Early left bundle branch pacing in heart failure with mildly reduced ejection fraction and left bundle branch block

Background Left bundle branch pacing (LBBP) achieves resynchrony and improves cardiac function in heart failure (HF) patients with reduced ejection fraction (EF) by correcting left bundle branch block (LBBB). Few data studied the efficacy of early LBBP in HF with mildly-reduced EF (HFmrEF) and LBBB. Objective To explore the efficacy of early LBBP in patients with HFmrEF and LBBB. Methods Consecutive patients with HFmrEF (LVEF 35%-50%) and LBBB were prospectively enrolled to receive LBBP (Early-LBBP group) plus guideline-directed medical therapy (GDMT) or GDMT alone (GDMT group). Study outcomes included changes in LVEF, LV end diastolic diameter (LVEDD), NYHA classification and NT-ProBNP, and clinical events (HF rehospitalization or syncope). A subgroup analysis compared efficacy of LBBP between patients with LBBB only without comorbidities or late gadolinium enhancement (LGE)(LBBB-Only group) and patients with either comorbidities or LGE (LBBB-Combined group). Results Fifty-four patients were enrolled and analysis included 37 in Early-LBBP and 15 in GDMT group. LBBP achieved greater improvement in LVEF (+14.75±7.37% vs. -2.42±2.84%, p<0.001), reduction of LVEDD (-7.51±5.40 vs. -0.87±4.36mm, p<0.001) and NYHA classification (-0.84±0.76 vs. -0.13±0.74, p=0.004), and similar reduction of NT-proBNP (-408.83±920.29pg/ml vs. -229.05±1579.17pg/ml, p=0.610) at 6-month. Early LBBP showed significantly reduced clinical events (0.0% vs. 40.0%, p<0.001) after 20.68±13.55 month follow-up. Subgroup analysis showed patients in LBBB-Only group benefited more from LBBP in LVEF improvement and LVEDD reduction compared with LBBB-Combined group. Conclusion Early LBBP with GDMT demonstrated greater improvement of cardiac function and reduced clinical events compared to GDMT alone in patients with HFmrEF and LBBB.