Unmasking a Hidden Bridge: Exercise-Induced Right Bundle Branch Block Without Ischemia

Myocardial bridging (MB) is usually benign but may occasionally be associated with ischemia or arrhythmias. Exercise induced conduction abnormalities are rare and poorly understood.

A 69-year-old asymptomatic male developed transient right bundle branch block (RBBB) at peak exertion during treadmill stress testing, without angina, ischemic ECG changes, or hemodynamic instability. The RBBB resolved immediately during recovery. Coronary computed tomography angiography identified a superficial myocardial bridge of the mid-left anterior descending artery without luminal narrowing or atherosclerosis.

The findings supported a benign, rate dependent conduction delay rather than ischemia.

This case illustrates a rare coexistence of MB with exercise-induced RBBB and highlights the importance of recognizing nonischemic conduction phenomena to avoid unnecessary invasive studies.