Cardiac resynchronization therapy via left bundle branch area pacing and a dual-chamber ICD; a CROSS-LEFT substudy

FUNDING ACKNOWLEDGEMENTS: Type of funding sources: None. BACKGROUND: Left bundle branch area pacing (LBBAP) has emerged as a promising technique to deliver cardiac resynchronization therapy (CRT). PURPOSE: We sought to evaluate the feasibility of a single LBBAP lead connected to a dual-chamber ICD in patients indicated with a CRT-D implantation. METHODS: The CROSS-LEFT study prospectively included consecutive sinus rhythm patients with a reduced ejection fraction and a complete left bundle branch block. A DF-1 lead was implanted at the right ventricular apex, and an LBBAP lead through the interventricular septum. Patients were implanted with a dual-chamber DF-1 defibrillator (ICD) connected to the atrial lead (RA port), the LBBAP lead (RV IS-1 port), and the defibrillation lead (RV DF-1 port), the IS-1 pin being capped. Atrioventricular delay was optimized to ensure fusion between LBBAP and native conduction from the right bundle. Patients were followed during 6 months. RESULTS: A total of 22 patients were included (median age 68 years, 77% male, 41% ischemic). LBBAP resulted in a significant reduction of median QRS width from 161 to 128ms (p<0.0001). At 6 months, median ventricular sensing was 18mV (range 5–31, IQR 9), and LBBAP threshold 0.5V (range 0.25–0.75, IQR 0). Median LVEF significantly improved from 27 to 45% at 6 months (p<0.0001), with a median reduction of LV end-systolic volume of 32% (p=0.0002), 67% of patients being considered as super-responders. CONCLUSION: In patients with a left bundle branch block indicated with a biventricular defibrillator, CRT can be safely and efficiently performed via a single LBBAP lead connected to a dual-chamber ICD, and is associated with significant electromechanical reverse remodeling.