Background: New highly sensitive (hs) assays have challenged the interpretation of cardiac troponins (cTn). The present study was designed to evaluate simultaneously conventional cTnT and cTnI together with their corresponding highly sensitive determinations in stable hemodialysis (HD) patients. Ability of cTn to stratify HD patient risk was assessed.
Methods: A total of 224 stable HD patients was included in this observational study. cTnT and hs-cTnT were measured using Roche cTnT/hs-cTnT assays based on a Cobas e601® analyzer. cTnI and hs-cTnI were measured using Beckman AccuTnI/hs-TnI IUO assays on Access II system. Patients were followed up prospectively during 9 years. Relationship between cTn level and mortality was assessed through Cox survival analysis.
Results: The median cTnT and cTnI concentrations were 38.5 ng/L (IQR, 18.8-76) and 10 ng/L (IQR, 10-20), respectively. The median hs-cTnT and hs-cTnI concentrations were 62.5 ng/L (IQR, 38.8-96.3) and 13.9 ng/L (IQR, 8.4-23.6), respectively. The prevalence of values above the 99th percentile was significantly more marked with cTnT (85.3 and 97.8% for conventional and hs cTnT, respectively) than with cTnI (7.6 and 67.4% for conventional and hs cTnI, respectively). During the follow-up, 167 patients died, mainly from cardiac cause (n=77). The optimized cut-off values, determined by bootstrap method, predicting mortality were 38, 69, 20 and 11 ng/L for cTnT, hs-cTnT, cTnI and hs-cTnI, respectively. After full adjustment, elevated plasma concentrations of all troponin were significant predictors of mortality.
Conclusions: A large proportion of patients free of acute coronary syndrome (ACS) has hs-cTn I or T higher than the 99th percentile which could be seen as a limiting factor for ACS screening. However, all generation and type of troponin assays could be reliable indicators of prognosis risk in HD patients.