Prognostic Implications of Heart Rate Score and Its Temporal Change in Left Ventricular Systolic Dysfunction: Insights From the HINODE Study.

Background: Heart rate score (HrSc) ≥ 70% reflects chronotropic incompetence and predicts prognosis in patients with cardiac implantable electronic devices (CIEDs) and left ventricular (LV) systolic dysfunction. However, its prognostic value in Japanese patients remains underexplored, and longitudinal changes in HrSc and their contributing factors are poorly characterized. Methods: This post hoc analysis of the Heart Failure Indication and Sudden Cardiac Death Prevention Trial in Japan (HINODE) included 172 patients with CIEDs and LV ejection fraction ≤ 50%. HrSc, defined as the percentage of all atrial-paced and sensed beats in a single tallest 10 beat/min device histogram bin, was assessed using remote monitoring. Results: At baseline, the median HrSc was 53% (interquartile range, 41%-83%), with 68 (39.5%) patients having HrSc ≥ 70%. During the 2-year follow-up, the incidence of all-cause death or heart failure (HF) events was similar between patients with HrSc ≥ 70% and < 70% (31.1% vs. 29.4%, log-rank Conclusion: In the HINODE study, baseline HrSc ≥ 70% was not predictive of 2-year cardiovascular outcomes. However, HrSc changed in approximately one-quarter of patients and was associated with clinical and device-related factors, as well as HF events. HrSc is not a static measure but a dynamic marker that reflects evolving patient conditions and CIED programming.