Rate-Dependent Painful Left Bundle Branch Block (PLBBB) in a Structurally Normal Heart.

Painful left bundle branch block (PLBBB) is a rare and often underdiagnosed cause of exertional chest pain in patients without structural heart disease or coronary obstruction. We report the case of a woman in her fifties with well-controlled hypertension and no family history of sudden cardiac death, who presented with exertional chest tightness. During an exercise stress test, her typical symptoms appeared concurrently with a transient, rate-dependent LBBB, which resolved during recovery with normalization of the QRS. Cardiac biomarkers, echocardiography, and coronary angiography were normal, confirming a structurally normal heart. Beta-blocker therapy led to marked symptomatic improvement and good tolerance to a structured exercise program. Rate-dependent PLBBB is a benign but clinically relevant conduction disturbance that can mimic myocardial ischemia. Recognition of this entity is essential to avoid unnecessary invasive investigations and to guide appropriate management focused on heart rate control and symptom relief.