Reliability and accuracy of heart rate variability metrics versus ECG segment duration

Heart rate variability (HRV) has been used in many studies to assess the effects of autonomic regulation on the heart rate. A 1996 task force specified standards for calculating HRV metrics and reporting results. The standards focused on metrics calculated from short-term (5 min) and long-term (24 h) recordings of the electrocardiogram (ECG). We compared the accuracy of nine HRV metrics calculated from ECG records spanning 10 s to 10 min to that calculated from a 5 min record. We also estimated the reliability of all nine metrics calculated from 5 min records. We found that high frequency power (HF) and the root mean square of successive NN interval differences (RMSSD) were substantially less sensitive to the segment duration and more reliable than the other seven metrics.