Time sequence of anginal pain.

We studied 187 patients with angina at rest in order to evaluate the circadian rhythm of chest pain attacks. All subjects were followed for 7 days in absence of therapy (placebo period) and then with therapy (nifedipine, metoprolol, or isosorbide dinitrate). During the placebo period (1309 days) 1466 attacks were recorded, on an average of 1.1 per day. Most episodes occurred between 5 and 8 A.M. The incidence of chest pain attacks was much lower between 9 A.M. and 4 P.M. During the period with therapy, a reduction of painful episodes was observed, while the diurnal distribution remained unchanged. Furthermore, we studied the relationship between circadian distribution of anginal attacks and the extension of coronary damage in the 76 patients who underwent coronary angiography. Alterations of diurnal distribution of chest pain attacks were noted in subjects with normal coronary arteries and those with one-vessel and two-vessel disease. Patients with three-vessel disease or left main coronary artery stenosis showed more uniform distribution of their attacks.