title: Frequency and clinical implications of discordant creatine kinase-MB and troponin measurements in acute coronary syndromes.
abstract: OBJECTIVE
  We sought to evaluate the association between discordant cardiac marker results and in-hospital mortality and treatment patterns in patients with non-ST-segment elevation acute coronary syndromes (NSTE ACS).
  
  
  BACKGROUND
  Creatine kinase-MB (CK-MB) and cardiac troponins (cTn) are often measured concurrently in patients with NSTE ACS. The significance of discordant CK-MB and cTn results is unknown.
  
  
  METHODS
  Among 29,357 ACS patients in the CRUSADE initiative who had both CK-MB and cTn measured during the first 36 hours, we examined relationships of four marker combinations (CK-MB-/cTn-, CK-MB+/cTn-, CK-MB-/cTn+, and CK-MB+/cTn+) with mortality and American College of Cardiology/American Heart Association guidelines-recommended acute care.
  
  
  RESULTS
  The CK-MB and cTn results were discordant in 28% of patients (CK-MB+/cTn-, 10%; CK-MB-/cTn+, 18%). In-hospital mortality was 2.7% among CK-MB-/cTn- patients; 3.0%, CK-MB+/cTn-; 4.5%, CK-MB-/cTn+; and 5.9%, CK-MB+/cTn+. After adjustment for other presenting risk factors, patients with CK-MB+/cTn- had a mortality odds ratio (OR) of 1.02 (95% confidence interval [CI] 0.75 to 1.38), those with CK-MB-/cTn+ had an OR of 1.15 (95% CI 0.86 to 1.54), and those with CK-MB+/cTn+ had an OR of 1.53 (95% CI 1.18 to 1.98). Despite variable risk, patients with CK-MB+/cTn- and CK-MB-/cTn+ were treated similarly with early antithrombotic agents and catheter-based interventions.
  
  
  CONCLUSIONS
  Among patients with NSTE ACS, an elevated troponin level identifies patients at increased acute risk regardless of CK-MB status, but an isolated CK-MB+ status has limited prognostic value. Recognition of these risk differences may contribute to more appropriate early use of antithrombotic therapy and invasive management for all cTn+ patients.
authors.affiliation: Division of Cardiology and Duke Clinical Research Institute, Duke University Medical Center, Durham, North Carolina 27715-7969, USA. newby001@mc.duke.edu
authors.forename: L Kristin
authors.initials: LK
authors.lastname: Newby
authors.forename: Matthew T
authors.initials: MT
authors.lastname: Roe
authors.forename: Anita Y
authors.initials: AY
authors.lastname: Chen
authors.forename: E Magnus
authors.initials: EM
authors.lastname: Ohman
authors.forename: Robert H
authors.initials: RH
authors.lastname: Christenson
authors.forename: Charles V
authors.initials: CV
authors.lastname: Pollack
authors.forename: James W
authors.initials: JW
authors.lastname: Hoekstra
authors.forename: W Frank
authors.initials: WF
authors.lastname: Peacock
authors.forename: Robert A
authors.initials: RA
authors.lastname: Harrington
authors.forename: Robert L
authors.initials: RL
authors.lastname: Jesse
authors.forename: W Brian
authors.initials: WB
authors.lastname: Gibler
authors.forename: Eric D
authors.initials: ED
authors.lastname: Peterson
mesh_terms: D000368:Aged; D015415:Biomarkers / Q000097:blood; D052279:Creatine Kinase, MB Form / Q000097:blood*; D005260:Female; D017052:Hospital Mortality; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D017202:Myocardial Ischemia / Q000097:blood* / Q000188:drug therapy / Q000401:mortality*; D016017:Odds Ratio; D011379:Prognosis; D012680:Sensitivity and Specificity; D016019:Survival Analysis; D014336:Troponin / Q000097:blood*
chemical_list: D015415:Biomarkers; D014336:Troponin; D052279:Creatine Kinase, MB Form