Left ventricular ejection fraction is a determinant of cardiac performance after long-term conduction system pacing in patients with left bundle branch block?

OBJECTIVE

This study aims to explore the feasibility, safety, and clinical performance of conduction system pacing (CSP) in patients with left bundle branch block (LBBB) and varying left ventricular ejection fraction (LVEF) values.

METHODS

We consecutively enrolled all patients with LVEF ≤ 35% and LBBB who met the criteria for cardiac resynchronization therapy (CRT) and underwent CSP from January 2018 to December 2021. We compared the differences in improvements in cardiac performance after CSP between patients with LVEF < 25% and those with LVEF between 25 to 35%.

RESULTS

CSP was successfully deployed in 74 out of 80 patients (92.50%), including 32 patients with LVEF < 25% and 42 patients with LVEF 25%-35%. The CSP response rates were similar between the two groups (71.90% vs. 90.50%, P = 0.076), as were the super-response rates (62.50% vs. 78.60%, P = 0.129) and the rates of left ventricular complete reverse remodeling (21.90% vs. 42.90%, P = 0.059) after a follow-up period of 40.81 ± 11.93 months. Significant improvements were observed in LVEF (20.50 ± 2.75% vs. 37.78 ± 13.04%, P < 0.001), left ventricular end-diastolic dimension (LVEDD) (69.56 ± 6.77 mm vs. 59.41 ± 11.00 mm, P < 0.001), left ventricular end-systolic volume (LVESV) (224.81 ± 50.65 ml vs. 134.00 ± 83.35 ml, P < 0.001), NYHA class (3.59 ± 0.48 vs. 1.78 ± 0.66, P < 0.001), and QRS duration (168.75 ± 21.52 ms vs. 117.81 ± 17.09 ms, P < 0.001) in patients with LVEF < 25%. Despite these improvements, the final LVEF (37.78 ± 13.04 vs. 46.19 ± 9.47, P = 0.003) and final LVESV (134.00 ± 83.35 vs. 70.89 ± 38.89, P = 0.001) after CSP were inferior in patients with LVEF < 25%, and the rate of rehospitalization for heart failure was higher in this group (46.90% vs. 21.40%, P = 0.021) compared to those with LVEF between 25 to 35%.

CONCLUSIONS

CSP is feasible and safe for improving clinical outcomes in patients with LVEF < 25%. Timely CSP intervention in patients with LBBB and HF may be beneficial for cardiac performance.