title: High-sensitivity cardiac troponin I at presentation in patients with suspected acute coronary syndrome: a cohort study.
abstract: BACKGROUND
  Suspected acute coronary syndrome is the commonest reason for emergency admission to hospital and is a large burden on health-care resources. Strategies to identify low-risk patients suitable for immediate discharge would have major benefits.
  
  
  METHODS
  We did a prospective cohort study of 6304 consecutively enrolled patients with suspected acute coronary syndrome presenting to four secondary and tertiary care hospitals in Scotland. We measured plasma troponin concentrations at presentation using a high-sensitivity cardiac troponin I assay. In derivation and validation cohorts, we evaluated the negative predictive value of a range of troponin concentrations for the primary outcome of index myocardial infarction, or subsequent myocardial infarction or cardiac death at 30 days. This trial is registered with ClinicalTrials.gov (number NCT01852123).
  
  
  RESULTS
  782 (16%) of 4870 patients in the derivation cohort had index myocardial infarction, with a further 32 (1%) re-presenting with myocardial infarction and 75 (2%) cardiac deaths at 30 days. In patients without myocardial infarction at presentation, troponin concentrations were less than 5 ng/L in 2311 (61%) of 3799 patients, with a negative predictive value of 99·6% (95% CI 99·3-99·8) for the primary outcome. The negative predictive value was consistent across groups stratified by age, sex, risk factors, and previous cardiovascular disease. In two independent validation cohorts, troponin concentrations were less than 5 ng/L in 594 (56%) of 1061 patients, with an overall negative predictive value of 99·4% (98·8-99·9). At 1 year, these patients had a lower risk of myocardial infarction and cardiac death than did those with a troponin concentration of 5 ng/L or more (0·6% vs 3·3%; adjusted hazard ratio 0·41, 95% CI 0·21-0·80; p<0·0001).
  
  
  CONCLUSIONS
  Low plasma troponin concentrations identify two-thirds of patients at very low risk of cardiac events who could be discharged from hospital. Implementation of this approach could substantially reduce hospital admissions and have major benefits for both patients and health-care providers.
  
  
  BACKGROUND
  British Heart Foundation and Chief Scientist Office (Scotland).
authors.affiliation: BHF Centre for Cardiovascular Science, University of Edinburgh, Edinburgh, UK. Electronic address: anoop.shah@ed.ac.uk.
authors.forename: Anoop S V
authors.initials: AS
authors.lastname: Shah
authors.affiliation: BHF Centre for Cardiovascular Science, University of Edinburgh, Edinburgh, UK.
authors.forename: Atul
authors.initials: A
authors.lastname: Anand
authors.affiliation: Division of Cardiology, Department of Medicine, Hennepin County Medical Center, Minneapolis, MN, USA.
authors.forename: Yader
authors.initials: Y
authors.lastname: Sandoval
authors.affiliation: BHF Centre for Cardiovascular Science, University of Edinburgh, Edinburgh, UK.
authors.forename: Kuan Ken
authors.initials: KK
authors.lastname: Lee
authors.affiliation: Department of Emergency Medicine, Hennepin County Medical Center, Minneapolis, MN, USA; Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, MN, USA.
authors.forename: Stephen W
authors.initials: SW
authors.lastname: Smith
authors.affiliation: BHF Centre for Cardiovascular Science, University of Edinburgh, Edinburgh, UK.
authors.forename: Philip D
authors.initials: PD
authors.lastname: Adamson
authors.affiliation: BHF Centre for Cardiovascular Science, University of Edinburgh, Edinburgh, UK.
authors.forename: Andrew R
authors.initials: AR
authors.lastname: Chapman
authors.affiliation: BHF Centre for Cardiovascular Science, University of Edinburgh, Edinburgh, UK.
authors.forename: Timothy
authors.initials: T
authors.lastname: Langdon
authors.affiliation: BHF Centre for Cardiovascular Science, University of Edinburgh, Edinburgh, UK.
authors.forename: Dennis
authors.initials: D
authors.lastname: Sandeman
authors.affiliation: BHF Centre for Cardiovascular Science, University of Edinburgh, Edinburgh, UK.
authors.forename: Amar
authors.initials: A
authors.lastname: Vaswani
authors.affiliation: BHF Centre for Cardiovascular Science, University of Edinburgh, Edinburgh, UK.
authors.forename: Fiona E
authors.initials: FE
authors.lastname: Strachan
authors.affiliation: BHF Centre for Cardiovascular Science, University of Edinburgh, Edinburgh, UK.
authors.forename: Amy
authors.initials: A
authors.lastname: Ferry
authors.affiliation: BHF Centre for Cardiovascular Science, University of Edinburgh, Edinburgh, UK.
authors.forename: Alexandra G
authors.initials: AG
authors.lastname: Stirzaker
authors.affiliation: Department of Biochemistry, Queen Elizabeth University Hospital, Glasgow, UK.
authors.forename: Alan
authors.initials: A
authors.lastname: Reid
authors.affiliation: Department of Emergency Medicine, Royal Infirmary of Edinburgh, Edinburgh, UK.
authors.forename: Alasdair J
authors.initials: AJ
authors.lastname: Gray
authors.affiliation: Division of Clinical Sciences, St George's, University of London, London, UK.
authors.forename: Paul O
authors.initials: PO
authors.lastname: Collinson
authors.affiliation: Centre for Population Health Sciences, University of Edinburgh, Edinburgh, UK.
authors.forename: David A
authors.initials: DA
authors.lastname: McAllister
authors.affiliation: Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, MN, USA.
authors.forename: Fred S
authors.initials: FS
authors.lastname: Apple
authors.affiliation: BHF Centre for Cardiovascular Science, University of Edinburgh, Edinburgh, UK.
authors.forename: David E
authors.initials: DE
authors.lastname: Newby
authors.affiliation: BHF Centre for Cardiovascular Science, University of Edinburgh, Edinburgh, UK.
authors.forename: Nicholas L
authors.initials: NL
authors.lastname: Mills
mesh_terms: D054058:Acute Coronary Syndrome / Q000097:blood / Q000175:diagnosis*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000097:blood / Q000175:diagnosis*; D011379:Prognosis; D011446:Prospective Studies; D012307:Risk Factors; D012606:Scotland; D012680:Sensitivity and Specificity; D019210:Troponin I / Q000097:blood*
chemical_list: D019210:Troponin I