Troponin T as a risk marker for recurrent cardiovascular events in the post-discharge setting one month after acute coronary syndrome: a TRACER substudy

Abstract Background Troponin T (TnT) is a protein found in cardiac myocytes that is released during myocardial injury, such as myocardial infarction (MI). TnT levels rapidly rise during an MI, remain elevated for several days, and are a key criterion for diagnosing MI. Additionally, circulating TnT levels may offer prognostic information later, particularly during the rehabilitation phase after an acute coronary syndrome (ACS). Purpose To examine the relationship between circulating TnT at one month after hospitalisation for ACS and subsequent cardiovascular (CV) events. Methods The TRACER trial randomly assigned 12,944 patients diagnosed with non-ST-segment elevation ACS (NSTE-ACS) to receive either vorapaxar or placebo. Plasma samples were obtained after one month, and high-sensitivity (hs)-TnT was measured among 5,313 patients using the Elecsys electrochemiluminescence immunoassays. In this sub-study, the primary composite endpoint was the one-year risk of CV mortality, MI, or ischaemic stroke. Associations with outcomes were evaluated using Cox regression models, both unadjusted and adjusted for clinical baseline characteristics. Results The median concentration of hs-TnT was 11 ng/L one month after hospitalisation for ACS. Higher levels of hs-TnT at one month were associated with older age, coronary artery bypass surgery during the index ACS, male sex, a history of heart failure, renal disease, and diabetes mellitus. The composite outcome of CV mortality, MI, or ischaemic stroke occurred in 381 patients (incidence rate 5.4 per 100 person-years). Hs-TnT at one month after ACS was independently associated with the risk of the composite CV endpoint (relative hazard ratio with 95% confidence interval comparing the third vs. the first sample quartile: 2.40 [1.80 – 3.20]) (see Figure 2). Similarly, hs-TnT, when added to a model including established risk factors, increased the concordance index of the multivariable model from 0.711 to 0.740 (p<0.001). The results were consistent across the different components of the composite endpoint. Conclusions The level of hs-TnT provides useful information on the risk of future CV events in patients when measured one month after an ACS. This information might be useful for optimising secondary preventive treatment following an ACS.Figure.Hs-TnT and composite CV outcome