title: Subclinical elevation of high-sensitive troponin T levels at the convalescent stage is associated with increased 5-year mortality after ST-elevation myocardial infarction.
abstract: BACKGROUND
  It is unclear whether serum high-sensitive troponin T (hs-TnT) levels at the convalescent stage of ST-elevation myocardial infarction (STEMI) are associated with long-term mortality.
  
  
  METHODS
  This study enrolled a total of 2944 consecutive STEMI patients who were registered in the Osaka Acute Coronary Insufficiency Study between 2000 and 2009, and whose hs-TnT levels were evaluated at the convalescent stage. Patients were divided into four hs-TnT category groups according to the results of survival classification and regression tree (CART) analysis. The impact of hs-TnT levels on 5-year mortality was evaluated using multivariate Cox regression analysis.
  
  
  RESULTS
  Only one patient had hs-TnT level below the detection limit of the assay (<0.003ng/mL). The median hs-TnT level was 0.025 (quartile 0.011-0.083)ng/mL. During the median follow-up period of 1782 days, 188 patients died. Survival CART analysis revealed that the 1st, 2nd, and 3rd discriminating hs-TnT levels to discern 5-year mortality were 0.028, 0.008, and 1.340ng/mL, respectively. The adjusted hazard ratios for the medium-low (0.009-0.028ng/mL), medium-high (0.029-1.340ng/mL), and high-risk (≥1.341ng/mL) groups were 3.03 (95% confidence interval 1.18-7.77, p=0.021), 4.29 (1.63-11.28, p=0.003), and 8.68 (2.20-34.27, p=0.002), respectively. Integrated discrimination improvement (IDI) analysis revealed that incorporation of this hs-TnT classification scheme with other clinical variables statistically improved the discriminatory accuracy for 5-year mortality, with a time-dependent IDI of 0.0076 (p=0.033).
  
  
  CONCLUSIONS
  hs-TnT levels at the convalescent stage were associated with long-term mortality in STEMI patients. Even subclinical elevation of hs-TnT levels was associated with increased 5-year mortality.
authors.affiliation: Department of Medical Innovation, Osaka University Hospital, Suita, Japan; Department of Cardiovascular Medicine, Osaka University Graduate School of Medicine, Suita, Japan.
authors.forename: Masahiko
authors.initials: M
authors.lastname: Hara
authors.affiliation: Department of Cardiovascular Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan; Department of Advanced Cardiovascular Therapeutics, Osaka University Graduate School of Medicine, Suita, Japan. Electronic address: sakatayk@cardio.med.tohoku.ac.jp.
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Sakata
authors.affiliation: Department of Cardiovascular Medicine, Osaka University Graduate School of Medicine, Suita, Japan.
authors.forename: Daisaku
authors.initials: D
authors.lastname: Nakatani
authors.affiliation: Department of Cardiovascular Medicine, Osaka University Graduate School of Medicine, Suita, Japan.
authors.forename: Shinichiro
authors.initials: S
authors.lastname: Suna
authors.affiliation: Division of Cardiology, Osaka Rosai Hospital, Sakai, Japan.
authors.forename: Masami
authors.initials: M
authors.lastname: Nishino
authors.affiliation: School of Human Welfare Studies, Kwansei Gakuin University, Nishinomiya, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Sato
authors.affiliation: Division of Environmental Medicine and Population Sciences, Department of Social and Environmental Medicine, Osaka University Graduate School of Medicine, Suita, Japan.
authors.forename: Tetsuhisa
authors.initials: T
authors.lastname: Kitamura
authors.affiliation: Department of Cardiovascular Medicine, Osaka University Graduate School of Medicine, Suita, Japan; Department of Advanced Cardiovascular Therapeutics, Osaka University Graduate School of Medicine, Suita, Japan.
authors.forename: Shinsuke
authors.initials: S
authors.lastname: Nanto
authors.affiliation: Office of Biostatistics and Data Management, National Cerebral and Cardiovascular Center, Suita, Japan.
authors.forename: Toshimitsu
authors.initials: T
authors.lastname: Hamasaki
authors.affiliation: Osaka Prefectural Hospital Organization, Osaka Medical Center for Cancer and Cardiovascular Diseases, Osaka, Japan.
authors.forename: Masatsugu
authors.initials: M
authors.lastname: Hori
authors.affiliation: Department of Cardiovascular Medicine, The University of Tokyo Graduate School of Medicine, Tokyo, Japan.
authors.forename: Issei
authors.initials: I
authors.lastname: Komuro
mesh_terms: D000368:Aged; D003289:Convalescence; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000097:blood* / Q000401:mortality / Q000473:pathology; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012044:Regression Analysis; D016019:Survival Analysis; D020107:Troponin T / Q000097:blood*
chemical_list: D020107:Troponin T
keywords: Classification and regression tree; High-sensitive troponin T; Integrated discrimination improvement; Mortality; ST-elevation myocardial infarction