Permanent Left Bundle Branch Area Pacing Improves Mitral Regurgitation and Cardiac Function in Patients with Right Bundle Branch Block

Abstract Background Permanent left bundle branch area pacing (LBBAP) can correct left bundle branch block. However, the correction of LBBAP in the right bundle branch block (RBBB) is undefined. Objective To investigate the effect and safety of permanent LBBAP in patients with RBBB. Methods Ninety-two consecutive patients who successfully experienced permanent LBBAP were recruited from May. 2019 to Dec. 2022 in our single center. Twenty patients with RBBB were analyzed in our study. They were followed up at 1, 3, 6 and 12 months after the LBBAP procedure. The QRS duration (QRSd) on the V1 lead of the 12-lead electrocardiogram was measured and compared before and after the LBBAP procedure, as well as left ventricular ejection (LVEF) and mitral regurgitation via echocardiography. The acute pitfills and delayed complications of the LBBAP procedure were recorded to assess safety. Results . The mean age of the RBBB patients was 66.35 ± 11.55 years, 60% were male, 75% had severe AVB, 20% had SSS, 25% had heart failure, 30% had atrial fibrillation, 45% had coronary heart diseases, 35% had hypertension, and 15% had diabetes mellitus. The average operation time of the LBBAP procedure was 106.53 ± 2.72 min, with 9 patients (45%) needing temporary cardiac pacing during surgery. QRS duration was significantly narrowed in RBBB patients after the LBBAP procedure (132.60 ± 31.49 vs. 119.55 ± 18.58 ms, P = 0.046 ). The average LVEF at the 12-month follow-up increased significantly from 55.15 ± 10.84% to 58.5 ± 10.55% ( P = 0.018 ), with the median mitral regurgitation alleviated from 4.46 (0.9, 7.3) to 2.29 (0, 3.49) cm 2 ( P = 0.033 ). No ventricular septum perforation or pericardial effusion was found during the LBBAP procedure or follow-up. Conclusion LBBAP can shorten the QRS duration in patients with RBBB immediately, with mitral regurgitation and cardiac function improving during the 12-month follow-up.