Circadian and Seasonal Variations in the Frequency of Onset of Acute Myocardial Infarction

Kim, Bum Soo; Ho, Kang Jin; Seo, Won Tae; Lee, Man Ho; Park, Jung Ro

Abstract

BACKGROUND
The onset of acute myocardial infarctin varies in a circadian and seasonal pattern, with a morning and winter peak. The purpose of this study was to determine whether the frequency of onset of acute myocardial infarction varies circadianly and seasonally in Korean patients.
METHODS
We analyzed the time of onset of chest pain in 409 patients with myocardial infarction admitted to our hospital over the past 30 years according to a 24-hour and 12 month period.
RESULTS
There notel marked circadian variations in the frequency of onset, with the primary peak from 6 a.m. to noon and the secondary peak from 6 p.m. to midnight (p<0.001). Circadian bimodal rhythmicity of myocardial infarction was demonstrated in this study. By the sex analysis, circadian variations of frequency of acute myocardial infarction were also similar to those of total patients. Interestingly, circadian variations were slightly different in the patients below 50 years of age, showing the highest frequency of onset in the time between 6 pm and midnight (p<0.062). And we also analyzed the frequency of onset of AMI by seasons. The notel a peak incidence in autumn, and followed by winter and spring. But we didn't find any statistical significance (p<0.059). However, comparing summer to other seasons, summer showed the lowest incidence of myocardial infarction with statistical significance (p<0.001).
CONCLUSIONS
Ever though the study population in small, this study showed that the frequency of acute myocardial infarction had a circadian and a seasonal variation in Korean patients.