stenosis.76 carotid stenosis, the incidence of silent strokes demonstrated by CT In ACAS, there were too few strokes to permit subgroup analysis has been reported to be 10% in patients with 35% to 50% stenosis of the effect of degree of stenosis on ability to benefit from carotid on DUS, 17% in those with 50% to 75% stenosis, and 30% in endarterectomy. In both ECST79 and NASCET,75,77,78,91 however, those with greater than 75% stenosis.103 The incidence of silent higher degrees of stenosis in symptomatic patients were consistent- cerebral infarctions demonstrated by MRI in the same type of pop- ly observed to be associated with higher stroke risk as well as with ulation has been reported to be 42%, increasing to 75% for greater greater ability to benefit from surgical treatment [see Table 8]. than 50% stenosis.94 Use of CT and MRI of the brain in risk strati- Table 8 Effectiveness of Surgery by Degree of Stenosis in Patients with Symptomatic Carotid Stenosis75 Degree Relative Risk Reduction Absolute Risk Reduction Number Needed to Treat of Stenosis or Increase or Increase or Harm 70%–99% RRR, 48% (95% CI, 27–63) ARR, 6.7% (95% CI, 3.2–10) NNT, 15 (95% CI, 10–31) 50%–69% RRR, 27% (95% CI, 5–44) ARR, 4.7% (95% CI, 0.8–8.7) NNT, 21 (95% CI, 11–125) ≤ 49% RRI, 20% (95% CI, 0–44) ARI, 2.2% (95% CI, 0–4.4) NNH, 45 (95% CI, 22–∝) ARI—absolute risk increase ARR—absolute risk reduction NNH—number needed to harm NNT—number needed to treat RRI—relative risk increase RRR—relative risk reduction
  • 10. © 2004 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice 6 VASCULAR SYSTEM 2 ASYMPTOMATIC CAROTID BRUIT — 10 fication of patients with asymptomatic carotid stenosis is controver- CI, 2.1 to 4.5), the MI rate is 5.2% (95% CI, 3.6 to 6.9)—a non- sial and currently is not advised. significant increase—and the mortality is 4.7% (95% CI, 3.4 to 6.4).109 For cohorts in which CABG was done first and carotid ste- CONCLUSIONS nosis was treated on its own after the cardiac procedure, the stroke Although only limited data on patients with asymptomatic steno- rate is 3.5% (95% CI, 1.0 to 9.0), the MI rate is 2% (95% CI, 0.2 to sis are available, we believe that consideration of sex, degree of steno- 6.0), and the mortality is 0.8% (95% CI, 0.02 to 4.8).110-112 sis, and possibly the presence of plaque ulceration may be helpful in We recommend against a combined surgical approach in patients making the final decision on whether to offer carotid endarterecto- with asymptomatic carotid stenosis. Given the equivalent stroke rate my to these patients; at present, plaque morphology is insufficiently and the lower MI rate and mortality, we believe that the preferred reliable to be a useful guide to clinical management. strategy in patients with bruits is first to proceed with CABG if indi- cated and then to determine whether the patient should be further Special Situations evaluated as a candidate for carotid endarterectomy in the same manner as other elective patients would be. RESTENOSIS OR PREVIOUS CAROTID SURGERY Patients who have previously undergone carotid surgery have Effect of Center-Specific Variations on Risk-to-Benefit Ratio been excluded from most studies of asymptomatic patients; when they have been included in trials addressing symptomatic stenosis, In ACAS, 1.2% of the overall 2.7% perioperative stroke rate was they have experienced increased rates of perioperative complica- accounted for by strokes occurring after angiography. Centers where tions.16,50 Patients in whom restenosis occurs after an earlier carot- ultrasonography has been documented to have high predictive val- id endarterectomy should be advised against surgery while they ues may avoid this risk by proceeding directly from ultrasonography remain asymptomatic.15 It is therefore unnecessary to follow pa- to surgery. If these complications had been avoided in ACAS, the tients with ultrasonography after carotid endarterectomy if no absolute risk reduction would have