BACKGROUND Cardiac resynchronization therapy (CRT) via biventricular pacing has demonstrated clinical benefits in patients with heart failure (HF) and ventricular dyssynchrony. Other approaches of CRT is little known. OBJECTIVE The purpose of this study was to assess the feasibility, safety, and efficacy of left bundle branch area pacing (LBBAP) in patients with HF and left bundle branch block (LBBB). METHODS Eleven consecutive patients with HF, reduced left ventricular ejection fraction and LBBB and indicated for CRT were recruited. LBBAP was achieved via transventricular septal approach and characterized by narrower QRS duration, shortened peak left ventricular activation time, and right bundle branch conduction delay on the electrocardiogram. Electrocardiogram, echocardiogram, and cardiac function were evaluated at baseline and follow-up. Interventricular mechanical delay and 3-dimensional tissue synchronization imaging during LBBAP and intrinsic LBBB status were measured by echocardiography at follow-up. RESULTS LBBAP significantly shortened QRS duration (from baseline 180.00 6 15.86 ms to 129.09 6 15.94 ms; P , .01) and left ventricular activation time (from baseline 108.18 6 15.54 ms to 80.91 6 9.95 ms; P , .01). Interventricular mechanical delay and the standard deviation of tissue synchronization imaging of 12 left ventricular (LV) segments were significantly shorter during LBBAP than in intrinsic LBBB status (both with P , .01). At a mean follow-up period of 6.7 months, New York Heart Association functional class, plasma level of B-type natriuretic peptide, LV end-systolic diameter, and left ventricular ejection fraction were significantly improved (all with P , .05 vs baseline). CONCLUSION The study demonstrates that LBBAP is clinically feasible in patients with systolic HF and LBBB. LBBAP can be a new CRT technique to correct LBBB, provide ventricular synchrony, and improve clinical symptoms with LV reverse remodeling.