Left bundle branch area pacing induced dual bundle branches non-reentrant bigeminy and Takotsubo cardiomyopathy: a case report

A 76-year-old woman with intermittent advanced atrioventricular block from a previous left septal accessory pathway and atrioventricular (AV) nodal slow pathway ablation for supraventricular tachycardia was referred for pacing. Her echocardiogram showed no structural abnormality and preserved left ventricular ejection fraction (LVEF). Left bundle branch area pacing (LBBaP) was achieved successfully, although frequent premature ventricular complexes (PVCs) were observed during the procedure. In the interrogation before discharge, asymptomatic ST-segment elevation on the precordial electrocardiogram (ECG) necessitated an emergent coronary angiography. No significant stenosis or spasm of coronary arteries was found, while left ventriculography revealed apical dyskinesis suggestive of Takotsubo cardiomyopathy. On closer inspection, frequent monomorphic PVCs developed after each pacing beat and formed a regular bigeminy pattern, indicating rapid LBB stimulation, and the facilitated slow conduction along the adjacent bundle branches induced the dual ventricular response. The resultant frequent desynchronized ventricular activation may have contributed to the stress for cardiac decompensation. Beta blocker was titrated to alter the critical time period matched for the repetitive activation pattern and to suppress sympathetic tension. The bigeminy was eliminated ultimately, and repositioning of the lead was avoided. The ventricular wall motion and LVEF recovered within months. This case highlights the importance of close observation of electrocardiographic monitoring after pacing. Despite the potential benefits for future cardiac function and lower pro-arrhythmic effect than routine pacing modalities, LBBaP may still be associated with new-onset arrhythmia and myocardial injury considering the baseline impairment of the electrical or anatomical substrate. Individualized management should be tailored according to specific scenarios.