Unmasking Coronary Artery Disease With Intermittent Left Bundle Branch Block: A Case Report

Intermittent left bundle branch block (LBBB) is an unusual phenomenon, with very few cases documented in the literature. It is often considered a reflection of underlying conditions known to increase the risk of cardiovascular morbidity and death, including coronary artery disease (CAD), cardiomyopathy, hypertensive heart disease, and aortic valve disease. In rare instances, coronary vasospasm is the sole underlying condition. It is typically diagnosed by ECG and managed according to the underlying cause. We describe a case of intermittent LBBB presenting with chest pain. The ECG showed dynamic changes with transient/intermittent LBBB. An angiogram was performed, revealing significant coronary lesions. The patient was eventually managed conservatively and discharged on dual antiplatelet therapy for a duration of one year with a one-month clinic follow-up where his condition improved. Intermittent LBBB represents a transient disturbance in the intraventricular conduction system, where diseased conduction occurs secondary to an underlying cause, but normal conduction eventually restores. This results in complexes where LBBB appears alongside normally conducted beats in a single ECG tracing. There is limited knowledge about the prognosis of patients with intermittent LBBB; therefore, patients with LBBB should undergo careful evaluation due to the known association with serious cardiac pathologies, particularly cardiac ischemia. It is important to consider the potential adverse effects on ventricular function.