Clinical performance of two highly sensitive cardiac troponin I assays

Abstract

BACKGROUND: The aim of this study was to compare the clinical performance of 2 sensitive cTnI assays with 10% CV imprecision below the 99th percentile upper reference limit. METHODS: We measured cardiac troponin and N-terminal pro-brain natriuretic peptide (NT-proBNP) concentrations in a random sample of the Global Use of Strategies To Open Occluded Coronary Arteries (GUSTO) IV cohort (n = 1251). Outcome data of 1-year mortality and the composite endpoint DMI [death and/or myocardial infarction (MI) within 30 days] were available in all patients. The 99th percentile of a healthy population was estimated from the Sweden Women and Men and Ischemic Heart Disease (SWISCH) cohort (n = 442). We measured cardiac troponin I (cTnI) using the Access AccuTnI (Beckman Coulter) and Centaur TnI Ultra (Siemens Healthcare Diagnostics) and NT-proBNP using the Elecsys 2010 (Roche Diagnostics). RESULTS: Applying the 10% CV cutoff, the sensitivity of the Access AccuTnI assay in identifying DMI and death was higher than that of the Centaur TnI Ultra (P = 0.02 and P < 0.001), and the AccuTnI assay also identified more patients at risk (P < 0.001) and with poor outcome. Applying the 99th percentile cutoffs, AccuTnI identified more patients at risk than the Centaur TnI (P < 0.001) and with significant differences in outcome. Significantly more patients with cardiac troponins below the cutoffs as measured by Centaur TnI had increased NT-proBNP concentrations (P < 0.001) compared with AccuTnI. CONCLUSIONS: The AccuTnI assay identified more patients at risk than the Centaur cTnI Ultra assay. Our results demonstrate the clinical potential of highsensitivity cardiac troponin assays for the identification of patients at risk of dying from cardiovascular disease. © 2008 American Association for Clinical Chemistry.