been more substantial: 3.43% symptoms develop. (95% CI, 1.1 to 9.9), corresponding to an NNT of 29 (95% CI, 1 to 80). The true perioperative combined stroke and death rate PREOPERATIVE ASSESSMENT FOR CORONARY ARTERY BYPASS achieved in this study was 1.5%, a result that is definitive of excel- GRAFTING lence in the surgical management of carotid endarterectomy and Some 20% to 30% of patients undergoing assessment for CABG that constitutes a useful quality assurance measure for centers and are found to have carotid bruits,49,104 and 5% to 20% have greater individual surgeons. than 50% stenosis on DUS105-107 or ocular plethysmography.108 In asymptomatic patients with carotid stenosis who are undergoing Issues for the Future CABG, there is no direct evidence favoring prophylactic carotid endarterectomy either before or in conjunction with CABG. Co- It is possible, perhaps likely, that in the future, magnetic reso- hort studies including symptomatic and asymptomatic carotid ste- nance angiography67 and three-dimensional CT angiography,113,114 nosis indicate that patients undergoing CABG and carotid endarter- together with DUS, will replace angiography as preferred imaging ectomy in the same operation have a stroke rate of 6% (95% CI, 4.6 methods for diagnosing internal carotid artery stenosis. As for surgi- to 7.8), an MI rate of 4.6% (95% CI, 3.1 to 6.5), and a mortality of cal treatment and screening, further data on patients with asympto- 4.7% (95% CI, 3.4 to 6.4).109 For cohorts in which carotid endarter- matic carotid stenosis are necessary before definitive recommenda- ectomy was performed before CABG, the stroke rate is 3.2% (95% tions can be made. References 1. Chambers BR, Norris JW: Clinical significance of Cerebrovascular Diseases III. Stroke 21:637, 1990 tomy Trial Collaborators (NASCET): Beneficial ef- asymptomatic neck bruits. Neurology 35:742, 1985 10. Werdelin L, Juhler M:The course of transient ische- fect of carotid endarterectomy in symptomatic pa- 2. Harrison MJ: Cervical bruits and asymptomatic ca- mic attacks. Neurology 38:677, 1988 tients with high-grade carotid stenosis. N Engl J Med rotid stenosis. Br J Hosp Med 32:80, 1984 325:445, 1991 11. Albers GW, Hart RG, Lutsep HL, et al: AHA Scien- 3. Ratcheson RA: Clinical diagnosis of atherosclerotic 17. Davies KN, Humphrey PRD: Do carotid bruits pre- tific Statement. Supplement to the guidelines for the carotid artery disease. Clin Neurosurg 29:464, 1982 dict disease of the internal carotid arteries? Postgrad management of transient ischemic attacks: a state- Med J 70:433, 1994 4. Jones FL: Frequency, characteristics and importance ment from the Ad Hoc Committee on Guidelines for the Management of Transient Ischemic Attacks, 18. Sauve JS,Thorpe KE, Sackett DL, et al: Can bruits of the cervical venous hum in adults. N Engl J Med Stroke Council, American Heart Association. Stroke distinguish high-grade from moderate symptomatic 267:658, 1962 30:2502, 1999 carotid stenosis? The North American Symptomatic 5. Sauve JS, Laupacis A, Ostbye T, et al: Does this pa- Carotid Endarterectomy Trial. Ann Intern Med 120: tient have a clinically important carotid bruit? JAMA 12. Kraaijeveld CL, van Gijn J, Schouten HJ, et al: Inter- 633, 1994 270:2843, 1993 observer agreement for the diagnosis of transient is- chemic attacks. Stroke 15:723, 1984 19. Heyman A, Wilkinson WE, Heyden S, et al: Risk of 6. Caplan LR: Carotid artery disease. N Engl J Med stroke in asymptomatic persons with cervical arterial 315:886, 1986 13. Koudstaal PJ, van Gijn J, Staal A, et al: Diagnosis of bruits: a population study in Evans County, Georgia. transient ischemic attacks: improvement of inter- N Engl J Med 302:838, 1980 7. Thompson JE, Patman RD,Talkington CM: Asymp- observer agreement by a check-list in ordinary lan- tomatic carotid bruit: long term outcome of patients 20. Chambers BR, Norris JW: Outcome in patients with having endarterectomy compared with unoperated guage. Stroke 17:723, 