title: High-sensitivity troponin T for early rule-out of myocardial infarction in recent onset chest pain.
abstract: OBJECTIVE
  To investigate whether a high-sensitivity troponin assay, shown to improve early detection of acute myocardial infarction (AMI), permits accelerated rule-in/rule-out of AMI.
  
  
  METHODS
  Patients who presented to the emergency department within 4 h of the onset of chest pain suggestive of acute coronary syndrome were prospectively recruited from November 2007 to April 2010. Blood samples were taken at 0, 1, 2 and 12-24 h after presentation and were analysed for clinically applied troponin I and for high-sensitivity troponin T (hsTnT). The dynamic change in hsTnT levels between time points was measured. The primary outcome was admission diagnosis of AMI.
  
  
  RESULTS
  Of the 385 patients recruited, 82 (21.3%) had AMI. The sensitivity of hsTnT by 2 h was 95.1% (88.7-98.1%), specificity 75.6% (73.8-76.5%), positive predictive value 53.8% (50.2-55.5%) and negative predictive value 98.3% (96.0-99.3%). The sensitivity was not statistically different between peak values at 2 h and 24 h. Adding ECG results reduced the false negative rate to 1.2%. The additional application of ≥20% delta criterion over the 2 h period for 0-2 h samples increased specificity to 92.4% (90.2-94.3%) but reduced sensitivity to 56.1% (48.0-63.2%).
  
  
  CONCLUSIONS
  hsTnT taken at 0 and 2 h after presentation, together with ECG results, could identify patients suitable for early stress testing with a false negative rate for AMI of 1.2%. Further trials of such an approach are warranted. The specificity of hsTnT for diagnosing AMI could be improved by the use of a delta of ≥20%, but at the cost of major reductions in sensitivity.
authors: Christchurch Hospital, Cardiology Department, New Zealand. sally.aldous@cdhb.govt.nz
authors: Sally
authors: S
authors: Aldous
authors: Chris
authors: C
authors: Pemberton
authors: A Mark
authors: AM
authors: Richards
authors: Richard
authors: R
authors: Troughton
authors: Martin
authors: M
authors: Than
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000097:blood; D002637:Chest Pain / Q000097:blood*; D016009:Chi-Square Distribution; D004562:Electrocardiography; D004636:Emergency Service, Hospital; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000175:diagnosis*; D009520:New Zealand; D011446:Prospective Studies; D012372:ROC Curve; D012680:Sensitivity and Specificity; D018709:Statistics, Nonparametric; D019210:Troponin I / Q000097:blood; D020107:Troponin T / Q000097:blood*
chemical_list: D015415:Biomarkers; D019210:Troponin I; D020107:Troponin T