Cardiac resynchronization therapy (CRT) via bi-ventricular pacing has demonstrated clinical benefits in heart failure (HF) patients with ventricular dyssynchrony. Other approaches of CRT is little known.This study assessed the feasibility, safety, and efficacy of left bundle branch area pacing (LBBAP) in HF patients with left bundle branch block (LBBB).Eleven consecutive HF patients with reduced left ventricular ejection fraction (LVEF) and LBBB and indicated for CRT were recruited. LBBAP was achieved via trans-ventricular septal approach and characterized by narrowed QRS duration (QRSd), shortened peak left ventricular activation time (LVAT) and right bundle branch conduction delay in electrocardiogram. Electrocardiogram, echocardiogram and cardiac function were evaluated at baseline and follow-up. Interventricular mechanical delay (IVMD) and 3D-tissue synchronization imaging (3D-TSI) during LBBAP and intrinsic LBBB status were measured by echocardiogram at follow-up.LBBAP significantly shortened QRSd (129.09±15.94 ms from native 180.00±15.86 ms, P <0.01) and LVAT (80.91±9.95 ms from native 108.18±15.54 ms, P <0.01). IVMD and the standard deviation of TSI of 12 left ventricular (LV) segments were significantly shorter during LBBAP than in intrinsic LBBB status (both with P <0.01). At average follow-up of 6.7 months, NYHA functional class, plasma levels of B-type natriuretic peptide, LV end systolic diameter and LVEF were significantly improved (all with P <0.05 vs. baseline).The study demonstrates that LBBAP is clinically feasible in patients with systolic HF and LBBB. LBBAP can be a new CRT to correct LBBB, provide ventricular synchrony and improve clinical symptoms with LV reverse remodeling.