Background and purpose: Previous reports of a circadian variation of angina pectoris were based primarily on selected patients of clinical studies. The present ESCVA Study (European Survey on Circadian Variation of Angina Pectoris) was designed to determine the timing of angina pectoris attacks in outpatients, the association of wake time and possible external triggers with angina attacks, and the influence of cardiac medication on the circadian pattern.
Patients and methods: Inclusion criteria were stable angina pectoris for at least 3 months, average frequency of two or more attacks per week, and treatment with on-demand nitrates. Standardized self-administered questionnaires were provided to all participating physicians to obtain medical information and to their patients to obtain prospective recordings of angina attacks during the 7 subsequent days.
Results: From January 1998 to March 1999, 1,333 patients (60% male, 65 +/- 10 years, 40% female, 68 +/- 10 years) were enrolled in 243 centers of six European countries and reported a total of 4,293 angina pectoris attacks (range 0-48 per patient). The occurrence of angina pectoris demonstrated a significant circadian variation (p < 0.001) with a primary morning peak from 09:00 to 12:00 o'clock (relative risk 2.9, 95% confidence interval 2.6-3.2, compared to other times of day) and a secondary afternoon peak from 15:00 to 18:00 o'clock (relative risk 1.5, 95% confidence interval 1.3-1.7). Of all angina attacks 50% occurred within the initial 6 h after awakening, and 74% were associated with possible external triggers such as physical activity or anger.
Conclusion: The study demonstrated a marked wake time-related circadian variation in the occurrence of angina pectoris attacks. To improve preventive strategies, type, dosage and particularly timing of cardiac medication appear of importance, as may be behavior modification.