The Predictive Value of Baseline Concordant Left Bundle Branch Block Morphology for Success Rate and Clinic Outcomes in Left Bundle Branch Pacing.

BACKGROUND

The left bundle branch block (LBBB) morphology could be divided into concordant LBBB (con-LBBB; T waves concordant with QRS) or discordant LBBB (dis-LBBB; T waves discordant with QRS) types on the basis of the direction of T and QRS main waves except for true or non-true LBBB (non-tLBBB). In this study we aimed to investigate the influence of baseline LBBB morphology on success rate of left bundle branch pacing (LBBP), echocardiographic response, and clinical outcomes in patients who received LBBP-delivered cardiac resynchronization therapy.

METHODS

Consecutive patients with heart failure (HF) and LBBB who attempted to receive LBBP-delivered cardiac resynchronization therapy were prospectively enrolled from 2019 to 2024. Baseline LBBB morphology was identified as con-LBBB, dis-LBBB, and non-tLBBB types. The primary end point was echocardiographic response at 6-month follow-up. Secondary end points included: (1) LBBP success; (2) echocardiographic super-response; (3) all-cause mortality and/or HF hospitalization.

RESULTS

A total of 110 patients (32 with con-LBBB, 31 with dis-LBBB, and 47 with non-tLBBB) post cardiac resynchronization therapy were included. The LBBP success rate was highest in the con-LBBB group, followed by the dis-LBBB, and non-tLBBB group (84.4% vs 71.0% vs 51.1%; P = 0.007). After adjusting for confounders, con-LBBB was an independent predictor for LBBP success (odds ratio [OR], 3.90 [95% confidence interval (CI), 1.21-12.51]; P = 0.022), echocardiographic response (OR, 4.88 [95% CI, 1.26-18.81]; P = 0.021), and super-response (OR, 3.87 [95% CI, 1.40-10.69]; P = 0.009). During a mean follow-up of 20.2 ± 12.9 months, con-LBBB was associated with decreased all-cause mortality or HF hospitalization (hazard ratio, 0.08 [95% CI, 0.01-0.62]; P = 0.015).

CONCLUSIONS

Baseline con-LBBB might be a useful predictor for LBBP success and favourable clinical outcomes.