title: Health outcomes categorized by current and previous definitions of acute myocardial infarction in an unselected cohort of troponin-naïve emergency department patients.
abstract: BACKGROUND
  In a population originally classified for acute myocardial infarction (AMI) by the World Health Organization (WHO) definition, we compared the health outcomes after retrospectively reclassifying with the European Society of Cardiology and the American College of Cardiology (ESC/ACC) AMI definition, using the peak cardiac troponin I (cTnI) concentrations. The health outcomes were based on the WHO definition and occurred in an era that preceded the use of cardiac troponin biomarkers.
  
  
  METHODS
  For 448 patients who presented to the emergency department with symptoms suggestive of cardiac ischemia in 1996, we obtained data for all-cause mortality and recurrent AMI for up to 1 year after the initial presentation. We performed retrospective analysis of the patients' frozen plasma samples to measure cTnI (AccuTnI, Beckman Coulter).
  
  
  RESULTS
  At 30, 120, and 360 days, the risk for AMI/death in patients positive for AMI by only the ESC/ACC criteria was significantly lower than the risk in patients positive by both ESC/ACC and WHO criteria, and significantly higher than in patients negative according to both criteria. In a separate analysis, patients with a peak cTnI>0.10 microg/L were at greater risk for AMI/death than patients with cTnI concentrations of 0.04-0.10 microg/L. Patients negative by both definitions or with peak cTnI concentrations<0.04 microg/L had the highest event-free survival rates (92% and 94%, respectively) at 1 year.
  
  
  CONCLUSIONS
  In a troponin-naïve population, patients classified as positive for AMI by only the ESC/ACC criteria have a prognosis that appears to be intermediate between those classified positive by both the WHO and ESC/ACC definitions and those who meet neither criteria.
authors.affiliation: Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON, Canada, and Department of Pathology, Women and Infants Hospital of Rhode Island, Providence, USA. kavsakp@mcmaster.ca
authors.forename: Peter A
authors.initials: PA
authors.lastname: Kavsak
authors.forename: Andrew R
authors.initials: AR
authors.lastname: MacRae
authors.forename: Glenn E
authors.initials: GE
authors.lastname: Palomaki
authors.forename: Alice M
authors.initials: AM
authors.lastname: Newman
authors.forename: Dennis T
authors.initials: DT
authors.lastname: Ko
authors.forename: Viliam
authors.initials: V
authors.lastname: Lustig
authors.forename: Jack V
authors.initials: JV
authors.lastname: Tu
authors.forename: Allan S
authors.initials: AS
authors.lastname: Jaffe
mesh_terms: D000368:Aged; D000572:American Heart Association; D015415:Biomarkers / Q000097:blood; D015331:Cohort Studies; D018572:Disease-Free Survival; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data*; D005060:Europe; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000097:blood / Q000145:classification* / Q000175:diagnosis*; D009864:Ontario; D017063:Outcome Assessment, Health Care; D017410:Practice Guidelines as Topic; D011379:Prognosis; D012189:Retrospective Studies; D018570:Risk Assessment; D019210:Troponin I / Q000097:blood*; D014944:World Health Organization
chemical_list: D015415:Biomarkers; D019210:Troponin I