title: Utility of absolute and relative changes in cardiac troponin concentrations in the early diagnosis of acute myocardial infarction.
abstract: BACKGROUND
  Current guidelines for the diagnosis of acute myocardial infarction (AMI), among other criteria, also require a rise and/or fall in cardiac troponin (cTn) levels. It is unknown whether absolute or relative changes in cTn have higher diagnostic accuracy and should therefore be preferred.
  
  
  RESULTS
  In a prospective, observational, multicenter study, we analyzed the diagnostic accuracy of absolute (Δ) and relative (Δ%) changes in cTn in 836 patients presenting to the emergency department with symptoms suggestive of AMI. Blood samples for the determination of high-sensitive cTn T and cTn I ultra were collected at presentation and after 1 and 2 hours in a blinded fashion. The final diagnosis was adjudicated by 2 independent cardiologists. The area under the receiver operating characteristic curve for diagnosing AMI was significantly higher for 2-hour absolute (Δ) versus 2-hour relative (Δ%) cTn changes (area under the receiver operating characteristic curve [95% confidence interval], high-sensitivity cTn T: 0.95 [0.92 to 0.98] versus 0.76 [0.70 to 0.83], P<0.001; cTn I ultra: 0.95 [0.91 to 0.99] versus 0.72 [0.66 to 0.79], P<0.001). The receiver operating characteristic curve-derived cutoff value for 2-hour absolute (Δ) change was 0.007 μg/L for high-sensitivity cTn T and 0.020 μg/L for cTn I ultra (both cutoff levels are half of the 99th percentile of the respective cTn assay). Absolute changes were superior to relative changes in patients with both low and elevated baseline cTn levels.
  
  
  CONCLUSIONS
  Absolute changes of cTn levels have a significantly higher diagnostic accuracy for AMI than relative changes, and seem therefore to be the preferred criteria to distinguish AMI from other causes of cTn elevations.
  
  
  BACKGROUND
  URL: http://www.clinicaltrials.gov. UNIQUE IDENTIFIER: NCT00470587.
authors.affiliation: From the Departments of Cardiology, Kantonsspital Olten, Olten, Switzerland.
authors.forename: Tobias
authors.initials: T
authors.lastname: Reichlin
authors.forename: Affan
authors.initials: A
authors.lastname: Irfan
authors.forename: Raphael
authors.initials: R
authors.lastname: Twerenbold
authors.forename: Miriam
authors.initials: M
authors.lastname: Reiter
authors.forename: Willibald
authors.initials: W
authors.lastname: Hochholzer
authors.forename: Hanna
authors.initials: H
authors.lastname: Burkhalter
authors.forename: Stefano
authors.initials: S
authors.lastname: Bassetti
authors.forename: Stephan
authors.initials: S
authors.lastname: Steuer
authors.forename: Katrin
authors.initials: K
authors.lastname: Winkler
authors.forename: Federico
authors.initials: F
authors.lastname: Peter
authors.forename: Julia
authors.initials: J
authors.lastname: Meissner
authors.forename: Philip
authors.initials: P
authors.lastname: Haaf
authors.forename: Mihael
authors.initials: M
authors.lastname: Potocki
authors.forename: Beatrice
authors.initials: B
authors.lastname: Drexler
authors.forename: Stefan
authors.initials: S
authors.lastname: Osswald
authors.forename: Christian
authors.initials: C
authors.lastname: Mueller
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019540:Area Under Curve; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000097:blood* / Q000175:diagnosis*; D017410:Practice Guidelines as Topic; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D013997:Time Factors; D019210:Troponin I / Q000097:blood*; D020107:Troponin T / Q000097:blood*
chemical_list: D019210:Troponin I; D020107:Troponin T