Randomized, Placebo-Controlled Study of Lamifiban with Thrombolytic Therapy for the Treatment of Acute Myocardial Infarction: Rationale and Design for the Platelet Aggregation Receptor Antagonist Dose Investigation and Reperfusion Gain in Myocardial Infarction (PARADIGM) Study.

The benefits of thrombolytic therapy in the treatment of acute myocardial infarction are incontrovertible. Large-scale studies combining angiographic and clinical end-points have demonstrated a perfusion-mortality relationship, with the highest survival rate among patients with early restoration of TIMI grade 3 coronary arterial flow. Despite advances in thrombolytic strategies, a substantial number of patients fail to rapidly achieve and maintain adequate coronary perfusion with thrombolysis. Conjunctive therapy with aspirin has proven useful in thrombolytic regimens, likely countering the heightened platelet activity central to acute coronary syndromes. The antiplatelet effect of aspirin is relatively weak compared with that of glycoprotein IIb/IIIa platelet receptor antagonists, which block the final common pathway of platelet aggregation. Lamifiban is a nonpeptide glycoprotein IIb/IIIa receptor antagonist. In early experimental studies, Lamifiban in combination with thrombolytic therapy has been shown to effectively restore coronary arterial patency, and phase I and phase II data have shown its use to be safe. To determine the optimal dose with regard to safety and efficacy of Lamifiban to be used with thrombolytic therapy in a large-scale trial, a phase II study is underway. The Platelet Aggregation Receptor Antagonist Dose Investigation and Reperfusion Gain in Myocardial Infarction (PARADIGM) study is a randomized, placebo-controlled study of Lamifiban in 400 patients receiving thrombolysis as treatment for acute myocardial infarction. By studying 90-minute angiography, platelet aggregation, continuous electrocardiography, and clinical outcome in PARADIGM, important insights will be obtained to determine the optimal dose of Lamifiban for phase III study. We provide the background and rationale for the study of Lamifiban in PARADIGM and other ongoing studies in acute coronary syndromes.