Impact of Clinical Syndrome Acuity on the Differential Response to 2 Glycoprotein IIb/IIIa Inhibitors in Patients Undergoing Coronary Stenting

BACKGROUND: Although glycoprotein IIb/IIIa inhibitors have been shown to reduce periprocedural and late ischemic events in patients undergoing stent implantation, the relative safety and efficacy of different agents in this class is less established. Also unknown is whether the acuity of the presenting clinical syndrome, which may affect the degree of platelet inhibition required or achieved, influences the response to different antiplatelet agents. METHODS AND RESULTS: A prospective, multicenter, double-blind, randomized trial was performed in which 4809 patients undergoing planned stenting were randomized to receive abciximab or tirofiban. In patients with acute coronary syndromes (ACS; n=3025), abciximab resulted in lower rates of myocardial infarction at 30 days (5.8% versus 8.5%; P=0.004) and 6 months (7.2% versus 9.8%; P=0.013), although 6-month mortality rates were identical (1.39% in both groups; P=0.99). Conversely, in patients without ACS (n=1784), myocardial infarction rates were not significantly lower with tirofiban, survival was similar, and target vessel revascularization was reduced, which translated into a trend toward enhanced 6-month event-free survival with tirofiban (89.7% versus 86.6%; P=0.056). CONCLUSIONS: In patients with ACS undergoing stent implantation, abciximab use compared with tirofiban results in greater suppression of periprocedural myonecrosis, although a survival benefit has not been demonstrated. Patients with stable coronary syndromes may have equivalent or better outcomes with tirofiban relative to abciximab, with fewer adverse hematologic and hemorrhagic events. These data raise important issues regarding the relative pharmacodynamic inhibition of platelet function required in varying clinical scenarios and have important implications for the cost-effective utilization of glycoprotein IIb/IIIa inhibitors.