Effects of backward difference on DFA of RR interval data of CHF subjects

In this study, the detrended fluctuation analysis (DFA) is applied to examine characteristics of RR interval time series of subjects with congestive heart failure (CHF) and those of subjects with normal sinus rhythm (NSR). In addition to original RR interval time series, the differenced RR interval time series of both NSR and CHF subjects are obtained using the backward difference. From the computational results, it is shown that there is a significant difference between the scaling exponents of differenced RR interval time series of CHF subjects and those of NSR subjects. Such significant difference is however not obtained for the original RR interval time series. The computational results therefore suggest that the backward difference may be applied to enhance the classification of CHF using the DFA.