Heart rate variability profiles in symptomatic coronary artery disease and preserved left ventricular function: Relation to ventricular tachycardia and transient myocardial ischemia

We studied heart rate variability in ambulatory electrocardiographic recordings from 312 patients with significant coronary artery disease and a left ventricular ejection fraction of ≥30%. Only those patients who had both episodes of ischemia and nonsustained ventricular arrhythmias showed diminished values for parasympathetic nonspectral and spectral heart rate (HR) variability parameters. The root mean square of difference of successive R-R intervals (RMSSD) and high-frequency (HF) power in this group were 28 ± 3 msec and 9 ± 1 msec, respectively. The highest values of these HR variability parameters were found in patients with nonsustained ventricular tachycardia and no ischemia (81 ± 21 msec and 14 ± 1 msec, respectively, p ≤ 0.05). A relation was seen between transient myocardial ischemia and low-frequency power and between transient ischemia and ventricular tachycardia. These data suggest that the autonomic nervous system may play a role in ischemia and in ischemia-related ventricular arrhythmias.