Use of platelet glycoprotein IIb/IIIa inhibitors has become more widespread in percutaneous coronary revascularization because of their demonstrated ability in randomized trials to decrease rates of mortality and myocardial infarction. Topol and colleagues compared the safety and efficacy of tirofiban and abciximab.

A large number of patients were enrolled in this randomized study (a total of 4,809 patients), because the statistical comparison of two active agents was more difficult than a simple assessment of one active treatment versus placebo. Study enrollees came from 149 hospitals in 18 countries and were recruited from patients undergoing elective or urgent percutaneous angioplasty and stenting. Patients with concurrent myocardial infarction, ST-segment elevation on electro-cardiography, or cardiogenic shock were excluded.

All patients received heparin, aspirin, and clopidogrel during the procedure and were continued on the two oral agents for 30 days postprocedure. Use of tirofiban or abciximab was randomized for intravenous infusion starting just before the revascularization procedure.

The comparison specified by the study design was the combined rates of death, myocardial infarction, or urgent need for repeat revascularization within 30 days of the original procedure. The abciximab group had a lower combined rate of these adverse outcomes than the tirofiban group (6.0 versus 7.6 percent). For the three outcomes, the relative increased risk for tirofiban was similar (hazard ratios of 1.21, 1.27, and 1.26 for death, myocardial infarction and revascularization, respectively). Major bleeding complications were uncommon (0.8 percent of patients), and there was no statistically significant difference between the two agents.

The authors conclude that tirofiban offered less protection than abciximab from adverse coronary outcomes after percutaneous revascularization. Most of the absolute benefit of abciximab was attributable to the lower myocardial infarction rate (particularly large infarctions) occurring with this therapy.

editors note: This is one of many studies where the “statistically significant” moniker and the substantial relative difference (27 percent more problem outcomes with tirofiban) between two treatments needs to be taken in context with modest absolute difference in the occurrence of an uncommon adverse event (i.e., only 1.6 percent difference in problem events that happened overall in less than 10 percent of patients). Cost, availability, and local expertise will be other important factors to consider in selection of a specific platelet inhibitor in any given patient.—b.z.