Heart Rate Dynamics in Patients With Stable Angina Pectoris and Utility of Fractal and Complexity Measures

Dynamic analysis techniques may uncover abnormalities in heart rate (HR) behavior that are not easily detectable with conventional statistical measures. However, the applicability of these new methods for detecting possible abnormalities in HR behavior in various cardiovascular disorders is not well established. Conventional measures of HR variability were compared with short-term (≤11 beats, α 1) and long-term (>11 beats, α 2) fractal correlation properties and with approximate entropy of RR interval data in 38 patients with stable angina pectoris without previous myocardial infarction or cardiac medication at the time of the study and 38 age-matched healthy controls. The short- and long-term fractal scaling exponents (α 1, α 2) were significantly higher in the coronary patients than in the healthy controls (1.34 ± 0.15 vs 1.11 ± 0.12 [p