Abstract
BACKGROUND: We aimed to evaluate if optimization by maximizing QRS duration (QRSd) reduction is feasible in an all-comer cardiac resynchronization therapy (CRT) population, and if reduced, QRSd is associated with a better clinical outcome. METHODS: Patients with LBBB receiving CRT implants during the period 2015-2020 were retrospectively evaluated. Implants from 2015-2017 were designated as controls. Starting from 2018, an active 12-lead electrogram-based optimization of QRSd reduction was implemented (intervention group). QRSd reduction was evaluated in a structured way at various device AV and VV settings, aiming to maximize the reduction. The primary endpoint was a composite of heart failure hospitalization or death from any cause. RESULTS: A total of 254 patients were followed for up to 6 years (median 2.9 [1.8-4.1]), during which 82 patients (32%) reached the primary endpoint; 53 deaths (21%) and 58 (23%) heart failure hospitalizations. Median QRS duration pre-implant was 162 ms [150-174] and post-implant 146ms [132-160]. Mean reduction in QRS duration was progressively larger for each year during the intervention period, ranging from - 9.5ms in the control group to - 24 in the year 2020 (p = 0.005). QRS reduction > 14 ms (median value) was associated with a lower risk of death or heart failure hospitalization (adjusted HR 0.54 [0.29-0.98] (p = 0.04). CONCLUSIONS: Implementing a general strategy of CRT device optimization by aiming for shorter QRS duration is feasible in a structured clinical setting and results in larger reductions in QRS duration post-implant. In patients with a larger QRS reduction, compared to those with a smaller QRS reduction, there is an association with a better clinical outcome.