Evaluation of the AccuTnI Cardiac Troponin I Assay for Risk Assessment in Acute Coronary Syndromes

Effective risk assessment guides appropriate triage and therapy for patients with suspected unstable angina or non-ST-elevation myocardial infarction (MI) (1)(2). Cardiac biomarkers play a valuable role in risk stratification in non-ST-elevation acute coronary syndromes (NSTE ACS). In particular, the cardiac troponins have been identified as the preferred biomarkers for this purpose (1). Clinical application of cardiac troponin I (cTnI) has been complicated by a lack of standardization across the multiple commercially available assays, which has produced substantial variation in the reported clinical decision limits. As such, clinical appraisal of the prognostic performance of each cTnI assay is important to providing an evidence-based guide to its use for risk assessment. The most recent generation cTnI assay from Beckman Coulter (AccuTnITM) uses antibodies directed at a stable region (amino acids 30–110) of the NH2 terminus of cTnI and delivers very good analytic performance (3)(4). We evaluated this assay for the assessment of the short-term risk of death and recurrent ischemic events among patients with suspected NSTE ACS enrolled in the Orbofiban in Patients with Unstable Coronary Syndromes (OPUS)-Thrombolysis in Myocardial Infarction (TIMI) 16 trial. OPUS-TIMI 16 was a multicenter, randomized, parallel-group trial comparing an oral glycoprotein IIb/IIIa inhbitor with placebo for patients with ACS. The design and results of OPUS-TIMI 16 have been reported (5). The protocol was approved by the Institutional Review Board of each participating hospital, and all patients signed written informed consent. Patients were included if they presented within 72 h of symptom onset and had at least one of the following: dynamic electrocardiographic changes; increased cardiac markers; history of coronary artery disease; or age ≥65 with diabetes or vascular disease. Patients were randomized to placebo or one of two orbofiban doses. The present substudy was conducted in all patients with NSTE ACS …