title: Rapid exclusion of acute myocardial infarction in patients with undetectable troponin using a high-sensitivity assay.
abstract: OBJECTIVE
  This paper sought to evaluate whether high sensitivity troponin (hs-cTnT) can immediately exclude acute myocardial infarction (AMI) at a novel 'rule out' cut-off.
  
  
  BACKGROUND
  Subgroup analysis of recent evidence suggests that undetectable hs-cTnT may exclude AMI at presentation.
  
  
  METHODS
  In a cohort study, we prospectively enrolled patients with chest pain, evaluating them with standard troponin T and testing for hs-cTnT (Roche Diagnostics, Basel, Switzerland) at presentation. The primary outcome was a diagnosis of AMI. We also followed up patients for adverse events within 6 months. After subsequent clinical implementation of hs-cTnT, we again evaluated whether initially undetectable hs-cTnT ruled out a subsequent rise.
  
  
  RESULTS
  Of 703 patients in the cohort study, 130 (18.5%) had AMI, none of whom initially had undetectable hs-cTnT (sensitivity: 100.0%, 95% confidence interval [CI]: 95.1% to 100.0%, negative predictive value: 100.0%, 95% CI: 98.1% to 100.0%). This strategy would rule out AMI in 27.7% of patients, 2 (1.0%) of whom died or had AMI within 6 months (1 periprocedural AMI, 1 noncardiac death). We evaluated this approach in an additional 915 patients in clinical practice. Only 1 patient (0.6%) with initially undetectable hs-cTnT had subsequent elevation (to 17 ng/l), giving a sensitivity of 99.8% (95% CI: 99.1% to 100.0%) and a negative predictive value of 99.4% (95% CI: 96.6% to 100.0%).
  
  
  CONCLUSIONS
  Undetectable hs-cTnT at presentation has very high negative predictive value, which may be considered to rule out AMI, identifying patients at low risk of adverse events. Pending further validation, this strategy may reduce the need for serial testing and empirical treatment, enabling earlier reassurance for patients and fewer unnecessary evaluations and hospital admissions.
authors.affiliation: University of Manchester, Manchester, United Kingdom. richard.body@manchester.ac.uk
authors.forename: Richard
authors.initials: R
authors.lastname: Body
authors.forename: Simon
authors.initials: S
authors.lastname: Carley
authors.forename: Garry
authors.initials: G
authors.lastname: McDowell
authors.forename: Allan S
authors.initials: AS
authors.lastname: Jaffe
authors.forename: Michael
authors.initials: M
authors.lastname: France
authors.forename: Kennedy
authors.initials: K
authors.lastname: Cruickshank
authors.forename: Christopher
authors.initials: C
authors.lastname: Wibberley
authors.forename: Michelle
authors.initials: M
authors.lastname: Nuttall
authors.forename: Kevin
authors.initials: K
authors.lastname: Mackway-Jones
mesh_terms: D015415:Biomarkers / Q000097:blood; D003951:Diagnostic Errors; D003935:Diagnostic Techniques, Cardiovascular / Q000706:statistics & numerical data*; D042241:Early Diagnosis; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000097:blood / Q000175:diagnosis*; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012372:ROC Curve; D015203:Reproducibility of Results; D013997:Time Factors; D020107:Troponin T / Q000097:blood*
chemical_list: D015415:Biomarkers; D020107:Troponin T