Weekly variation of acute myocardial infarction: Increased Monday risk in the working population

Abstract

Background: Seasonal and circadian variations in the occurrence of myocardial infarction and sudden cardiac death have been documented, suggesting that triggering factors may play a role in the causation of cardiac events. However, there are only sparse and conflicting data on the weekly distribution of the disorders. Methods and Results: To determine the weekly variation of acute myocardial infarction and sudden cardiac death, 5596 consecutive patients (71% men; age, 63±1 years) were analyzed in a regionally defined population (n=330 000; age, 25 to 74 years) monitored from 1985 to 1990. The exact time of onset of symptoms was used to determine the day of the event. Patients with myocardial infarction (n=2636) demonstrated a significant weekly variation (P