Mp-453089-5 clinical benefits of early left bundle branch pacing in heart failure with mildly reduced ejection fraction and left bundle branch block

Patients with heart failure with mildly-reduced ejection fraction (HFmrEF) and left bundle branch block (LBBB) have worse outcomes than those without intraventricular conduction abnormality. Current guidelines only recommend cardiac resynchronization therapy (CRT) when LVEF is less than 35%. Left bundle branch pacing (LBBP) has been shown to better restore electrical synchrony and improve cardiac function than conventional biventricular CRT in HFrEF. Its efficacy in HFmrEF is rarely reported. The aim of this study is to evaluate the clinical benefits of early LBBP-CRT in patients with HFmrEF and LBBB in addition to guideline-directed medical therapy (GDMT) and to compare its efficacy to GDMT alone. Consecutive patients with HFmrEF (LVEF 35%-50%) and LBBB who received successful LBBP-CRT were prospectively enrolled from June 2018 to May 2022. All patients were titrated to maximally tolerated GDMT (BB, ACEI/ARB/ARNI, MRA, and SGLT2i) in addition to LBBP and were followed for at least 6 months (Early-LBBP group). For comparison, a group of patients with HFmrEF and LBBB were titrated to maximally tolerated GDMT without early LBBP-CRT (GDMT group). A total of 38 patients were included in the Early-LBBP group and 13 in the GDMT group. LVEF significantly increased from baseline 39.09±3.63% to 53.47±6.81% (p<0.001) in Early-LBBP group at 6 months compared to from 37.79±3.30% to 35.79±5.68% (p=0.08) in GDMT group. The changes in mean LVEF between two groups showed statistical significance (+14.38±7.45% vs -2.00±4.28%, p<0.001). Similarly, significant improvements were also observed in LV end-diastolic diameter (LVDd) (-7.39±5.43mm vs -1.00±4.67mm, p<0.001) and NYHA class (-0.89±0.69 vs -0.31±0.95, p=0.02). In the Early-LBBP group, QRS duration decreased from 170.68±16.71 ms to 131.45±15.75 ms (p<0.001) and mean LVAT was 71.55±10.45 ms, with stable thresholds and impedances at follow up. After a median follow-up of 11.67 months, five HF rehospitalizations and one syncope event occurred in the GDMT group. No HF rehospitalization, syncope or death occurred in the Early-LBBP group during median 19.70 months follow-up. In patients with HFmrEF and LBBB, early LBBP-CRT in addition to GDMT can significantly improve cardiac function and clinical symptoms and reverse LV remodeling compared to GDMT alone. Patients with HFmrEF and LBBP may potentially benefit from LBBP-CRT earlier than current guideline recommendations.