Background: The syndrome of variant angina occurs in patients with a wide spectrum of coronary disease ranging from angiographically normal coronary arteries to severe three-vessel disease. Survival and choice of therapy for these patients are determined by the extent of underlying fixed coronary obstruction. We examined whether heart rate variability (HRV) due to reduced vagal outflow may correlate with the severity of coronary stenoses in such patients.
Methods: Fifteen men and 2 women with clinically unstable variant angina underwent 24-hour Holter monitoring from which low and high-frequency power, standard deviation of mean 24-hour RR interval, proportion of adjacent RR intervals that differed by more than 50 ms, and mean root square of differences between successive RR intervals were extracted by power spectral analysis. Coronary angiography was later performed to determine coronary pathology and verify variant angina. As controls we studied an age-matched control group of 8 subjects (5 men, 3 women) with no clinical and/or electrocardiographic evidence of coronary heart disease or spasm as shown by negative treadmill exercise and hyperventilation tests.
Results: All measured components of HRV were significantly lower in the 9 patients with severe coronary artery disease compared to the 8 patients with normal coronary arteries or < 40% stenosis. The two groups were otherwise similar in terms of age and clinical parameters.
Conclusions: These preliminary findings on a small but carefully selected group of patients with variant angina indicate that the analysis of HRV can select patients with severe disease for a more intensive approach. These findings require confirmation on a larger patient series.