Does the Hurst exponent of heartbeat intervals change differently during physical activity in healthy subjects compared to those with stable angina pectoris?
The Hurst exponent of heartbeat intervals during exercise may serve as a useful new diagnostic parameter for short heartbeat time series to differentiate healthy individuals from those with stable angina pectoris.
The fractal scaling properties of the heartbeat time series are studied in different controlled ergometric regimes using both the improved Hurst rescaled range (R/S) analysis and the detrended fluctuation analysis (DFA). The long-time "memory effect" quantified by the value of the Hurst exponent H>0.5 is found to increase during progressive physical activity in healthy subjects, in contrast to those having stable angina pectoris, where it decreases. The results are also supported by the detrended fluctuation analysis. We argue that this finding may be used as a useful new diagnostic parameter for short heartbeat time series.
Martinis et al. (Wed,) studied this question.
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