The circadian rhythm of angina pectoris. Amlodipine Angina Studies Group.

A clear circadian rhythm exists for angina, with the frequency of attacks increasing during the mid-morning and mid-afternoon hours. This pattern is comparable to circadian rhythms previously reported for the incidence of myocardial infarction and sudden cardiac death. The frequency of angina attacks precipitated by physical exertion showed a more pronounced circadian pattern compared to non-exertional angina. Beta-adrenergic blocking agents did not abolish the circadian rhythm of total angina and exertional angina attacks.