Exercise-induced left fascicular block: A forgotten sign of coronary disease.

A 55-year-old patient presented with stable angina pectoris with normal physical examination on rest electrocardiogram and cardiac echocardiogram. Treadmill test revealed exercise-induced left posterior fascicular block, which is an uncommon and easily unnoticed marker of coronary artery disease. A dobutamine stress echocardiogram was performed, with a clearly positive result. Coronary angiography revealed critical stenosis in the right coronary artery.