Pacing strategies in the LVEF 35–50% grey area: LBBAP vs CRT

Introduction

In patients with moderately reduced left ventricular ejection fraction (LVEF 35–50%) who require ventricular pacing, right ventricular pacing can induce ventricular dyssynchrony and increase the risk of left ventricular dysfunction. Current expert consensus recognize both CRT and conduction system pacing as viable options. Left bundle branch area pacing (LBBAP) provides a more physiological ventricular activation and may offer advantages over conventional CRT in selected patients, but real-world comparative data on electrical, structural and clinical outcomes are still scarce.

Purpose

To compare procedural, electrical, echocardiographic and clinical outcomes between LBBAP and CRT in a real-world cohort of patients with bradycardia pacing indication and LVEF 35-50%.

Methods

A retrospective, single-center study was conducted including 37 patients who underwent either LBBAP (n=20) or CRT (n=17) implantation. Baseline characteristics, procedure metrics and complications were recorded. Electrocardiographic, echocardiographic and clinical parameters were evaluated at baseline and follow-up.

Results

Baseline clinical parameters were similar between groups. Procedural duration, fluoroscopy time and complication rates were similar. Mean baseline QRS duration was similar (133±32ms for LBBAP and 135±27ms for CRT, p=ns) although LBBAP resulted in greater QRS shortening (–19.3±24.9 ms) compared with CRT (+4.5± 33.3 ms, p=0.033).

Mean baseline left ventricular ejection fraction (LVEF) was also similar between groups (39±4% for LBBAP and 37±2% for CRT). Improvements in LVEF were nearly identical (+8.0±8.4% with LBBAP vs +7.7±8.9% with CRT; p=0.920), as were changes in GLS (–0.9±3.6% vs –1.0±1.7%; p=0.969).

Left ventricular volumes showed parallel reductions without significant differences between groups. Atrial and diastolic parameters including ΔLAVI, ΔE/e’ and ΔPASP demonstrated variable but comparable patterns. Clinically, no significant differences were observed between strategies and changes in NYHA class were similar and did not reach statistical significance (+0.3±0.8 with LBBAP vs -0.4±0.6 with CRT, p=0.08).

Conclusions

In patients with LVEF 35–50% requiring ventricular pacing, LBBAP demonstrated a safety profile comparable to CRT and provided markedly superior electrical resynchronization; however, this did not translate into significant differences in structural remodeling or clinical outcomes. These findings support LBBAP as a robust physiological pacing strategy and a viable and cheaper alternative to conventional CRT in everyday practice.Figure 1