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: < .05). Receiver operating characteristic analysis showed that the SNS index at a 9-minute ECG interval had the highest area under the curve, followed by the triangular index at a 2-minute ECG interval for the recovered EF group (0.724 and 0.718, respectively). 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.