Evaluation of the sensitivity of two highly sensitive troponin assays for early detection of non ST- elevation myocardial infarction (NSTEMI)

Background. The major clinical role for the cardiac troponin in the MI diagnosis is in patients with nondiagnostic initial ECG (suspected NSTEMI). The aim of this study was to evaluate the clinical sensitivity of two highly sensitive last generation troponin assays (Siemens Advia TnI-ULTRA and Roche Diagnostics Cobas e411 hsTnT) in the diagnosis of patients presenting with recent NSTEMI in comparison to a conventional troponin assay. Methods. The study group consisted of 150 patients admitted to the Emergency Department with suspected acute coronary syndrome, to whom serial blood samples were taken every 3 h throughout the first 6 h after hospital admission. After evaluation of clinical history, ECG, and standard troponin results, obtained blinded to the results of tested troponin assays, 31 patients were diagnosed as NSTEMI. Positive results were considered valueshigher than 40 ng/L for TnI-ULTRA and 15 ng/L for hsTnT, respectively. Results. Sensitivities for NSTEMI were 81%, 87%, and 58% at admission and 100%, 100%, and 94% after 6h for TnI-ULTRA, hsTnT, andstandard assay, respectively. Interestingly, withboth highly sensitive assays the maximal 100% sensitivity was already reached 3h after admission. Conclusions. New highly sensitive troponin assays may significantly shorten the time to rule out NSTEMI. Although preliminary, our data suggest that the observation period of patients with suspected myocardial damage can be reduced from the conventional 12 h from hospital admission to only 3h. Accordingly, a new protocol, sampling at presentation and 3 h after, could be recommended.