Un-fractionated Heparin Versus Bivalirudin During Percutaneous Coronary Interventions (PCI) (ISAR-REACT-3)

Thrombin plays a major role in acute coronary artery occlusions during percutaneous coronary interventions. Unfractionated heparin has been traditionally used during invasive coronary procedures to reduce the risk of thrombotic occlusion. Bivalirudin, a direct antithrombin inhibitor, has several advantages over unfractionated heparin: it acts independently of antithrombin and inhibits both free and clot-bound thrombin; it is not neutralized by circulating inhibitors; exhibits consistent dose-response characteristics, and does not cause thrombocytopenia. Previous studies have shown that use of bivalirudin among patients undergoing percutaneous coronary interventions is associated with better outcomes (death, myocardial infarction, urgent repeat revascularization or in-hospital major bleeding) as compared with unfractionated heparin and adjunctive use of glycoprotein IIb/IIIa platelet receptor inhibitors. However, previous studies have included patients treated with plain balloon angioplasty or stenting after inadequate pre-treatment with thienopyridines (ticlopidine or clopidogrel). Recent guidelines recommend that all patients undergoing percutaneous coronary interventions must receive a loading dose of 300 -600 mg of clopidogrel. A 600 mg loading dose of clopidogrel eliminates the need for glycoprotein IIb/IIIa platelet receptor inhibitors in adjunct to heparin. According to existing evidence antithrombotic regimens based on either bivalirudin or pre-treatment with 600 mg of clopidogrel in addition to UFH intraprocedurally, are effective strategies to reduce ischemic and hemorrhagic complications in patients with coronary artery disease undergoing PCI. At present, it is not known whether bivalirudin is superior to UHF in patients who have been optimally pre-treated with a loading dose of clopidogrel.