title: Variation in the time and day of onset of myocardial infarction and sudden death.
abstract: OBJECTIVE
  To examine circadian and weekly variation in the onset of acute myocardial infarction and sudden cardiac death.
  
  
  METHODS
  A large population based coronary heart disease register, the ARCOS Study, which is collaborating in the WHO MONICA Project carried out in Auckland, New Zealand, 1983-90. There were 4983 patients aged 25-64 with definite myocardial infarction or coronary death. Main outcome measures--circadian and weekly variation in onset of symptoms of definite myocardial infarction and sudden cardiac death.
  
  
  RESULTS
  Surviving patients showed a circadian pattern with a single morning peak in symptom onset (30.0%) while sudden death patients exhibited an afternoon peak (32.5%) and a secondary morning peak (27.6%). Within these two subgroups the circadian pattern was analysed by various risk factors and medications. A weekly variation was found with an increased incidence of onset of symptoms during the weekend and on Monday for surviving patients and a Saturday high (18.6%) for sudden death patients.
  
  
  CONCLUSIONS
  Further investigation of physiological changes within subgroups during the key periods may provide insight into triggering mechanisms and lead to better means for prevention.
authors.affiliation: Department of Community Health, University of Auckland School of Medicine.
authors.forename: J
authors.initials: J
authors.lastname: van der Palen
authors.forename: C J
authors.initials: CJ
authors.lastname: Doggen
authors.forename: R
authors.initials: R
authors.lastname: Beaglehole
mesh_terms: D000328:Adult; D002940:Circadian Rhythm; D016757:Death, Sudden, Cardiac / Q000453:epidemiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000453:epidemiology / Q000503:physiopathology*; D009520:New Zealand / Q000453:epidemiology; D012042:Registries; D017741:Survivors