title: The utility of presentation and 4-hour high sensitivity troponin I to rule-out acute myocardial infarction in the emergency department.
abstract: OBJECTIVE
  International guidance recommends that early serial sampling of high sensitivity troponin be used to accurately identify acute myocardial infarction (AMI) in chest pain patients. The background evidence for this approach is limited. We evaluated whether on presentation and 4-hour high-sensitivity troponin I (hs-cTnI) could be used to accurately rule-out AMI.
  
  
  METHODS
  hs-cTnI was measured on presentation and at 4-hours in adult patients attending an emergency department with possible acute coronary syndrome. We determined the sensitivity for AMI for at least one hs-cTnI above the 99th percentile for a healthy population or alone or in combination with new ischemic ECG changes. Both overall and sex-specific 99th percentiles were assessed. Patients with negative tests were designated low-risk.
  
  
  RESULTS
  63 (17.1%) of 368 patients had AMI. The median (interquartile range) time from symptom onset to first blood sampling was 4.8h (2.8-8.6). The sensitivity of the presentation and 4h hs-cTnI using the overall 99th percentile was 92.1% (95% CI 82.4% to 97.4%) and negative predictive value 95.4% (92.3% to 97.4%) with 78.3% low-risk. Applying the sex-specific 99th percentile did not change the sensitivity. The addition of ECG did not change the sensitivity.
  
  
  CONCLUSIONS
  Hs-cTnI >99th percentile thresholds measured on presentation and at 4-hours was not a safe strategy to rule-out AMI in this clinical setting irrespective of whether sex-specific 99th percentiles were used, or whether hs-cTnI was combined with ECG results.
authors.affiliation: Emergency Department, Christchurch Hospital, Christchurch, New Zealand; University of Otago, Christchurch, New Zealand.
authors.forename: John W
authors.initials: JW
authors.lastname: Pickering
authors.affiliation: Lipid and Diabetes Research Group, Christchurch, New Zealand.
authors.forename: Joanna M
authors.initials: JM
authors.lastname: Young
authors.affiliation: Canterbury Health Laboratories, Christchurch, New Zealand; University of Otago, Christchurch, New Zealand.
authors.forename: Peter
authors.initials: P
authors.lastname: George
authors.affiliation: Cardiology Department, Christchurch Hospital, Christchurch, New Zealand.
authors.forename: Sally
authors.initials: S
authors.lastname: Aldous
authors.affiliation: Department of Emergency Medicine, Royal Brisbane and Women's Hospital, Brisbane, Australia; School of Medicine, The University of Queensland, Brisbane, Australia; School of Public Health, The Queensland University of Technology, Brisbane, Australia.
authors.forename: Louise
authors.initials: L
authors.lastname: Cullen
authors.affiliation: Department of Emergency Medicine, Royal Brisbane and Women's Hospital, Brisbane, Australia; School of Medicine, The University of Queensland, Brisbane, Australia; School of Public Health, The Queensland University of Technology, Brisbane, Australia.
authors.forename: Jaimi H
authors.initials: JH
authors.lastname: Greenslade
authors.affiliation: University of Otago, Christchurch, New Zealand.
authors.forename: A Mark
authors.initials: AM
authors.lastname: Richards
authors.affiliation: University of Otago, Christchurch, New Zealand; Cardiology Department, Christchurch Hospital, Christchurch, New Zealand.
authors.forename: Richard
authors.initials: R
authors.lastname: Troughton
authors.affiliation: Emergency Department, Christchurch Hospital, Christchurch, New Zealand; University of Otago, Christchurch, New Zealand.
authors.forename: Michael
authors.initials: M
authors.lastname: Ardagh
authors.affiliation: University of Otago, Christchurch, New Zealand.
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Frampton
authors.affiliation: Emergency Department, Christchurch Hospital, Christchurch, New Zealand. Electronic address: martin.than@xtra.co.nz.
authors.forename: Martin P
authors.initials: MP
authors.lastname: Than
mesh_terms: D054058:Acute Coronary Syndrome / Q000097:blood / Q000175:diagnosis* / Q000503:physiopathology; D000368:Aged; D015415:Biomarkers / Q000097:blood; D002637:Chest Pain / Q000097:blood / Q000175:diagnosis* / Q000503:physiopathology; D015331:Cohort Studies; D004562:Electrocardiography; D004636:Emergency Service, Hospital; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000097:blood / Q000175:diagnosis* / Q000503:physiopathology; D011237:Predictive Value of Tests; D016032:Randomized Controlled Trials as Topic; D012737:Sex Factors; D013997:Time Factors; D019210:Troponin I / Q000097:blood*
chemical_list: D015415:Biomarkers; D019210:Troponin I
keywords: Accelerated diagnostic pathway; Acute coronary syndrome; Acute myocardial infarction; Emergency department; Emergency room; High sensitivity troponin; NSTEMI; Stemi