title: Questing for circadian dependence in ST-segment-elevation acute myocardial infarction: a multicentric and multiethnic study.
abstract: BACKGROUND
  Four monocentric studies reported that circadian rhythms can affect left ventricular infarct size after ST-segment-elevation acute myocardial infarction (STEMI).
  
  
  OBJECTIVE
  To further validate the circadian dependence of infarct size after STEMI in a multicentric and multiethnic population.
  
  
  RESULTS
  We analyzed a prospective cohort of subjects with first STEMI from the First Acute Myocardial Infarction study that enrolled 1099 patients (ischemic time <6 hours) in Italy, Scotland, and China. We confirmed a circadian variation of STEMI incidence with an increased morning incidence (from 6:00 am till noon). We investigated the presence of circadian dependence of infarct size plotting the peak creatine kinase against time onset of ischemia. In addition, we studied the patients from the 3 countries separately, including 624 Italians; all patients were treated with percutaneous coronary intervention. We adopted several levels of analysis with different inclusion criteria consistent with previous studies. In all the analyses, we did not find a clear-cut circadian dependence of infarct size after STEMI.
  
  
  CONCLUSIONS
  Although the circadian dependence of infarct size supported by previous studies poses an intriguing hypothesis, we were unable to converge toward their conclusions in a multicentric and multiethnic setting. Parameters that vary as a function of latitude could potentially obscure the circadian variations observed in monocentric studies. We believe that, to assess whether circadian rhythms can affect the infarct size, future study design should not only include larger samples but also aim to untangle the molecular time-dynamic mechanisms underlying such a relation.
authors: San Raffaele Scientific Institute and Vita-Salute University, Milan, Italy. ammirati.enrico@hsr.it
authors: Enrico
authors: E
authors: Ammirati
authors: Nicole
authors: N
authors: Cristell
authors: Domenico
authors: D
authors: Cianflone
authors: Anna-Chiara
authors: AC
authors: Vermi
authors: Giancarlo
authors: G
authors: Marenzi
authors: Monica
authors: M
authors: De Metrio
authors: Neal G
authors: NG
authors: Uren
authors: Dayi
authors: D
authors: Hu
authors: Timothy
authors: T
authors: Ravasi
authors: Attilio
authors: A
authors: Maseri
authors: Carlo V
authors: CV
authors: Cannistraci
keywords: acute myocardial infarction; circadian rhythm; myocardial injury; systems biology; time onset of myocardial infarction