title: Circadian variation of acute myocardial infarction in young people.
abstract: OBJECTIVE
  The aim was to investigate the circadian and weekly variation in Chinese young patients with acute myocardial infarction (AMI).
  
  
  METHODS
  This was a 10-year retrospective cohort study. We studied patients (>18 to <45 years of age) with a first attack of AMI from the emergency departments of 3 university teaching hospitals in Taiwan from January 1, 2001, to December 31, 2010. We analyzed patients in the standard circadian fashion using 6-hour intervals (00:01-06:00, 06:01-12:00, 12:01-18:00, and 18:01-24:00). We also did an analysis by day of week.
  
  
  RESULTS
  The database had 505 patients with AMI with complete data. The percentage of total AMIs that occurred in the 6-hour intervals were as follows: 00:01 to 06:00, 30.9%; 06:01 to 12:00, 23.4%; 12:01 to 18:00, 25.9%; and 18:01 to 24:00, 19.8%. The percentage of AMIs between 00:01 and 06:00 was significant higher compared with that in the other three 6-hour intervals (df = 3, χ(2) = 91.7, P < .001). However, there was no significant weekly variation for these patients in the present study.
  
  
  CONCLUSIONS
  There was a significant circadian variation with a peak from 00:01 to 06:00 in Chinese young patients with AMI. However, there was no significant weekly variation in these patients. The circadian periodicity may create new possibilities for disease prevention and medication prescription.
authors.affiliation: Department of Emergency Medicine, Cathay General Hospital, Taipei 106, Taiwan.
authors.forename: Chia-Meng
authors.initials: CM
authors.lastname: Chan
authors.forename: Wei-Lung
authors.initials: WL
authors.lastname: Chen
authors.forename: Hung-Yi
authors.initials: HY
authors.lastname: Kuo
authors.forename: Chien-Cheng
authors.initials: CC
authors.lastname: Huang
authors.forename: Ying-Sheng
authors.initials: YS
authors.lastname: Shen
authors.forename: Cheuk-Sing
authors.initials: CS
authors.lastname: Choy
authors.forename: Jiann-Hwa
authors.initials: JH
authors.lastname: Chen
mesh_terms: D000328:Adult; D016009:Chi-Square Distribution; D002940:Circadian Rhythm; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D008297:Male; D009203:Myocardial Infarction / Q000453:epidemiology*; D012189:Retrospective Studies; D012307:Risk Factors; D013624:Taiwan / Q000453:epidemiology; D055815:Young Adult