Appropriate Use of Glycoprotein IIb/IIIa Blockade for Unstable Angina and Non–ST Segment Elevation Myocardial Infarction

• Objective: To review the clinical trials of glycoprotein IIb/IIIa (GPIIb/IIIa) inhibitors for unstable angina or non–ST segment elevation myocardial infarction (MI) and to provide a practice guide for the use of these agents in this setting. • Methods: Clinical trials relating to GPIIb/IIIa antagonists and acute coronary syndromes were identified from a MEDLINE search of articles published between 1994 and 2001 and from presentations made during the official meetings of the American College of Cardiology, American Heart Association, and the European Heart Society in 1999 and 2000. Clinical trials related to ST segment elevation were excluded. • Results: Eleven clinical trials were identified, 7 relating to intravenous GPIIb/IIIa inhibitors and 4 relating to oral GPIIb/IIIa inhibition. When combined with aspirin and unfractionated heparin, eptifibatide and tirofiban improved clinical outcomes in patients with unstable angina or non–ST segment elevation MI, especially in the context of early revascularization. Abciximab was beneficial only as an adjunct to percutaneous coronary intervention. Oral chronic GPIIb/IIIa inhibition was associated with increased mortality in each of the clinical trials that were completed. • Conclusion: Barring the inherent differences in their structures and pharmacokinetics, both tirofiban and eptifibatide improve clinical outcomes of patients with unstable angina or non–ST segment elevation myocardial infarction, regardless of revascularization strategy, while abciximab plays a pivotal role in percutaneous coronary intervention for acute coronary syndromes. For oral GPIIb/IIIa inhibitors, more investigation is required to better understand the biologic properties of these drugs before further clinical testing.