Utility of short-term heart rate variability metrics in heart failure with reduced ejection fraction.

Background: Recently, reduced sympathetic nervous system (SNS) activity measured by 10-minute electrocardiogram (ECG)-based heart rate (HR) variability (HRV) was associated with heart failure (HF) with recovered ejection fraction (EF) (HFrecEF). However, there are no studies on the optimal ECG recording time to indicate HFrecEF in short-term HRV. Objective: In this study, the optimal ECG intervals and time-domain metrics to elucidate indicators for HFrecEF were investigated in HF with reduced EF (HFrEF). Methods: HRV analyses based on 2-, 4.5-, and 9-minute ECG intervals were performed in 4 groups: patients with persistent HFrEF (n = 40), HFrecEF (n = 41), and stage A HF (n = 73) and healthy controls (n = 40). Results: Mean HR and triangular and SNS indexes were significantly different across all of the 2-, 4.5-, and 9-minute ECG intervals among the 4 groups. In the logistic regression analysis adjusted for age, gender, body mass index, and mean HR, only the triangular index was significantly associated with recovery across all time intervals, whereas the SNS index at 2- and 9-minute ECG intervals was associated with recovery in EF (all Conclusion: In this study, a higher 2-minute triangular index and a lower 9-minute SNS index indicated functional EF recovery in HFrEF. Further prospective studies are needed to confirm the utility of short-term indexes to predict myocardial recovery after HF treatment.