Echocardiographic response from Left Bundle Branch Area Pacing Optimized Cardiac Resynchronization Therapy (LOT-CRT) versus traditional CRT.

Background: Traditional cardiac resynchronization therapy (CRT) with biventricular pacing (BVP) may be less effective in patients with nonspecific intraventricular conduction delay (NIVCD). Left bundle branch area pacing (LBBAP) combined with LV coronary venous lead pacing (LOT-CRT) may be more effective in these patients.

Objective: We assessed the echocardiographic response of LOT-CRT in patients with left bundle branch block (LBBB) or NIVCD and compared to a propensity-matched BVP cohort.

Methods: Patients with conventional CRT indications and preferentially NIVCD were recruited. Echocardiographic parameters, including absolute %change in LV ejection fraction (LVEF) and relative %change in LV end-systolic volume (LVESV), were evaluated at implantation and 6-month follow-up. The BVP cohort was from an independent study, selected using 1:1 propensity-matching. LOT-CRT patients were subclassified into "successful LOT-CRT" (LBBAP; presence of r' in electrode ECG V1) and "DOT-CRT" (functional deep septal capture).

Results: LOT-CRT patients (N=34; age 64, female 38%, NIVCD 47%, LBBB 53%, ICM 21%, QRSd 175 ms and LVEF 27.6%) had significantly greater LVEF improvement (16.1% vs 6.1%;P<0.01) and LVESV reduction (-43.5% vs -20.9%;P<0.01) compared to BVP patients. After adjusting for baseline characteristics, LOT-CRT patients still had significantly greater LVEF improvement (7.5%;P<0.01) and LVESV reduction (18.4%;P<0.01) than BVP patients. Response was consistent across LBBB and NIVCD subgroups. LOT-CRT patients with QRS≥171 ms showed greater benefit (P=0.04; both LVEF and LVESV). No significant differences were observed between successful LOT-CRT and DOT-CRT.

Conclusions: LOT-CRT resulted in superior LVEF and LVESV improvements compared to BVP in NIVCD and LBBB patients, and enhances CRT response.