High-sensitivity troponin T improves the prognostic value of N-terminal pro-B-type natriuretic peptide in patients with stable coronary artery disease: results from the LURIC Study

BACKGROUND: Cardiac troponin T is an established prognostic marker in patients with acute coronary syndromes, but not in stable coronary artery disease (CAD) like N-terminal pro-B-type natriuretic peptide (NT-proBNP). We examined the additive prognostic value of a high-sensitivity troponin T (hsTnT) assay to predict adverse clinical outcomes in stable CAD. METHODS: A retrospective nested case-control analysis of 256 patients with stable CAD who participated in the LURIC study: 128 cases who died from cardiovascular causes during a median follow-up of 7.5 years and 128 survivors (controls) matched for age and gender, were included. hsTnT and NT-proBNP were determined in baseline samples using immunoassays (Roche Diagnostics, Germany). RESULTS: Sixty-two percent of the 256 subjects exhibited concentrations of hsTnT≥14 ng/L, the manufacturer recommended cut-off to diagnose myocardial infarction in patients with acute chest pain. hsTnT, NT-proBNP, diabetes mellitus and fasting glucose were associated with cardiovascular mortality in univariate analysis. Logistic regression identified hsTnT and NT-proBNP as independent risk markers. Receiver operator characteristic (ROC) curves analysis identified optimal cut-offs at 15 ng/L and 352 μg/L for hsTnT (AUC 0.728, p<0.05) and NT-proBNP (AUC 0.751, p=0.07), respectively. Patients with one or two positive markers exhibited 5-year cardiovascular mortalities of 40% and 60%, respectively, compared to 10% in patients with negative markers. The addition of hsTnT to NT-proBNP significantly increased c-statistics of proportional hazards calculated from survival times as well as net reclassification indexes. CONCLUSIONS: Many patients with stable CAD exhibited increased concentrations of hsTnT. The combined determination of NT-proBNP and hsTnT was superior for risk stratification compared to determining either marker alone.