Effect of ectopic beats on heart rate variability indices in heart failure patients

Abstract

Heart rate variability (HRV) provides a valuable tool for early detection of cardiovascular abnormalities. Ectopic beats have been proven to have an influence on HRV results, but the effect of different amount of ectopic beats on analysis of congestive heart failure (CHF) patient rhythms has not been quantified. In this study, we tested the commonly used HRV indices for significant differences between 5-min RR segments with and without ectopic beats. Eight long-term CHF RR interval recordings from http://www.physionet.org were studied. Each recording was divided into non-overlapping segments of 5-min RR segments without or with different numbers of ectopic beats. Two time-domain HRV indices of SDNN and RMSSD and two frequency-domain indices of normalized low frequency (LFn) and high frequency (HFn) powers were employed. Results showed that ectopic segments had significantly larger values for SDNN (39 ± 18 vs. ectopic free segments 28 ± 16 ms, P < 0.05), RMSSD (47 ± 29 vs. 24 ± 23 ms, P < 0.05) and HFn (0.66 ± 0.13 vs. 0.52 ± 0.14, P < 0.01), and significantly lower values for LFn (0.34 ± 0.13 vs. ectopic free segments 0.48 ± 0.14, P < 0.01). Compared with the indices of RMSSD and frequency-domain indices, SDNN was least affected by a relatively small amount of ectopic beats (one to six beats). Compared with the time-domain indices, the frequency-domain indices responded more quickly to the appearance of ectopic beats.