The circadian rhythm of angina pectoris.

Analysis of diary card data from 33,999 angina attacks recorded in 1,022 patients with chronic stable angina showed a clear circadian pattern to the frequency of angina that resembles patterns previously described for myocardial infarction and sudden cardiac death, with a peak in the morning. The majority of angina attacks were preceded by physical exertion and the circadian pattern was more pronounced for exertional angina than nonexertional angina. In this study, treatment with beta-blockers did not prevent the morning peak of angina attacks.