The evolving role of platelet glycoprotein IIb/IIIa inhibitors in the management of acute coronary syndromes

OBJECTIVE: To briefly discuss the pathophysiology of acute coronary syndromes (ACS) and to present the clinical data currently available regarding the use of platelet glycoprotein (GP) IIb/IIIa inhibitors in the management of ACS. DATA SOURCES: Literature on antithrombotic therapy in ACS was identified using a MEDLINE search (January 1988–September 1998), along with the Agency on Health Care Policy and Research guidelines for the management of unstable angina. Abstracts from recent scientific meetings were also reviewed. STUDY SELECTION: Review articles from the cardiology literature (pathophysiology) and randomized, controlled clinical trials of currently approved platelet GP IIb/IIIa inhibitors in ACS were evaluated. Ex vivo platelet aggregation studies and pharmacology literature were also included. Abstract data were included to illustrate specific points when published literature was not available. DATA EXTRACTION: Study data were evaluated based on study design, outcome parameters, and adverse drug reactions. Clinical information from review articles was evaluated based on applicability to the treatment of ACS. DATA SYNTHESIS: Platelet adhesion and aggregation are pivotal events in the pathophysiology of ACS. The GP IIb/IIIa inhibitors represent a new and unique class of drugs that block fibrinogen and von Willebrand factor–mediated platelet aggregation, the common end point of all biologic pathways of platelet aggregation. Three agents are currently approved by the Food and Drug Administration: abciximab, a monoclonal antibody; eptifibatide, a synthetic peptide; and tirofiban, a synthetic nonpeptide. CONCLUSIONS: Clinical trial data demonstrate efficacy of all three GP IIb/IIIa inhibitors in reducing the combined end point of morbidity and mortality in patients undergoing angioplasty. Eptifibatide and tirofiban also reduce the combined end point of morbidity and mortality in patients with unstable angina. These data expand the present role of platelet GP IIb/IIIa inhibitors by providing evidence for their effectiveness in the medical treatment of ACS. However, the specific role that these agents will have in the management of ACS is yet to be fully defined.