Preservation of left ventricular ejection fraction with left bundle branch area pacing

Left bundle branch area pacing (LBBAP) has emerged as an effective ventricular pacing strategy aiming to maintain physiological conduction, and potentially preserving ventricular function. While procedural aspects and lead parameter stability have been well documented, the echocardiographic impact of LBBAP, particularly on left ventricular ejection fraction (LVEF), remains underexplored. This study aims to evaluate the mid-term effects of LBBAP on LVEF.

Single-center, retrospective study including patients who underwent LBBAP from 2021 to 2023. LBBAP was performed with the goal of achieving a right bundle branch block pattern in lead V1 during pacing and LV activation time (LVAT) of <85ms. Baseline and follow-up LVEF were collected and compared using the Wilcoxon signed-rank test. Procedural characteristics, including lead parameters, were also recorded.

From a series of 112 consecutive patients submitted to physiological pacing, a total of 42 patients had an echocardiographic evaluation at 18 months (IQR 11-27); median age of 76 years (IQR 69-82) and 62% were male. Most patients (64%) had no history of cardiomyopathy, while the remaining had ischemic (17%) or non-ischemic cardiomyopathy (19%). The most frequent indication for pacing was complete atrioventricular block (52%), followed by failure of biventricular cardiac resynchronization therapy (19%). Median baseline LVEF was 60% (IQR 40-60%): 15 patients had reduced LVEF and 27 had preserved LVEF. Median implantation duration was 57 minutes (IQR 50-80), and fluoroscopy time was 5 minutes (IQR 3-8). The median post-procedural LVAT was 86 ms (IQR 81-98), with an acute R-wave amplitude of 14.5 mV (IQR 7.3-18.7) and a pacing threshold of 0.5 V (IQR 0.4-0.7). One periprocedural complication was reported, involving post-pacemaker implantation pericarditis.

At follow-up, LVEF did not differ significantly from baseline (60% [IQR 40-60%] vs. 57% [IQR 48-60%], P=0.861). Ventricular pacing dependency was 60% (IQR 8–98). Notably, 6 out of 10 patients (60%) with reduced baseline LVEF showed improvement, achieving an LVEF of >40% at follow-up.

In this cohort, LVEF did not differ significantly following LBBAP implantation in the mid-term. Most patients with reduced baseline LVEF showed improved ventricular function. These findings suggest potential benefits of LBBAP, warranting further validation in larger studies.