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Bivalirudin for Acute Coronary Syndromes

Patients with ACS who undergo early invasive management have similar frequencies of ischemic events with heparin plus a GpI or with bivalirudin alone, but bleeding is less common with bivalirudin.

Treatment for acute coronary syndromes (unstable angina and myocardial infarction [MI] without ST-segment elevation) consists of angiography followed by percutaneous coronary intervention, surgical intervention (coronary-artery bypass grafting), or medical management. Patients usually receive pharmacotherapy that includes aspirin, clopidogrel, a platelet glycoprotein IIb/IIIa inhibitor (GpI), and an antithrombotic agent, such as unfractionated heparin (UH) or low-molecular-weight heparin (LMWH). Recently, an alternative antithrombotic agent — fondaparinux (Arixtra, an ultra-low-molecular-weight heparin) was evaluated. Fondaparinux is similar to the LMWH enoxaparin in reducing risk for ischemic events, but it was associated with substantially less major bleeding and with improved long-term morbidity and mortality (Journal Watch Apr 7 2006).

Now results on a new agent, bivalirudin (Angiomax), are available. Bivalirudin is a direct thrombin inhibitor that is related to hirudin (leech anticoagulant). Bivalirudin reversibly blocks both the catalytic and fibrin-binding exosites of thrombin and has a half-life of only 25 minutes, making it ideal for the short-term prevention of thrombotic events. In the international, industry-sponsored Acute Catheterization and Urgent Intervention Triage Strategy (ACUITY) trial, researchers randomized 13,819 ACS patients to UH/enoxaparin plus a GpI, bivalirudin plus a GpI, or bivalirudin alone.

At 30 days after randomization, no difference was noted in the combined rate of ischemic outcomes (MI, unplanned revascularization, or death) among the groups, but major bleeding was less common in the bivalirudin-only group than in the UH-plus-GpI and bivalirudin-plus-GpI groups (3.0% vs. 5.7% and 5.3%; P=0.001). In a subgroup analysis of patients who did not receive clopidogrel prior to angiography, patients in the bivalirudin-only group had a 1.29-fold greater risk for ischemic events than did patients whose regimens included GpIs (P=0.05).

Comment: These results show that patients with ACS who undergo early invasive management have similar frequencies of ischemic events whether they are treated with heparin plus a GpI or with bivalirudin alone, but bivalirudin treatment yields a lower rate of major bleeding. As long as patients receive potent antiplatelet agents (e.g., aspirin, clopidogrel), long-term antithrombotic therapy might not even be required.

— David Green, MD, PhD

Published in Journal Watch Oncology and Hematology December 11, 2006

Citation(s):

Stone GW et al. Bivalirudin for patients with acute coronary syndromes. N Engl J Med 2006 Nov 23; 355:2203-16.

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