Chest pain and exercise induced left bundle branch block – A clinical dilemma

Exercise-induced left bundle branch block is a rare electrocardiographic phenomenon. We present two patients with angina pectoris who developed left bundle branch block on ECG during treadmill test. The first patient had non-obstructive coronary arteries with slow flow and is a rarely reported entity. The second patient had typical chest pain with single vessel Coronary Artery Disease. Left bundle branch block occurred in stage I of Treadmill Testing and persisted for approximately 4 hours and then reverted spontaneously. These two interesting cases of this rare phenomenon are presented here with review of relevant literature.