Relationship between entropy and symbolic analysis indices of heart rate variability in patients with coronary artery disease with and without diabetes mellitus

The aim of this study was to evaluate the relationship between Shannon entropy (SE) and symbolic analysis (SA) of heart rate variability at rest in 3 groups: patients with coronary artery disease (CAD), CAD with diabetes mellitus (CAD-DM), and healthy individuals (H). We evaluated 44 men into the groups (CAD, n=16, CAD-DM, n=13 and H, n=15). The R-R intervals (R-Ri) were recorded at rest in the supine position for 15 minutes. SA analysis classified patterns of R-Ri according to the number of variations into stable and unstable patterns. Significant and negative correlation was found between SE and the percentage of stable patterns for CAD and CAD-DM. Positive correlation was found between SE and the percentage of unstable patterns in all the groups. We conclude that complexity of cardiovascular control had a positive relationship with the cardiac parasympathetic modulation in all groups and negative relationship with the sympathetic modulation in CAD and CAD-DM groups.