CARDIAC AUTONOMIC FUNCTION AND INCIDENT CORONARY HEART-DISEASE - A POPULATION-BASED CASE-COHORT STUDY - THE ARIC STUDY

Cardiac autonomic activity, as assessed by heart rate variability, has been found to be associated with postmyocardial infarction mortality, sudden death, and all-cause mortality. However, the association of he art rate variability and the incidence of coronary heart disease (CHD) is not well described. The authors report on the association of basel ine cardiac autonomic activity (1987-1989) with incident CHD after 3 y ears (1990-1992) of follow-up of the Atherosclerosis Risk in Communiti es Study cohort selected from four study centers in the United States by using a case-cohort design, The authors examined 137 incident cases of CHD and a stratified random sample of 2,252 examinees free of CHD at baseline. Baseline, supine, resting beat-to-beat heart rate data we re collected. High-(0.16-0.35 Hz) and low-(0.025-0.15 Hz) frequency sp ectral powers and high-now-frequency power ratio, estimated from spect ral analysis, and standard deviation of all normal R-R intervals, calc ulated from time domain analysis, were used as the conventional indice s of cardiac parasympathetic, sympatho-parasympathetic, and their bala nce, respectively. Incident CHD was defined as hospitalized myocardial infarction, fatal CHD, or cardiac revascularization procedures during 3 years of follow-up. The age, race, gender, and other CHD risk facto r-adjusted relative risks (and 95% confidence intervals) of incident C HD comparing the lowest quartile with the upper three quartiles of hig h-frequency power, low-frequency power, high-/low-frequency power rati o, and standard deviation of R-R intervals were 1.72 (95% confidence i nterval (Cl) 1.17-2.51), 1.09 (95% Cl 0.72-1.64), 1.25 (95% Cl 0.84-1. 86), and 1.39 (95% Cl 0.94-2.04), respectively. The findings from this population-based, prospective study suggest that altered cardiac auto nomic activity, especially lower parasympathetic activity, is associat ed with the risk of developing CHD.