We show the MSE analysis (Fig. 3) of RR interval time series using i) the mean and ii) the mean absolute deviation ( ) metrics for coarsegraining the time series. The parameter r is fixed at 8 ms. (The mean absolute difference is another measure of local variability.) The results indicate that healthy young subjects have the highest dynamical complexity, when considering both fluctuations in the mean and the mean absolute deviation (dispersion). The degrees of separation among the groups obtained with MSE_{μ} and MSE_{MAD} are qualitatively comparable. (The area under the curve (AUC) of younger versus older is 0.85 and 0.88 for MSE_{μ} and MSE_{MAD}, respectively. The AUC of healthy older individual versus patients with CHF is 0.85 and 0.90 for MSE_{μ} and MSE_{MAD}, respectively.

Madalena Costa (mcosta3@bidmc.harvard.edu)