1986 asymptomatic neck bruits. N Engl J Med 315:860, controls. Ann Surg 188:308, 1978 14. von Arbin M, Britton M, de Faire U, et al:Validation 1986 8. Messert B, Marra TR, Zerofsky RA: Supraclavicular of admission criteria to a stroke unit. J Chronic Dis 21. Meissner I,Wiebers DO,Whisnant JP, et al:The nat- and carotid bruits in hemodialysis patients. Ann Neu- 33:215, 1980 ural history of asymptomatic carotid artery occlusive rol 2:535, 1977 15. Toole JF, Baker WH, Castaldo JE, et al: Endarterecto- lesions. JAMA 258:2704, 1987 9. National Institute of Neurological Disorders and my for asymptomatic carotid artery stenosis. JAMA 22. Anderson KM, Odell PM,Wilson PW, et al: Cardio- Stroke: Special Report from the National Institute of 273:1421, 1995 vascular disease risk profiles. Am Heart J 121(1 pt 2): Neurological Disorders and Stroke. Classification of 16. North American Symptomatic Carotid Endarterec- 293, 1991
  • 11. © 2004 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice 6 VASCULAR SYSTEM 2 ASYMPTOMATIC CAROTID BRUIT — 11 23. Anderson KM,Wilson PW, Odell PM, et al: An up- domised trial. HOT Study Group. Lancet 351:1755, rotic disease of the aortic arch and the risk of is- dated coronary risk profile: a statement for health 1988 chemic stroke. N Engl J Med 331:1474, 1994 professionals. Circulation 83:356, 1991 43. Wiebers DO, Whisnant JP, Sandok BA, et al: Pro- 67. Blakeley DD, Oddone EZ, Hasselblad V, et al: Non- 24. Wolf PA, D’Agostino RB, Belanger AJ, et al: Proba- spective comparison of a cohort with asymptomatic invasive carotid artery testing: a meta-analytic review. bility of stroke: a risk profile from the Framingham carotid bruit and a population-based cohort without Ann Intern Med 122:360, 1997 Study. Stroke 22:312, 1991 carotid bruit. Stroke 21:984, 1990 68. Ballotta E, DaGiau G, Abbruzzese E, et al: Carotid 25. Wolf PA, D’Agostino RB, Kannel WB, et al: Cigarette 44. Shorr RI, Johnson KC,Wan JY, et al:The prognostic endarterectomy without angiography: can clinical smoking as a risk factor for stroke.The Framingham significance of asymptomatic carotid bruits in the el- evaluation and duplex ultrasonographic scanning Study. JAMA 259:1025, 1988 derly. J Gen Intern Med 13:86, 1998 alone replace traditional arteriography for carotid 26. Wannamethee SG, Shaper AG, Whincup PH, et al: 45. Benavente OR, Moher D, Pham B: Carotid endarter- surgery workup? A prospective study. Surgery 126: Smoking cessation and the risk of stroke in middle- ectomy for asymptomatic carotid stenosis: a meta- 20, 1999 aged men. JAMA 274:155, 1995 analysis. BMJ 317:1477, 1998 69. Wolf RK, Williams EL II, Kistler PC: Transbrachial 27. Shinton R, Beevers G: Meta-analysis of relation be- 46. Chambers BR,You RX, Donnan GA: Carotid endar- balloon catheter tamponade of ruptured abdominal tween cigarette smoking and stroke. BMJ 298:789, terectomy for asymptomatic carotid stenosis. Coch- aortic aneurysms without fluoroscopic control. Surg 1989 rane Database Syst Rev (2):CD001923, 2000 Gynecol Obstet 164:463, 1987 28. Prevention of stroke by antihypertensive drug treat- 47. European Carotid Surgery Trialists’ Collaborative 70. Baird RN: Should carotid endarterectomy be pur- ment in older persons with isolated systolic hyperten- Group: Risk of stroke in the distribution of an asymp- chased? treatment avoids much morbidity. BMJ 310: sion: final results of the Systolic Hypertension in the tomatic carotid artery. Lancet 345:209, 1995 316, 1995 Elderly Program (SHEP). SHEP Cooperative Re- 71. Hankey GJ, Warlow CP, Molyneux AJ: Complica- 48. Gorelick PB: Carotid endarterectomy: where do we search Group. JAMA 265:3255, 1991 tions of cerebral angiography for patients with mild draw the line? (editorial) Stroke 30:1745, 1999 29. Sutton-Tyrrell K, Alcorn HG, Herzog H, et al: Mor- carotid territory ischaemia being considered for ca- 49. Gorelick PB, Sacco RL, Smith DB, et al: Prevention rotid endarterectomy. J Neurol Neurosurg Psychiatry