title: Circadian rhythm of angina in patients with unstable angina: relationship with extent of coronary disease, coronary reserve and ECG changes during pain.
abstract: A circadian distribution of ischaemic events has been identified in ambulatory patients with stable angina. However, whether a similar distribution occurs in patients with unstable angina who remain at bed rest is still uncertain. Therefore, we analysed the possible circadian presentation of episodes of angina at rest (n = 1222) in 193 patients hospitalized consecutively. The influence of extent of coronary disease (number of vessels with > 70% stenosis, 0, 1 and 2-3), type of ECG changes during pain on a 12-lead ECG, and coronary reserve, as assessed by ischaemic threshold (atrial pacing), were also evaluated. There were two peaks of highest incidence: at 0700-1000h and at 1900-2200h (P < 0.0001) which were unrelated to the extent of coronary disease, coronary reserve or type of ECG change. Patients with 1 or 2-3 vessel disease with a reduced ischaemic threshold (= < 150 beats.min-1), however, had a higher incidence of midnight angina (2300-0200h) than those with a normal threshold or with no vessel disease (P < 0.001). It is concluded that, in spite of being at bed rest, patients with unstable angina present a definite circadian distribution of angina, with peaks in the early morning and late evening. Patients with a low coronary reserve seem to have a higher incidence of midnight angina than others.
authors.affiliation: Unitat Coronaria, Hospital General Vall d'Hebrón, Barcelona, Spain.
authors.forename: J
authors.initials: J
authors.lastname: Figueras
authors.forename: R M
authors.initials: RM
authors.lastname: Lidón
mesh_terms: D000789:Angina, Unstable / Q000175:diagnosis / Q000503:physiopathology*; D001510:Bed Rest; D002304:Cardiac Pacing, Artificial; D002940:Circadian Rhythm / Q000502:physiology*; D017023:Coronary Angiography; D003326:Coronary Circulation / Q000502:physiology; D004562:Electrocardiography; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000175:diagnosis / Q000503:physiopathology