Left bundle branch pacing optimized cardiac resynchronization therapy - Dawn of a new era in individualized cardiac resynchronization

Background/Introduction

Left bundle branch area pacing (LBBAP)–optimized (LOT) pacing modalities are emerging therapeutic strategies for cardiac resynchronization therapy (CRT). Both LOT-ICD and LOT-CRT approaches might have key roles in the future of resynchronization, but evidence guiding device selection for the individual patient remains limited in the absence of randomized trial results.

Purpose

This study aimed to compare clinical and echocardiographic outcomes between conduction system pacing–based CRT (CSP-CRT) and conventional biventricular CRT (Biv-CRT), and to identify predictors of response within the CSP-CRT cohort.

Methods

In this observational study, 51 consecutive patients with standard CRT indication underwent CSP-CRT procedure. Inverse probability of treatment weighting (IPTW) was applied to balance covariates between CSP-CRT and Biv-CRT cohort (n = 60). The CSP-CRT group was further divided into LOT-CRT (n = 27) and LOT-ICD (n = 24) subgroups. Follow-up was 24 months. The primary endpoint was comparison of composite of all-cause mortality and heart failure hospitalization; the secondary endpoint was comparison of echocardiographic response between groups.

Results

Baseline characteristics were not statistically different between CSP-CRT and Biv-CRT groups. Compared with LOT-ICD, LOT-CRT patients had larger LVEDD (65 ± 9 mm vs. 57.8 ± 7 mm; p = 0.035), worse NYHA class (3.0 ± 0.5 vs. 2.8 ± 0.6; p = 0.032), and a higher prevalence of prior myocardial infarction (14 vs. 8; p = 0.028).

LOT-CRT achieved greater paced QRS narrowing (41 ± 16 ms vs. 32 ± 14 ms vs. 28 ± 18 ms; p = 0.024), while V6 RWPT did not differ significantly between LOT-CRT and LOT-ICD but was shorter than in Biv-CRT. LOT-CRT and selected LOT-ICD patients without septal scar on MRI had improved clinical outcomes (log-rank p = 0.016). Perioperative reductions in V6 RWPT and paced QRS duration predicted lower event rates during follow-up period (AUC = 0.891, 95% CI: 0.82–0.95; p < 0.001).

Echocardiographic improvement was greater in LOT-CRT, with higher LVEF gain (13.3 ± 4.5% vs. 10 ± 4% vs. 8.5 ± 7.4%; p = 0.045) and larger LVESD reduction (20.5 ± 5% vs. 16.4 ± 4.8% vs. 16.5 ± 3%; p = 0.001). Multivariate analysis showed that LOT-CRT was an independent predictor of echocardiographic super-response (OR = 11.35, 95% CI: 1.58–82.5; p = 0.006).

Conclusions

In this observational cohort, LOT-CRT implantation was associated with superior clinical outcomes and more favorable echocardiographic remodeling compared with LOT-ICD or conventional Biv-CRT. These findings underscore the importance of preoperative cardiac MRI and detailed scar burden assessment to guide individualized device selection in cardiac resynchronization therapy.Figure 1.Figure2.