bidity, mortality, and antihypertensive treatment ef- of a first stroke: a review of guidelines and a multidis- 53:542, 1990 fects by extent of atherosclerosis in older adults with ciplinary consensus statement from the National isolated systolic hypertension. Stroke 26:1319, 1995 72. Heiserman JE, Dean BL, Hodak JA, et al: Neurolog- Stroke Association. JAMA 281:1112, 1999 30. Sutton-Tyrrell K, Wolfson SK Jr, Kuller LH: Blood ic complications of cerebral angiography. AJNR Am J 50. Feinberg RW: Primary and secondary stroke preven- Neuroradiol 15:1401, 1994 pressure treatment slows the progression of carotid tion. Curr Opin Neurol 9:46, 1996 stenosis in patients with isolated systolic hyperten- 73. Davies KN, Humphrey PR: Complications of cere- sion. Stroke 25:44, 1994 51. Lee TT, Solomon NA, Heidenreich PA, et al: Cost- bral angiography in patients with symptomatic carot- effectiveness of screening for carotid stenosis in asymp- id territory ischaemia screened by carotid ultrasound. 31. Collins R, Peto R, MacMahon S, et al: Blood pres- tomatic persons. Ann Intern Med 126:337, 1997 sure, stroke, and coronary heart disease. Part 2, Short- J Neurol Neurosurg Psychiatry 56:967, 1993 term reductions in blood pressure: overview of ran- 52. Musser DJ, Nicholas GG, Reed JF III: Death and 74. Grzyska J, Freitag J, Zeumer H: Selective cerebral in- domised drug trials in their epidemiological context. adverse cardiac events after carotid endarterectomy. traarterial DSA: Complication rate and control of Lancet 335:827, 1990 J Vasc Surg 19:615, 1994 risk factors. Neuroradiology 32:296, 1990 32. Randomised trial of cholesterol lowering in 4444 pa- 53. Goldman L, Caldera DL, Nussbaum SR, et al: Mul- 75. Cinà CS, Clase CM, Haynes RB: Refining indi- tients with coronary heart disease: the Scandinavian tifactorial index of cardiac risk in noncardiac surgical cations for carotid endarterectomy in patients with Simvastatin Survival Study (4S). Lancet 344:1383, procedures. N Engl J Med 297:845, 1977 symptomatic carotid stenosis: a systematic review. 1994 54. Roederer GO, LangloisYE, Jager KA, et al:The natu- J Vasc Surg 30:606, 1999 33. Furberg CD: Lipid-lowering trials: results and limita- ral history of carotid arterial disease in asymptomatic 76. Rockman CB, Riles TS, Lamparello PJ, et al: Natural tions. Am Heart J 128(6 pt 2):1304, 1994 patients with cervical bruits. Stroke 15:605, 1984 history and management of the asymptomatic, mod- 34. Furberg CD, Adams HP Jr, Applegate WB, et al: Ef- 55. Fowl RJ, Marsh JG, Love M, et al: Prevalence of he- erately stenotic internal carotid artery. J Vasc Surg fect of lovastatin on early carotid atherosclerosis and modynamically significant stenosis of the carotid ar- 25:423, 1997 cardiovascular events. Asymptomatic Carotid Artery tery in an asymptomatic veteran population. Surg 77. Cina CS, Clase CM, Haynes RB: Carotid endarte- Progression Study (ACAPS) Research Group. Circu- Gynecol Obstet 172:13, 1991 rectomy for symptomatic carotid stenosis. Cochrane lation 90:1679, 1994 56. Zhu CZ, Norris JW: Role of carotid stenosis in is- Database Syst Rev (2):CD001081, 2000 35. The effect of intensive treatment of diabetes on the chemic stroke. Stroke 21:1131, 1990 78. Rothwell PM, Slattery J,Warlow CP: Clinical and an- development and progression of long-term complica- 57. AbuRahma AF, Robinson PA: Prospective clinico- giographic predictors of stroke and death from carotid tions in insulin-dependent diabetes mellitus.The Di- pathophysiologic follow-up study of asymptomatic endarterectomy: systematic review. BMJ 315:1571, abetes Control and Complications Trial Research neck bruit. Am Surg 56:108, 1990 1997 Group. N Engl J Med 329:977, 1993 58. Lusiani L,Visonà A, Castellani V, et al: Prevalence of 79. European Carotid Surgery Trialists’ Collaborative 36. Intensive blood-glucose control with sulphonyl-ureas atherosclerotic lesions at the carotid bifurcation in pa- Group: Randomized trial of endarterectomy for re- or