Left ventricular outflow tract obstruction following left bundle branch area pacing: a case report

Background: Left bundle branch area pacing (LBBAP) is a physiological pacing strategy considered safe in non-obstructive hypertrophic cardiomyopathy (HCM). Its effect on left ventricular outflow tract (LVOT) obstruction in anatomically predisposed patients remains unclear. Case summary: A 76-year-old woman underwent LBBAP for atrioventricular nodal dysfunction. One week later, she developed chest pain and elevated troponin, despite unobstructed coronaries. Echocardiography revealed a resting LVOT gradient of 112.6 mmHg. Bipolar low-voltage pacing worsened the gradient, while unipolar high-voltage pacing reduced it to 15 mmHg, with symptom relief and improved global longitudinal strain. Discussion: This case illustrates a rare interaction between pacing configuration and LVOT dynamics. It emphasizes the need to recognize pacing-induced obstruction, particularly in patients with septal hypertrophy or mitral anomalies, and to adjust programming accordingly.