Optimization of nonresponders to left bundle branch area pacing using electrical dyssynchrony mapping

Left bundle branch area pacing (LBBAP) is a new approach to resynchronization in patients with heart failure (HF). Treatment of LBBAP nonresponders by optimizing programming has not been studied.

This study aimed to assess the effects of optimization on left ventricular (LV) size and systolic function in LBBAP nonresponders.

We studied 41 patients with systolic HF and attempted LBBAP 6.5 ± 4.3 months post-implantation. Nonresponders (pre-cardiac resynchronization therapy [CRT] ejection fraction [EF] < 45% and increase in EF < 5%) and incomplete responders (increase in EF > 5% but final EF < 45%) to LBBAP were included. Electrical dyssynchrony was assessed using a novel measure called cardiac resynchronization index (CRI). Patients with R waves in V1 were classified as left bundle branch pacing (LBBP) and those without R waves in V1 as deep septal pacing. Patients were programmed to optimal atrioventricular delay, ventricular-ventricular delay, and pacing mode (LBBAP-only, biventricular, or LV-only). Echocardiograms before CRT, before optimization, and 8.2 ± 4.4 months after optimization were read in blinded fashion.

Most patients had LV leads (90.2%). LBBP was present in 41.5% and deep septal pacing in 58.5% of patients. CRI increased from 59.8% ± 25.9% to 84.5% ± 16.7%. CRT optimization significantly improved LV EF from 34.0% ± 7.0% to 37.0% ± 6.4% (P < .0001), end-systolic volume from 83.1 ± 38.9 to 72.7 ± 35.5 mL (P < .001), end-diastolic volume from 124.9 ± 46.3 to 112.9 ± 46.8 mL (P < .001), and global longitudinal strain from -10.5 ± 3.2 to -11.5 ± 3.0 (P = .01).

CRT programming to optimal CRI significantly improves LV systolic function, end-systolic volume, end-diastolic volume, and global longitudinal strain in nonresponders and incomplete responders to LBBAP, offering a non-invasive, practical clinical approach to improving response in patients having LBBAP.