title: Diagnostic and prognostic utility of troponin estimation in patients presenting with syncope: a prospective cohort study.
abstract: OBJECTIVE
  To primarily assess the value of troponin I to identify acute myocardial infarction (AMI), and second, to predict 1-month serious outcome or all-cause death in patients presenting with syncope to the Emergency Department (ED).
  
  
  METHODS
  Prospective cohort study of all adult patients presenting to the ED after an episode of syncope.
  
  
  METHODS
  In admitted patients, plasma troponin I was measured 12 h after syncope, and in discharged patients, between 12 h and 7 days following discharge. Primary endpoints were the diagnosis of AMI, and the composite endpoint of serious outcome or all-cause death at 1 month.
  
  
  RESULTS
  Over an 8-month period, 289 patients were recruited. Troponin I was obtained in 186 admitted patients and was elevated in 13 (7%), and obtained in 103 discharged patients and was raised in only one (1%). Four patients had an AMI (1.4%) and all had ischaemic electrocardiographic (ECG) changes on their presenting ED ECG (ST segment deviation or pathological Q waves) that were 100% sensitive and 72% specific for AMI with a 100% negative predictive value. Seven of the 14 patients (50%) with a raised troponin I had a serious outcome that did not include AMI, or all-cause death compared with 16 of the 267 patients (6%) without a raised troponin (p<0.0001).
  
  
  CONCLUSIONS
  AMI is infrequent (1.4%), and estimation of troponin I provides little additional benefit to the presenting ED ECG in identifying patients with syncope due to AMI. Troponin I should not be used to rule out AMI in adult patients presenting with isolated syncope. Troponin I may predict 1-month serious outcome or all-cause death in syncope.
authors.affiliation: Emergency Department, Royal Infirmary of Edinburgh, 51 Little France Crescent, Edinburgh EH16 4SA, UK. mattreed1@hotmail.com
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Reed
authors.forename: David E
authors.initials: DE
authors.lastname: Newby
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Coull
authors.forename: Robin J
authors.initials: RJ
authors.lastname: Prescott
authors.forename: Alasdair J
authors.initials: AJ
authors.lastname: Gray
mesh_terms: D000208:Acute Disease; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000097:blood; D002423:Cause of Death; D015331:Cohort Studies; D004630:Emergencies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000175:diagnosis* / Q000401:mortality; D011379:Prognosis; D011446:Prospective Studies; D013575:Syncope / Q000097:blood*; D019210:Troponin I / Q000097:blood*
chemical_list: D015415:Biomarkers; D019210:Troponin I