Chest pain associated with rate-related left bundle branch block and cardiac memory mimicking ischemia

Abstract

BackgroundIntermittent left bundle branch block (LBBB) has been linked to chest pain, and causes cardiac memory electrocardiographic (ECG) changes mimicking ischemia. PurposeTo present a case of chest pain with ECG abnormalities suggestive of ischemia, both likely caused by LBBB. CaseA 33-year-old hypertensive female evaluated for chest pain and LBBB by ECG was treated with lisinopril and metoprolol, and scheduled for stress testing. A 12-lead ECG performed prior to the stress test, due to recurrence of the chest pain the preceding night, showed resolution of the LBBB with a lower heart rate, and T-wave inversions in the precordial leads suggestive of ischemia. She developed chest pains with reappearance of LBBB during stress testing, which prompted cardiac catheterization. This revealed normal coronaries and left ventricular systolic function. The ECG abnormalities were in retrospect likely due to cardiac memory. Her chest pains may have been caused by the intermittent, rate-related LBBB, as control of her heart rate and blood pressure with metoprolol and lisinopril improved her symptoms on follow-up. ConclusionIntermittent LBBB causes chest pain and electrocardiographic abnormalities suggestive of ischemia in the absence of obstructive coronary disease. Certain clinical and electrocardiographic features may provide clues to a non-ischemic etiology.<Learning objective: In the absence of obstructive coronary disease, rate-related left bundle branch block is associated with chest pain described as local, non-radiating, with palpitations and walk-through phenomenon. It can also cause electrocardiographic (ECG) changes of cardiac memory, which mimic myocardial ischemia, but with T waves that are positive in lead aVL, positive or isoelectric in lead I, and more inverted in the precordial leads compared with lead III. These clinical and ECG features may provide clues to non-coronary etiology of chest pain.>