Prognostic importance of concomitant heparin with eptifibatide in acute coronary syndromes

Platelet glycoprotein IIb/IIIa inhibitors have been extensively studied in the treatment of patients with ischemic heart disease. Data regarding the u se of these agents in the absence of concomitant intravenous heparin have b een conflicting. We sought to determine, using propensity analysis, whether the benefit of eptifibatide, a IIb/ IIIa inhibitor, in the treatment of ac ute coronary syndromes is affected by the concurrent administration of hepa rin. By trial design, patients were randomized to either eptifibatide or pl acebo, whereas use of intravenous heparin was left to the discretion of tre ating physicians, The effect of eptifibatide on the 30-day composite end po int of death or myocardial infarction was studied in patients who received heparin and those who did not. Propensity analysis methods were used to con trol for confounding and presumed selection biases. Among 5,576 patients wh o were receiving heparin when the bolus dose of the study drug was administ ered, eptifibatide wets associated with a reduced composite end point rate (13%) compared with that of placebo (14.5% vs 16.6%, p 0.03). In contrast, among 1,441 patients who were not receiving heparin, there was no differenc e in 30-day event rates with eptifibatide compared with placebo (13.7% vs 1 3.1%, p >0.7). After a propensity score for use of heparin was developed, h owever, use of heparin did not affect the reduced risk associated with epti fibatide (adjusted relative risk [RR] for heparin-eptifibatide interaction term 0.90, 95% confidence interval [CI] 0.61 to 1.32, p >0.5), but the prop ensity for heparin use was a strong predictor of events (adjusted RR 1.76, 95% CI 1.42 to 2.17, p <0.001). The use of eptifibatide independently predi cted a lower risk of events (adjusted RR 0.31, 95% CI 0.10 to 0.93, p = 0.0 4). Thus, the apparent positive impact of heparin on the benefits of eptifi batide therapy was largely due to confounding and bias. (C) 2001 by Excerpt a Medico, Inc.