RESUMO
INTRODUCTION AND OBJECTIVES: The aim of this study was to analyze the influence of modifiable cardiovascular risk factors on the circadian rhythm of acute myocardial infarction. PATIENTS AND METHOD: We analyzed a retrospective cohort of 54,249 patients from a multicenter study of acute myocardial infarction (the Spanish ARIAM study). The variables were time of onset of symptoms, age, sex, previous ischemic heart disease, coronary unit discharge status, previous stroke, familial antecedents of ischemic heart disease, hypertension, diabetes, dyslipidemia, smoking, and reinfarction. To verify the presence of circadian rhythm, we developed a simple test of equality of time series based on cosinor analysis of multiple sinusoid curves. Three sinusoids (24, 12 and 8 hour periods) were used. RESULTS: The time of onset of pain showed a circadian rhythm (P< .01), with a peak at 10:07 am and a trough at 4:46 am. All subgroups categorized according to the presence of the variables analyzed here showed a circadian rhythm, with a sinusoid curve after adjustment. In patients with diabetes or reinfarction or who were smokers, the sinusoid curve was bimodal. CONCLUSIONS: Time of onset of symptoms in patients with acute myocardial infarction follows a circadian rhythm. Diabetes, smoking and reinfarction can modify the standard circadian rhythm of onset of myocardial infarction.
