title: Delta troponin for the early diagnosis of AMI in emergency patients with chest pain.
abstract: OBJECTIVE
  In patients presenting to the Emergency Department (ED) with potential acute myocardial infarction (AMI), elevated cardiac troponin (cTn) levels are indicative of myocardial necrosis. We assessed the accuracy of 'delta cTn' at 2h or 6h compared to the cTn concentration above the 99th percentile reference value for AMI in a prospective study of adult patients presenting to ED with symptoms suggestive of possible acute coronary syndrome.
  
  
  METHODS
  Blood was sampled for cardiac troponin I (cTnI) on presentation, and at 2h and 6h following presentation using a sensitive assay (Beckman AccuTnI). All clinical endpoints were adjudicated by a cardiologist who was blinded to the 2h cTn assay result.
  
  
  RESULTS
  Of the 874 patients, 70 (8%) were diagnosed with an AMI during their index presentation. The area under the ROC curve for diagnosing AMI at 2h was 0.89 [95%CI, 0.84-0.95] for absolute delta cTn versus 0.79 [95%CI 0.73-0.85] for the relative change. Specificity and PPV at 2h were optimized using a delta cTnI ≥ 0.03 μg/L (95.8% [95%CI 94.1-97.0] and 61.4% [95%CI 50.9-70.9] respectively). Sensitivity and NPV for AMI were optimized using the 99th percentile with the addition of a delta of<0.03 μg/L (97.1% [95%CI 90.2-99.2] and 99.7% [95%CI 99-99.9] respectively).
  
  
  CONCLUSIONS
  An algorithm incorporating cTnI concentration and delta cTn values with a sensitive troponin assay allows accurate diagnosis of AMI within 2h from presentation and earlier rule-out of AMI in the majority of patients.
authors.affiliation: Department of Emergency Medicine, Royal Brisbane and Women's Hospital, Brisbane, Australia; School of Public Health, Queensland University of Technology, Brisbane, Australia; School of Medicine, University of Queensland, Brisbane, Australia. Electronic address: louise_cullen@health.qld.gov.au.
authors.forename: Louise
authors.initials: L
authors.lastname: Cullen
authors.forename: William A
authors.initials: WA
authors.lastname: Parsonage
authors.forename: Jaimi
authors.initials: J
authors.lastname: Greenslade
authors.forename: Arvin
authors.initials: A
authors.lastname: Lamanna
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Hammett
authors.forename: Martin
authors.initials: M
authors.lastname: Than
authors.forename: Jillian
authors.initials: J
authors.lastname: Tate
authors.forename: Lauren
authors.initials: L
authors.lastname: Kalinowski
authors.forename: Jacobus P J
authors.initials: JP
authors.lastname: Ungerer
authors.forename: Kevin
authors.initials: K
authors.lastname: Chu
authors.forename: Anthony
authors.initials: A
authors.lastname: Brown
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D002637:Chest Pain / Q000097:blood / Q000209:etiology; D042241:Early Diagnosis; D004630:Emergencies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000097:blood* / Q000150:complications / Q000175:diagnosis*; D011446:Prospective Studies; D019210:Troponin I / Q000097:blood*
chemical_list: D019210:Troponin I
keywords: Acute coronary syndrome; Chest pain; Emergency medicine; Troponin