Circadian Periodicity of Ischemic Heart Disease A Systematic Review of the Literature

A circadian pattern of acute myocardial infarction with a peak in the early morning waking hours has been reported since the 1980s. A MEDLINE literature search to identify relevant reports published during the last 20 years and focused on circadian variation of acute myocardial infarction was performed. Out of 1001 studies, 32 studies evaluating 34 populations were considered. Ratio between events per hour during the morning and events per hour during the other intervals hours of the day was 1.56 (95% confidence interval, 1.48–1.65). Despite the optimization of interventional and medical therapy of AMI since the first reports of circadian patterns in AMI occurrence, it was found that such a pattern still exists and that AMI happens most frequently in the morning hours.