Elevation in serum troponin I predicts the benefit of tirofiban

Background: Elevations in serum troponins among patients with acute coronar y syndromes have been shown to identify those patients who are at high risk for poor outcome and who accrue larger relative benefits from aggressive a ntiplatelet and antithrombotic therapies. We studied a group of patients fr om the PRISM-PLUS trial to explore whether simply using serum troponin I, a serum marker of cardiac injury, could predict benefit of GP IIb/IIIa recep tor antagonism with tirofiban. Methods and Results: For this study, the subjects consisted of 55 patients receiving the combination therapy of tirofiban/heparin, and 55 receiving he parin alone. The baseline characteristics were similar between the two trea tment groups. Serial blood samples were obtained over the first 24-hour per iod following randomization to study drug, and were analyzed for troponin I (TnI) levels. Among those patients with elevated serum TnI (>0.5 ng/ml), t he 30-day event rate for death or myocardial infarction (MI) was reduced fr om 20.6% among the heparin only group to 3.6% for those treated with the co mbination of tirofiban/heparin, an absolute risk reduction of 17% and relat ive risk reduction of 83% (p=0.06). Among the TnI negative patients, the ra tes of death/MI at 30 days were 9.5% and 11.1% among the combination and he parin treated groups respectively (p=NS). Conclusion: Irrespective of high-risk clinical factors, including ST segmen t depression, these data support the hypothesis that serum troponins identi fy those who benefit from aggressive antiplatelet therapy with tirofiban.