Left bundle branch area pacing: stable parameters and preserved function at long-term follow-up

Introduction

Left bundle branch area pacing (LBBAP) is increasingly recognized as a physiological pacing technique that preserves left ventricular (LV) synchrony. This study aims to evaluate long-term stability of pacing, electrocardiographic, and echocardiographic parameters.

Methods

Single center retrospective study including consecutive patients who underwent LBBAP between 2021 and 2025. LBBAP criteria was defined as a right bundle branch block pattern in lead V1 and LV activation time (LVAT) of <90ms. Data on lead performance and electrocardiographic and echocardiographic parameters were obtained at implantation and at the final follow-up visit.

Results

A total of 298 patients were included [median age 79 (IQR 71-84) years, 66% (n=197) male]. The most common indications were atrioventricular (AV) node disease (59%, n=176), sinus node disease (18%, n=53) and biventricular cardiac resynchronization therapy (CRT) bailout (11%, n=32). Nineteen patients (6%) had undergone transcatheter aortic valve implantation prior to LBBAP implantation.

Procedural duration was 63 (IQR 50-80) minutes, with a fluoroscopy time of 5 (IQR 3-8) minutes. Median LVAT was 86 ms (IQR 76–93), paced QRS duration was 111 ms (IQR 100–120), and the interpeak V1–V6 interval was 38 ms (IQR 29–45). The acute R-wave amplitude reached 11.8 mV (IQR 7.4–16.6), and the pacing threshold was 0.5 V (IQR 0.5–0.7).

At a median follow-up of 11 months (IQR 5–22), lead parameters remained stable, with a pacing threshold of 0.6 V (IQR 0.5–0.8) and an R-wave amplitude of 12.2 mV (IQR 9.2–20.0). The paced QRS duration remained narrow at 120 ms (IQR 110–126). Only five procedure-related complications were reported: two cases of device-associated endocarditis, two cases of lead dislodgement, and one case of pericarditis.

In the subgroup of patients who underwent left ventricular ejection fraction (LVEF) assessment at 1-year follow-up (n=104), LVEF was preserved [60% (IQR 44–60) vs. 55% (IQR 50–60); p=0.485], with a ventricular pacing dependency of 95% (IQR 32–100) at follow-up. Among the 21 patients with a baseline LVEF<40%, most received LBBAP as a bailout CRT strategy, and 13 (62%) demonstrated an improvement in LVEF>40% at follow-up [median LVEF 32% (IQR 26-35) vs 42% (35-50), p=0.001].

Conclusion

At a median follow-up of 11 months, lead parameters were stable and QRS duration was narrow. In the subgroup of patients who underwent echocardiographic evaluation at 1-year follow-up, LVEF was preserved. Moreover, 62% of patients with previously reduced LVEF demonstrated improvement in LVEF.