[Circadian variations in the incidence of transient ischemic myocardial episodes during hospitalization for acute myocardial infarct].

The aim of this research was to evaluate the incidence and circadian variation of episodes of transient myocardial ischemia in the predischarge period after acute myocardial infarction (AMI). One hundred and ninety patients were selected in stable clinical condition, 83 with inferoposterior AMI, 61 with anterior AMI, 12 with lateral AMI (34 patients with non Q AMI). The patients with unstable clinical course during the first 48 hours after admission were excluded. All patients underwent dynamic electrocardiography (Pathfinder 3 Reynolds Medicals) between the tenth and the fifteenth day of the in-hospital phase. Sixteen/190 patients showed ECG changes due to transient myocardial ischemia, with a length higher than 60 sec and with an interval between episodes higher than 60 sec. Ten patients had ST depression, 6 patients had ST elevation. In total, the ischemic episodes were 25, silent 21 and symptomatic 4, with incidence from 1 to 4 during 24 hours, with a length from 1 to 17 min (mean 8 min); mean heart rate increased during ischemic episodes. Seventeen/25 ischemic episodes occurred between the twelfth and the twenty-fourth hours. A follow-up of 15 +/- 3 months was carried-out: 1 patient died after reinfarction, 1 patient died of non cardiac cause, 6 patients showed unstable angina (in 4 of them myocardial revascularization procedure was performed), 8 patients were asymptomatic; on the contrary, 32/174 patients without episodes of myocardial ischemia presented cardiac events, with lesser incidence than ischemic patients (p < 0.01). This retrospective analysis showed higher evidence of episodes due to transient myocardial ischemia during the afternoon and evening hours in the in-hospital phase after AMI.(ABSTRACT TRUNCATED AT 250 WORDS)