Effects of Ivabradine on Patients with Depressed Left Ventricular Function after Cardiac Resynchronization Therapy.

Background: The potential synergistic effect of ivabradine and cardiac resynchronization therapy (CRT) in heart failure (HF) patients has rarely been studied. We aimed to evaluate the clinical benefits of ivabradine in patients with left ventricular dysfunction following CRT implantation. Methods: Two hundred and thirty-one patients receiving CRT were consecutively enrolled between January 2014 and December 2018 from two HF centers. A total of 123 patients had left ventricular ejection fraction (LVEF) < 40% and resting sinus heart rate (HR) ≥ 75 bpm after six months of CRT implantation. Among these patients, 45 were treated with ivabradine (Group 1), and 78 did not receive ivabradine treatment (Group 2). Results: Baseline characteristics and prescription rates of HF medications other than ivabradine were similar between the two groups. In Group 1, the mean HR decreased from 82.2 ± 11.4 bpm to 76.3 ± 10.5 bpm (p = 0.012), and the mean LVEF increased from 29.9 ± 6.5% to 38.8 ± 12.4% (p < 0.001). Atrial pacing percentage, biventricular pacing percentage, and burden of atrial fibrillation (AF) were not significantly different between the two groups during the study period. The patients' daily physical activity increased significantly in Group 1 compared to Group 2 (Δ daily activity 0.4 ± 0.7 hours/day vs. -0.1 ± 7.2 hours/day, p < 0.001). Conclusions: Ivabradine could effectively reduce HR and improve physical activity. It was safe to use and did not increase AF burden or affect biventricular pacing percentage in CRT recipients.