Abstract 13515: Continuous Optimization of Atrioventricular Pacing Timing of Cardiac Resynchronization Therapy in Heart Failure Patients With Pacemaker Dependency

Background: BLOCK HF study demonstrated that biventricular pacing was superior to conventional right ventricular pacing in heart failure (HF) patients with atrioventricular (AV) block. An adaptive cardiac resynchronization therapy algorithm (aCRT) provides continuous pacing timings of AV delays based on periodic automatic evaluation of electrical conduction even in the patients with AV block, and is effective in patients with CRT devices. However, it is uncertain whether this algorithm has better benefits even in patients with pacemaker dependency.

Methods: Between Jan/2016-Dec/2022, a total of 359 patients were implanted CRT devices. Pacemaker-dependent CRT patients with aCRT algorithm function were selected from them. Sixty-five patients with pacemaker dependency (31 patients using the aCRT algorithm [adaptive group] and 34 patients not using the aCRT algorithm [non-adaptive group]) were included in the analysis. Pacemaker dependency was defined as absence of spontaneous ventricular activity during sensing test at VVI 30 bpm or long atrioventricular delay (>300ms). The primary endpoint was a composite clinical outcome of all cause death and/or HF hospitalization.

Results: There were no significant differences in baseline characteristics between two groups. During a median follow-up of 1,067 days (interquartile range 553-1,776 days), the aCRT reduced the risk of the composite clinical outcome in patients with pacemaker dependency (log-rank P=0.0187, Figure). In addition, use of the aCRT algorithm was an independent predictor of the composite clinical outcomes in the multivariate analysis (hazard ratio 0.32, 95% confidence interval: 0.12-0.88, P=0.028).

Conclusions: The aCRT algorithm was useful and significantly reduced the risk of the clinical outcome, even in patients with pacemaker dependency.