Alterations of Autonomic Nervous Activity Associated with Spontaneous Coronary Spasm in Patients with Variant Angina

ABSTRACT

BACKGROUND AND OBJECTIVES: It is now well known that coronary artery spasm plays an important role in the pathogenesis of variant angina. Previous studies have shown that stimulation of the sympathetic or parasympathetic nervous system can provoke coronary artery spasms, although the precise causes of such spasms remain unclear. Power spectral analysis of heart rate variability has been proposed as a noninvasive parameter of autonomic nervous activity. To determine the possible role of the autonomic nervous system in the development of variant angina, we used spectral analysis of heart rate variability obtained from ambulatory Holter monitoring in patients with ST-elevation and chest pain to clarify the alterations of autonomic activity before angina. SUBJCETS AND METHODS: Cardiac autonomic nervous activities were evaluated from the power of the low-frequency and the high-frequency spectral components of heart rate variability obtained from Holter monitoring in a total of 18 episodes of 12 patients with variant angina. Samples during each 10-minute period from 60 minutes before to immediately before an anginal attack were analyzed by fast Fourier transformation. RESULTS: Significant organic coronary stenosis and multiple coronary spasms were detected by coronary angiography in two (20%) and four (40%) of the patients, respectively. The values of the power of the low-frequency component and the low-to-high frequency ratio were significantly greater during the 10-to 0-minute period than during the other 10-minute periods. CONCLUSION: Sympathovagal imbalance - or sympathetic activation without parasympathetic augmentation - enhanced in the 10-minute period before an anginal attack may play an important role in the genesis of coronary artery spasms in patients with variant angina.