This document summarizes research on right bundle branch block (RBBB) in patients presenting with acute coronary syndrome (ACS). It finds that RBBB in ACS patients identifies a high-risk group with worse short- and long-term outcomes. The presence of RBBB in AMI is associated with more complex cases and obstructive coronary artery disease as well as higher rates of complications and mortality. Studies found 30-day mortality was 14% for AMI patients with RBBB compared to 2% for those without.