Weekly Variation of Acute Myocardial Infarction Increased Monday Risk in the Working Population

Background Seasonal and circadian variations in the occur-rence 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 ana-lyzed 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<.01) with a peak on Monday, whereas patients with sudden cardiac death (n=2960) wer