Background: The impact of left bundle branch area pacing (LBBAP) on right ventricular (RV) function and tricuspid regurgitation (TR) remains unclear.

Objective: We aimed to assess the long-term effects of LBBAP on RV performance and on TR.

Methods: RV function was evaluated using RV free wall strain, tricuspid annular plane systolic excursion, fractional area changing, and systolic velocity of the lateral tricuspid annulus. The presence of reverse septal flash (RSF) and basal bulge (BB) was used to assess RV motion pattern. The distance between the lead entry site on the interventricular septum and the septal leaflet of the tricuspid annulus (lead-TV distance) was measured.

Results: The analysis included 122 subjects [62 men (50.8%); mean age 76.5 ± 11.4 years] with a median follow-up of 21 months (18-24.5 months). During follow-up, RV free wall strain improved significantly (15.2 ± 5.8 vs 16.4 ± 5.5; P < .001) while tricuspid annular plane systolic excursion, systolic, and fractional area changing remained unchanged. Left ventricular ejection fraction was an independent predictor of improved RV function (B = 3.51; 95% confidence interval 1.39-8.9; P = .01). With LBBAP, RSF disappeared in 22 of 23 patients (96%) and BB in 15 of 22 patients (68%) in whom RSF and BB were present at baseline, respectively. RV function improvement was significantly higher when RSF was present at baseline (14 patients vs 11 patients; P = .02). At follow-up, no significant deterioration in TR occurred for the overall group. However, a lead-TV distance of <24.5 mm was associated with TR progression.

Conclusion: LBBAP has a favorable impact on RV function. A basal LBBAP position is associated with worsening TR.