Troponin I as a prognostic marker of cardiac events in asymptomatic hemodialysis patients using a sensitive troponin I assay

Abstract

Elevated troponin T is known to be a prognostic marker for long-term cardiac events and mortality in asymptomatic end-stage renal disease patients. There are conflicting data in this regard with respect to troponin I (TnI). We recently showed a high incidence of elevated TnI levels in asymptomatic hemodialysis (HD) patients using a new generation sensitive TnI assay. The aim of this pilot study was to explore the prognostic value of TnI, as measured with this new assay, as a marker for outcomes in HD patients over a 2-year follow-up period. Fifty-one asymptomatic HD patients were enrolled, and pre-dialysis TnI levels were checked once monthly over 3 consecutive months. Patients were considered to be in the TnI positive group if TnI level on any of the three draws was ≥0.035 ng/ml. All patients were followed for a period of 2 years. The primary end points were acute coronary syndrome, coronary revascularization, sudden death, or cardiac arrest. The secondary end point was all-cause mortality. Elevated TnI levels were found in 51% (26/51) of patients in our cohort. One TnI positive patient was subsequently lost to follow up. There were 6 cardiac events over 2 years, all of which were in the troponin positive group (6/25 or 24%). The presence of a positive TnI at baseline was significantly associated with future cardiac events (p=0.022). A prior history of coronary artery disease (CAD) was also significantly related to future cardiac events (p=0.010). No patient with negative TnI at baseline developed a cardiac event, while 45.5% of those with both a positive TnI and a history of CAD had an event. Fourteen deaths occurred over 2 years, 8 in TnI positive and 6 in the negative group. All-cause mortality was not associated with elevated TnI levels at baseline. We found a significant association between positive TnI and subsequent cardiac events in asymptomatic HD patients followed for 2 years. TnI levels, as measured with a sensitive assay, may be useful in assessing cardiac risk in asymptomatic HD patients. This needs further confirmation in a larger cohort.