title: Elevated troponin I levels but not low grade chronic inflammation is associated with cardiac-specific mortality in stable hemodialysis patients.
abstract: BACKGROUND
  Elevated cardiac troponin I (TnI) levels are associated with all-cause mortality in stable hemodialysis patients. Their relationship to cardiac-specific death has been inconsistent, and the reason for their elevation is not well understood. We hypothesized that elevated TnI levels in chronic stable hemodialysis patients more specifically track with cardiac mortality, and this mechanism is independent of other contributors of cardiac mortality, such as inflammation.
  
  
  METHODS
  We conducted a single-centre, cohort study of prevalent hemodialysis patients at a tertiary care hospital. Plasma TnI levels were measured with routine monthly blood tests in clinically stable patients for two consecutive months. Plasma TnI was measured by immunoassay and a value above the laboratory reference range (0.06 μg/L) was considered elevated. The primary outcome of death was adjudicated separately for this study, and classified as cardiac, non-cardiac, or unknown. Cox proportional hazard models were used to examine the association of TnI with the all-cause and cardiac-specific mortality, adjusting for potential confounders, including C-reactive protein (CRP) as a marker of inflammation.
  
  
  RESULTS
  Of 133 patients followed for a median of 1.7 years, there were 38 deaths (58% non-cardiac, 39% cardiac, 3% unknown). Elevated TnI was associated with adjusted HR for all-cause mortality of 2.57 (95% CI 1.30-5.09) and an adjusted HR for cardiac death of 3.14 (95% CI 1.07-9.2), after accounting for age, time on dialysis, diabetes status, prior coronary artery disease history, and C-reactive protein. Although CRP was also independently associated with all-cause mortality, it did not add prognostic information to TnI for cardiac-specific death.
  
  
  CONCLUSIONS
  Elevated TnI levels are independently associated with cardiac and all-cause mortality in asymptomatic hemodialysis patients. The mechanism for this risk is likely independent of inflammation, but may reflect chronic subclinical myocardial injury or unmask those with subclinical atherosclerotic heart disease. Whether those with elevated TnI levels may benefit from additional investigations or more aggressive therapies to treat cardiovascular disease remains to be determined.
authors.affiliation: Department of Medicine, Division of Nephrology, Royal Victoria Hospital, McGill University, 687 Pine Avenue West, Ross 2,39, Montreal, Quebec H3A 1A1, Canada. ahsan.alam@mcgill.ca.
authors.forename: Ahsan
authors.initials: A
authors.lastname: Alam
authors.forename: Andrea
authors.initials: A
authors.lastname: Palumbo
authors.forename: Istvan
authors.initials: I
authors.lastname: Mucsi
authors.forename: Paul E
authors.initials: PE
authors.lastname: Barré
authors.forename: Allan D
authors.initials: AD
authors.lastname: Sniderman
mesh_terms: D000368:Aged; D015415:Biomarkers / Q000097:blood; D015984:Causality; D015897:Comorbidity; D005260:Female; D006801:Humans; D007676:Kidney Failure, Chronic / Q000097:blood* / Q000453:epidemiology / Q000628:therapy*; D008297:Male; D009205:Myocarditis / Q000097:blood* / Q000401:mortality*; D015995:Prevalence; D011379:Prognosis; D011792:Quebec / Q000453:epidemiology; D006435:Renal Dialysis; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D015996:Survival Rate; D019210:Troponin I / Q000097:blood*
chemical_list: D015415:Biomarkers; D019210:Troponin I