title: Acute myocardial infarction in chest pain patients with nondiagnostic ECGs: serial CK-MB sampling in the emergency department. The Emergency Medicine Cardiac Research Group.
abstract: OBJECTIVE
  This study tested the hypothesis that serial creatine phosphokinase (CK)-MB sampling in the emergency department can identify acute myocardial infarction (AMI) in patients presenting to the ED with chest pain and nondiagnostic ECGs.
  
  
  METHODS
  Patients more than 30 years old who were evaluated initially in the ED and hospitalized for chest pain were studied. Serial CK-MB levels were analyzed prospectively using a rapid serum immunochemical assay for identification of AMI patients in the ED. Presenting ECGs showing new, greater than 1-mm ST elevation in two or more contiguous leads were considered diagnostic for AMI. All other ECGs were considered nondiagnostic ECGs. CK-MB levels were determined at ED presentation and hourly for three hours (total of four levels). Patients with at least one level of more than 7 ng/mL were considered to have a positive enzyme study. The in-hospital diagnosis of AMI was determined by the development of typical serial ECG changes or separate standard cardiac enzyme changes after admission.
  
  
  METHODS
  Eight tertiary-care medical center hospitals.
  
  
  RESULTS
  Of the 616 study patients, 108 (17.5%) were diagnosed in the hospital as AMI; 69 of these AMI patients (63.9%) had nondiagnostic ECGs in the ED. Of the patients with nondiagnostic ECGs, 55 (sensitivity, 79.7%) had a positive ED serial CK-MB enzyme study within three hours after presentation. Combining serial ED CK-MB assay results with diagnostic ECGs yielded an 88.4% sensitivity for AMI detection within three hours of ED presentation. The predictive value of a negative serial ED enzyme study for no AMI was 96.2% (specificity, 93.7%).
  
  
  CONCLUSIONS
  Serial CK-MB determination in the ED can help identify AMI patients with initial nondiagnostic ECGs. Use of serial CK-MB analysis may facilitate optimal in-hospital disposition and help guide therapeutic interventions in patients with suspected AMI despite a nondiagnostic ECG.
authors.affiliation: University of Cincinnati Medical Center.
authors.forename: W B
authors.initials: WB
authors.lastname: Gibler
authors.forename: G P
authors.initials: GP
authors.lastname: Young
authors.forename: J R
authors.initials: JR
authors.lastname: Hedges
authors.forename: L M
authors.initials: LM
authors.lastname: Lewis
authors.forename: M S
authors.initials: MS
authors.lastname: Smith
authors.forename: S C
authors.initials: SC
authors.lastname: Carleton
authors.forename: R V
authors.initials: RV
authors.lastname: Aghababian
authors.forename: R O
authors.initials: RO
authors.lastname: Jorden
authors.forename: E J
authors.initials: EJ
authors.lastname: Allison
authors.forename: E J
authors.initials: EJ
authors.lastname: Otten
mesh_terms: D000328:Adult; D002637:Chest Pain / Q000209:etiology*; D003402:Creatine Kinase / Q000097:blood*; D004562:Electrocardiography; D005260:Female; D006801:Humans; D007527:Isoenzymes; D008297:Male; D009203:Myocardial Infarction / Q000175:diagnosis* / Q000201:enzymology; D011237:Predictive Value of Tests; D012372:ROC Curve; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D007527:Isoenzymes; D003402:Creatine Kinase