title: Changes in diagnosing non-ST-segment elevation myocardial infarction after the introduction of a new high-sensitivity cardiac troponin T assay: a single-centre experience.
abstract: BACKGROUND
  Cardiac troponins are the most sensitive and specific biochemical markers of myocardial injury and with the new high-sensitivity troponin methods very minor injuries of the heart muscle can be detected. The introduction of high-sensitivity assays has facilitated reference range adjustments and a revised cut-off point for myocardial infarction (MI) due to an improved performance in the lower concentration range. The objective of this study was to investigate whether implementing a high-sensitivity cardiac troponin T (hs-cTnT) assay with subsequent lowering of the cut-off point changed the hospital evaluation and diagnosis of acute non-ST-segment elevation myocardial infarction (NSTEMI) in a general hospital population.
  
  
  METHODS
  NSTEMI patients admitted to our hospital during two periods each lasting one year were retrospectively compared. During period 1 (August 2007 - July 2008) patients were diagnosed with a conventional troponin T assay, and during period 2 (August 2009 - July 2010) patients were diagnosed using an hs-cTnT assay.
  
  
  RESULTS
  A significant increase in the number of NSTEMI admissions was observed using the hs-cTnT assay (225 vs. 341, risk ratio 1.57, 95% confidence interval 1.33 to 1.85). The proportion of patients examined with acute coronary angiography was similar (25.8% vs. 23.8%). Due to the higher number of NSTEMI admissions the total number of angiographies was higher in period 2 (58 vs. 81, p < 0.05), and significantly more patients were examined without signs of coronary artery disease (CAD) (0% vs. 8.6%, p < 0.05). A smaller proportion diagnosed with the high-sensitivity assay had significant dynamic cTnT changes between the highest and lowest cTnT measurement during each admission (96.2% vs. 88.7%, p < 0.01).
  
  
  CONCLUSIONS
  More patients were diagnosed with NSTEMI and underwent coronary angiography after introducing the hs-cTnT assay. At the same time there was an increase in the frequency of coronary angiograms without signs of CAD, and fewer had significant dynamic cTnT concentration changes.
authors.affiliation: Department of Cardiology, Lovisenberg Diakonale Hospital, Oslo, Norway. tshall@online.no
authors.forename: Trygve Sørdahl
authors.initials: TS
authors.lastname: Hall
authors.forename: Jonas
authors.initials: J
authors.lastname: Hallén
authors.forename: Stefan
authors.initials: S
authors.lastname: Agewall
authors.forename: Dan
authors.initials: D
authors.lastname: Atar
authors.forename: Torstein
authors.initials: T
authors.lastname: Jensen
mesh_terms: D000368:Aged; D002637:Chest Pain / Q000097:blood / Q000175:diagnosis* / Q000503:physiopathology; D017023:Coronary Angiography; D003937:Diagnosis, Differential; D004562:Electrocardiography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000097:blood / Q000175:diagnosis* / Q000503:physiopathology; D012016:Reference Values; D012189:Retrospective Studies; D014218:Triage / Q000379:methods; D020107:Troponin T / Q000097:blood*
chemical_list: D020107:Troponin T