Circadian, Circaheptan and Circannual Rhythms in Acute Myocardial Infarction

Circadian rhythm may have a significant role on the development of cardiovascular diseases such as acute myocardial infarction (AMI) and transient myocardial ischaemia. In addition, circaheptan and circannual rhythms in cardiovascular diseases have been recognized for some. With this purpose we studied 374 cases with AMI admitted to a coronary care unit in whom the time of onset of typical chest pain was not obscure. There was a significant morning peak between 6 a.m-noon in AMI. There was no significant difference in the distribution of cases by months, seasons and days of the week (p>0.05). Yet a circadian variation with a morning peak was observed for the onset of AMI. Possible triggers of onset of AMI were reviewed.