Context

In the treatment of non-ST-segment elevation acute coronary syndromes (NSTEACS), antithrombotic therapies are indispensible, and a large percentage of these patients undergo diagnostic coronary angiography and percutaneous coronary intervention (PCI). The traditional cornerstone of the antithrombotic regimen in patients with NSTEACS is unfractionated heparin (UFH). Unfortunately, achieving optimal anticoagulation with UFH is difficult, and up to 10% of patients treated with UFH who undergo PCI experience bleeding.1 In an effort to increase the safety of the medical and interventional treatment of NSTEACS, there has been great interest in the use of alternative anticoagulant agents.2

Fondaparinux is an indirect Factor Xa inhibitor that was initially studied for this application in the Fifth Organization to Assess Strategies in Acute Ischemic Syndromes (OASIS-5).3 Compared with enoxaparin, the use of fondaparinux resulted in a significant reduction in mortality at 1 and 6 months that was largely attributed to the 50% reduction (4.2% vs 2.2%, p<0.001) in bleeding. However, rates of guide catheter thrombosis were greater in patients receiving fondaparinux (0.9% vs 0.4%, p=0.01) in OASIS-5, as well as in the OASIS-6 trial of fondaparinux during ST-segment elevation myocardial infarction (MI). In both studies, thrombus formation during PCI was more frequent than in historical studies using UFH, raising concern that pure factor Xa inhibition provides insufficient antihrombotic therapy during PCI. A strategy for decreasing the rate of guide catheter thrombosis …