Results of a study on high-sensitivity cardiac troponin I in a stable hemodialysis patient population

Although cardiac troponin (cTn) assay is highly specific for myocardial injury, an elevated cTn level above the 99th percentile can be found in extra-cardiac diseases, such as Chronic Kidney Disease (CKD). The aim of the present study is to quantify hs-cTnI (high sensitivity cardiac troponin I) level in Hemodialysis (HD) patients, in order to define its basal value and to identify predictive factors associated with increased hs-cTnI levels after HD. Methods. 55 stable HD patients followed for at least 3 months at “Città di Lecce Hospital” and without cancer disease were studied. Troponin was determined before and after HD (pre/post HD) by VIDAS bioMérieux cTnI assay, based on ELFA method. Statistical analysis of pre/post HD values was conducted by permutation test based on Student’s t-test. The pre/post HD 99th percentiles of the population were determined by 3 methods according to CLSI C28-A3 and compared to the 99th percentile of healthy population (19 ng/L) in order to identify predictive factors for the cTnI increase by logistic binary regression. Differences were considered statistically significant at p < 0.05. Results. Values above the 99th percentile were found in 17 pre-HD patients (31%) and in 18 post-HD patients (33%). Differences between pre/post HD values were not statistically significant (p=0.218). The 99th percentiles pre-HD (104.05 ng/L) and post-HD (116.78 ng/L) were both statistically significant (p < 0.001), when compared with the 99th percentile of healthy population. Among predictive factors associated with increased hs-cTnI levels in HD patients (age, sex, diabetes, hypertension, hypercholesterolemia, smoking, BMI, previous cardiac diseases, creatininemia, e-GFR, CRP, hemoglobin and albumin levels), a weak but significant correlation was found in pre-HD as well as in post-HD only for male sex (p = 0.047; p = 0.049) and hypercholesterolemia (p = 0.040; p = 0.048). Conclusions. Our study demonstrates that, by using VIDAS cTnI assay, the pre/post HD 99th percentiles of stable HD patients are higher than the cTn values of healthy population and that the cTnI values are not significantly modified by HD treatment. Moreover, our data confirm the Fourth Universal Definition of Myocardial Infarction approach for the evaluation of ischemic damage during HD, based on a pre/post HD comparison of cTn values rather than on the increase above a pre-determined 99° percentile. Weak predictive factors of a cTnI increase are male sex and hypercholesterolemia.