Effect of left bundle branch pacing on right ventricular function: A 3-dimensional echocardiography study.

Background: The effect of left bundle branch pacing (LBBP) on right ventricular (RV) function is not well known, and there is conflicting evidence regarding whether cardiac resynchronization therapy improves RV function.

Objectives: The study aimed to investigate the effect of LBBP on RV function and to evaluate the response of RV dysfunction (RVD) to LBBP.

Methods: Sixty-five LBBP candidates were prospectively included in the study and underwent echocardiography at baseline and 6-month follow-up. LBBP response was left ventricular (LV) reverse remodeling, defined as a reduction in LV end-systolic volume of ≥15% at follow-up.

Results: Patients were assigned to 2 subgroups on the basis of 3-dimensional echocardiography-derived RV ejection fraction (EF) before LBBP implantation: 30 patients (46%) in the no RVD group and 35 patients (54%) in the RVD group. The RVD group was characterized by higher N-terminal pro-brain natriuretic peptide levels, New York Heart Association functional class, and larger LV/RV size. LBBP induced a significant reduction in QRS duration, LV size, and improvement in LVEF and mechanical dyssynchrony in both the no RVD and RVD groups, and a significant improvement in RV volumes and RVEF in the RVD group (all P<.01). LBBP resulted in a similar percentage reduction in QRS duration, LV dimensions, LV volumes, and percentage improvement in LVEF in RVD and no RVD groups (all P＞.05). LV reverse remodeling (29 of 35 patients vs 27 of 30 patients; P = .323) in the RVD group was similar to that in the no RVD group after LBBP.

Conclusion: LBBP induces excellent electrical and mechanical resynchronization, with a significant improvement in RV volumes and function. RVD did not diminish the beneficial effects on LV reverse remodeling after LBBP.