749-5 Reduced Complexity of R-R Interval Dynamics in Patients with Coronary Artery Disease

Abstract

In order to assess the fractal characteristics of R-R interval dynamics and the applicability of fractal model in detecting abnormalities in heart period variability (HPV), fractal, spectral and time domain measures of HPV were compared between 40 patients with uncomplicated coronary artery disease (CAD) and 40 age-matched healthy subjects without evidence of heart disease. Fractal dimension (D) was calculated with an epsilon-blanket method and autoregressive model was used in spectral analysis of HPV. A good fit of the regression line and a stable D (correlation coefficients > 0.95) were observed from the time epochs varying from 100 to 4 000 consecutive R-R intervals. Patients with CAD had significantly lower 24-hour average D (1.66 ± 0.09) compared to healthy subjects (1.74 ± 0.05) (p < 0.001 between the groupsl, but none of the time or frequency domain measures of HPV, such as standard deviation of R-R intervals, high-frequency, low-frequency or very low-frequency power spectral components, differed significantly between the groups. R-R interval dynamics has fractal characteristics as evidenced by selfsimilarity of D over wide range of R-R interval time series. Patients with CAD have reduced dimensional complexity of R-R interval dynamics but no significant alterations in specific autonomic or other regulatory systems that modulate the periodic HRV.