Left bundle branch block (LBBB) is a conduction abnormality with a prevalence of 0.2-2% that is commonly caused by myocardial infarction, coronary artery disease, hypertension, and cardiomyopathies. LBBB can occur transiently due to tachycardia, exercise, or other acute conditions. It involves delayed conduction in the left ventricle that can persist until heart rate slows. Patients with LBBB require cardiac evaluation and have a poorer prognosis, especially those with underlying heart failure or myocardial infarction who are at higher risk for underdiagnosis and lack of reperfusion therapy.
