Use of the centaur TnI-Ultra assay for detection of myocardial infarction and adverse events in patients presenting with symptoms suggestive of acute coronary syndrome

BACKGROUND: We determined the diagnostic accuracy of the Advia Centaur TnI-Ultra assay for detecting myocardial infarction (MI) and assessing risk of adverse events in patients presenting with ischemic symptoms suggestive of acute coronary syndrome. METHODS: We measured cardiac troponin I (cTnI) on admission and 6-24 h after admission (follow-up) in plasma specimens from 371 consecutive patients. The end point was the first of cardiac event or death within 60 days. We estimated survival curves using the Kaplan-Meier method and compared groups with the log rank statistic. RESULTS: MI was established in 49 patients (13%). Clinical sensitivities and specificities for MI based on the 99th percentile (0.04 mu tg/L) were 74% and 84%, respectively, on admission and 94% and 81% at follow-up. ROC curves showed significantly higher accuracy for MI in the follow-up specimen compared with admission (P = 0.001). Overall there were 2 cardiac deaths, I noncardiac death, 49 MIS, 7 coronary artery bypass grafts, and 36 percutaneous coronary interventions in 59 patients during follow-up. The event rate in those with cTnI <0.006 mu g/L was significantly lower than in groups with cTnI 0.006-0.04 mu g/L, >0.04-0.10 mu g/L, or >0.10 mu g/L (2.8% vs 11.1%) 24.1%, 55.1%, respectively; P <0.0001). Relative risks for the increasing cTnI cutoff groups were 3.9 (95% CI 1.2-13), 8.9 (2.4-34), and 25 (7.3-82) after adjustment for age, diabetes, history of hypertension, previous MI, and estimated glomerular filtration rate. CONCLUSIONS: The TnI-Ultra assay is a sensitive, early diagnostic biomarker for MI and an independent predictor of adverse events at any measurable cTnI in patients with symptoms of acute coronary syndrome. (c) 2008 American Association for Clinical Chemistry.