title: Comparison of cardiac troponins I and T measured with high-sensitivity methods for evaluation of prognosis in atrial fibrillation: an ARISTOTLE substudy.
abstract: BACKGROUND
  Although cardiac troponin is associated with outcomes in atrial fibrillation (AF), the complementary prognostic information provided by cardiac troponin I (cTnI) and cTnT is unknown. This study investigated the distribution, determinants, and prognostic value of cTnI and cTnT concentrations in patients with AF.
  
  
  METHODS
  Samples were collected. At the time of randomization, we analyzed cTnI and cTnT concentrations of 14806 AF patients in the Apixaban for Reduction in Stroke and Other Thromboembolic Events in Atrial Fibrillation (ARISTOTLE) trial using high-sensitivity assays. Correlations (Spearman), determinants (multivariable linear regression), and outcomes (adjusted Cox models and c-statistics) were investigated.
  
  
  RESULTS
  Concentrations of cTnI and cTnT were correlated (r = 0.70) and measurable in most participants [cTnI 98.5% (median 5.4 ng/L, ≥99th percentile in 9.2%) and cTnT 93.5% (median 10.9 ng/L, ≥99th percentile in 34.4%)]. Renal impairment was the most important factor affecting the concentrations of both troponins. cTnI increase was more associated with heart failure, vascular disease, and persistent/permanent AF, and cTnT with age, male sex, and diabetes. Over a median 1.9 years of follow-up, patients with both troponins above the median had significantly higher risk for stroke/systemic embolism [hazard ratio (HR) 1.72 (95% CI 1.31-2.27)], cardiac death [3.14 (2.35-4.20)], and myocardial infarction [2.99 (1.78-5.03)] than those with both troponins below median (all P < 0.005). Intermediate risks were observed when only 1 troponin was above the median. When combined with clinical information, each marker provided similar prognostication and had comparable c-index.
  
  
  CONCLUSIONS
  cTnI and cTnT concentrations are moderately correlated and measurable in plasma of most AF patients. The risk of stroke and cardiovascular events is highest when both troponins are above median concentrations. Each troponin provides comparable prognostic information when combined with clinical risk factors. ClinicalTrials.gov/NCT00412984.
authors.affiliation: Uppsala Clinical Research Center, Department of Medical Sciences, Cardiology, and ziad.hijazi@ucr.uu.se.
authors.forename: Ziad
authors.initials: Z
authors.lastname: Hijazi
authors.affiliation: Uppsala Clinical Research Center, Department of Medical Sciences, Clinical Chemistry, Uppsala University, Uppsala, Sweden;
authors.forename: Agneta
authors.initials: A
authors.lastname: Siegbahn
authors.affiliation: Uppsala Clinical Research Center.
authors.forename: Ulrika
authors.initials: U
authors.lastname: Andersson
authors.affiliation: Uppsala Clinical Research Center, Department of Medical Sciences, Cardiology, and.
authors.forename: Bertil
authors.initials: B
authors.lastname: Lindahl
authors.affiliation: Duke University, Medical Center, Durham, NC;
authors.forename: Christopher B
authors.initials: CB
authors.lastname: Granger
authors.affiliation: Duke University, Medical Center, Durham, NC;
authors.forename: John H
authors.initials: JH
authors.lastname: Alexander
authors.affiliation: Department of Cardiology, Oslo University Hospital and Faculty of Medicine, Institute for Clinical Medicine, University of Oslo, Oslo, Norway;
authors.forename: Dan
authors.initials: D
authors.lastname: Atar
authors.affiliation: Mayo Clinic College of Medicine, Rochester, MN;
authors.forename: Bernard J
authors.initials: BJ
authors.lastname: Gersh
authors.affiliation: Bristol-Myers Squibb, Princeton, NJ;
authors.forename: Michael
authors.initials: M
authors.lastname: Hanna
authors.affiliation: Division of Emergency Care, Department of Medicine, Helsinki University Central Hospital, Helsinki, Finland;
authors.forename: Veli-Pekka
authors.initials: VP
authors.lastname: Harjola
authors.affiliation: University of Adelaide, Adelaide, Australia;
authors.forename: John
authors.initials: J
authors.lastname: Horowitz
authors.affiliation: Medical Department, Hospital Unit West, Herning/Holstbro, Denmark;
authors.forename: Steen
authors.initials: S
authors.lastname: Husted
authors.affiliation: Boston University Medical Center, Boston, MA;
authors.forename: Elaine M
authors.initials: EM
authors.lastname: Hylek
authors.affiliation: Duke University, Medical Center, Durham, NC;
authors.forename: Renato D
authors.initials: RD
authors.lastname: Lopes
authors.affiliation: BHF Cardiovascular Research Centre, University of Glasgow, Glasgow, Scotland, U.K.
authors.forename: John J V
authors.initials: JJ
authors.lastname: McMurray
authors.affiliation: Uppsala Clinical Research Center, Department of Medical Sciences, Cardiology, and.
authors.forename: Lars
authors.initials: L
authors.lastname: Wallentin
mesh_terms: D000368:Aged; D001281:Atrial Fibrillation / Q000097:blood* / Q000150:complications* / Q000175:diagnosis; D002318:Cardiovascular Diseases / Q000097:blood / Q000175:diagnosis / Q000209:etiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D012307:Risk Factors; D020521:Stroke / Q000097:blood / Q000175:diagnosis / Q000209:etiology*; D019210:Troponin I / Q000097:blood*; D020107:Troponin T / Q000097:blood*
chemical_list: D019210:Troponin I; D020107:Troponin T