Circadian distribution of ischemic attacks and ischemia-related ventricular arrhythmias in patients with variant angina

BACKGROUND: There are limited data about the circadian distribution of ischemic episodes in patients with variant angina. Furthermore, no previous study investigated whether ischemia-related ventricular arrhythmias follow a circadian variation in these patients. METHODS: The circadian variation of transient ischemia and ischemia-induced ventricular arrhythmias was assessed by cosinor methodology on 24-hour Holter recordings of 26 patients with variant angina. RESULTS: On the whole, 301 ischemic episodes were detected in the population, with premature ventricular complexes occurring in 49 of them (16%). Ischemic episodes followed a typical circadian variation (acrophase hr 02:36, p < 0.01) in the total sample. However, a significant circadian variation of ischemic episodes was detectable in the 14 patients without (n = 167, acrophase hr 04:00, p < 0.0001), but not in the 12 patients with (n = 134, p = 0.14) hemodynamically significant coronary stenoses, independently of the location (anterior/inferior) of ischemia. There was no significant circadian variation of ischemia-related ventricular arrhythmias. CONCLUSIONS: Among patients with variant angina, a clearcut circadian variation of ischemia is present in those without, but not in those with, hemodynamically significant coronary artery stenoses, thus suggesting that different pathophysiologic mechanisms may operate, at least in part, in triggering coronary spasm in these two subgroups of patients. There was no significant circadian variation of ischemia-related ventricular arrhythmias in these patients.