insulin compared with conventional treatment tients with asymptomatic bruits: an echo-Doppler cently symptomatic carotid stenosis: final results of and risk of complications in patients with type 2 dia- (duplex) study. Angiology 36:235, 1985 the MRC European Carotid Surgery Trial. Lancet betes (UKPDS 33). UK Prospective Diabetes Study 59. Kartchner MM, McRae LP: Noninvasive evaluation 351:1379, 1998 (UKPDS) Group [published erratum appears in Lancet 354:602, 1999]. Lancet 352:837, 1998 and management of the “asymptomatic” carotid 80. Halliday A, Mansfield A, Marro J, et al: Prevention of bruit. Surgery 82:840, 1977 disabling and fatal strokes by successful carotid end- 37. Anderson KM,Wilson PW, Odell PM, et al: An up- 60. Clagett GP,Youkey JR, Brigham RA, et al: Asympto- arterectomy in patients without recent neurological dated coronary risk profile: a statement for health matic cervical bruit and abnormal ocular pneumo- symptoms: randomised controlled trial. MRC professionals. Circulation 83:356, 1991 plethysmography: a prospective study comparing two Asymptomatic Carotid Surgery Trial (ACST) Col- 38. Collaborative overview of randomised trials of anti- approaches to management. Surgery 96:823, 1984 laborative Group. Lancet 363:1491, 2004 platelet therapy—I. Prevention of death, myocardial 61. Wilson PWF, Hoeg JM, D’Agostino RB, et al: Cu- 81. Barnett JHM: Commentary: Carotid endarterecto- infarction, and stroke by prolonged antiplatelet thera- mulative effects of high cholesterol levels, high blood my. Lancet 363:1486, 2004 py in various categories of patients. Antiplatelet Trial- ists’ Collaboration [published erratum appears in pressure, and cigarette smoking on carotid stenosis. 82. Stroke Prevention in Atrial Fibrillation Study: Final BMJ 308:1540, 1994]. BMJ 308:81, 1994 N Engl J Med 337:516, 1997 results. Circulation 84:527, 1991 39. Hart RG, Halperin JL, McBride R, et al: Aspirin for 62. O’Leary DH, Polak JF, Kronmal RA, et al: Distribu- 83. Warfarin versus aspirin for prevention of thrombo- the primary prevention of stroke and other major vas- tion and correlates of sonographically detected carot- embolism in atrial fibrillation: Stroke Prevention in cular events: meta-analysis and hypotheses. Arch id artery disease in the Cardiovascular Health Study. Atrial Fibrillation II Study. Lancet 343:687, 1994 Neurol 57:326, 2000 The CHS Collaborative Research Group. Stroke 23:1752, 1992 84. Go AS, Hylek EM, Phillips KA, et al: Implications of 40. Kronmal RA, Hart RG, Manolio TA, et al: Aspirin stroke risk criteria on the anticoagulation decision in use and incident stroke in the cardiovascular health 63. Hennerici M, Aulich A, Sandmann W, et al: Inci- nonvalvular atrial fibrillation: the Anticoagulation and study. CHS Collaborative Research Group. Stroke dence of asymptomatic extracranial arterial disease. Risk Factors in Atrial Fibrillation (ATRIA) study. 29:887, 1998 Stroke 12:750, 1981 Circulation 102:11, 2000 41. Barnett HJM, Eliasziw M, Meldrum HE: Drugs and 64. Barnett HJ, Eliasziw M, Meldrum HE, et al: Do the 85. Hass WK, Easton JD, Adams HP Jr, et al: A random- surgery in the prevention of ischemic stroke. N Engl J facts and figures warrant a 10-fold increase in the ized trial comparing ticlopidine hydrochloride with Med 332:238, 1995 performance of carotid endarterectomy on asympto- aspirin for the prevention of stroke in high-risk pa- matic patients? Neurology 46:603, 1996 tients. Ticlopidine Aspirin Stroke Study Group. N 42. Hansson L, Zanchetti A, Carruthers SG, et al: Effects of intensive blood-pressure lowering and low-dose as- 65. Warlow C: Endarterectomy for asymptomatic carotid Engl J Med 321:501, 1989 pirin in patients with hypertension: principal results of stenosis? Lancet 345:1254, 1995 86. Creager MA: Results of the CAPRIE trial: efficacy the Hypertension Optimal Treatment (HOT) ran- 66. Amarenco P, Cohen A,Tzourio C, et al: Atheroscle- and safety of clopidogrel. Clopidogrel versus aspirin