title: Is it possible to exclude a diagnosis of myocardial damage within six hours of admission to an emergency department? Diagnostic cohort study.
abstract: OBJECTIVE
  To assess the clinical efficacy and accuracy of an emergency department based six hour rule-out protocol for myocardial damage.
  
  
  METHODS
  Diagnostic cohort study.
  
  
  METHODS
  Emergency department of an inner city university hospital.
  
  
  METHODS
  383 consecutive patients aged over 25 years with chest pain of less than 12 hours' duration who were at low to moderate risk of acute myocardial infarction.
  
  
  METHODS
  Serial measurements of creatine kinase MB mass and continuous ST segment monitoring for six hours with 12 leads.
  
  
  METHODS
  Performance of the diagnostic test against a gold standard consisting of either a 48 hour measurement of troponin T concentration or screening for myocardial infarction according to the World Health Organization's criteria.
  
  
  RESULTS
  Outcome of the gold standard test was available for 292 patients. On the diagnostic test for the protocol, 53 patients had positive results and 239 patients had negative results. There were 18 false positive results and one false negative result. Sensitivity was 97.2% (95% confidence interval 95.0% to 99.0%), specificity 93.0% (90.0% to 96.0%), the negative predictive value 99.6%, and the positive predictive value 66.0%. The positive likelihood ratio was 13.9 and the negative likelihood ratio 0.03.
  
  
  CONCLUSIONS
  The six hour rule-out protocol for myocardial infarction is accurate and efficacious. It can be used in patients presenting to emergency departments with chest pain indicating a low to moderate risk of myocardial infarction.
authors.affiliation: Department of Emergency Medicine, Manchester Royal Infirmary, Manchester M13 9WL.
authors.forename: K R
authors.initials: KR
authors.lastname: Herren
authors.forename: K
authors.initials: K
authors.lastname: Mackway-Jones
authors.forename: C R
authors.initials: CR
authors.lastname: Richards
authors.forename: C J
authors.initials: CJ
authors.lastname: Seneviratne
authors.forename: M W
authors.initials: MW
authors.lastname: France
authors.forename: L
authors.initials: L
authors.lastname: Cotter
mesh_terms: D000328:Adult; D002985:Clinical Protocols; D015331:Cohort Studies; D003402:Creatine Kinase / Q000032:analysis*; D052279:Creatine Kinase, MB Form; D003937:Diagnosis, Differential; D004562:Electrocardiography; D006801:Humans; D007527:Isoenzymes / Q000032:analysis*; D008991:Monitoring, Physiologic / Q000379:methods*; D009203:Myocardial Infarction / Q000201:enzymology / Q000473:pathology*; D009206:Myocardium / Q000473:pathology*; D012306:Risk; D012680:Sensitivity and Specificity; D013997:Time Factors
chemical_list: D007527:Isoenzymes; D003402:Creatine Kinase; D052279:Creatine Kinase, MB Form