Anticoagulant therapy in acute coronary syndromes

Thrombus formation on a disrupted atherosclerotic coronary artery plaque is the usual event that precipitates acute coronary syndromes (ACS). Anticoagulation therapy with unfractionated heparin, in addition to antiplatelet therapy with aspirin, decreases the risk of myocardial infarction and death with ACS. However, unfractionated heparin has pharmacological limitations that limit efficacy and safety. Low-molecular-weight heparins (enoxaparin), direct thrombin inhibitors (bivalirudin) and Factor Xa inhibitors (fondaparinux) are new anticoagulant therapy options with either superior efficacy or improved safety over unfractionated heparin. Compared with unfractionated heparin, enoxaparin and fondaparinux are easier to administer, do not require monitoring and facilitate longer treatment duration. Bivalirudin offers advantages for patients undergoing percutaneous revascularization. Careful attention to dosing and excellent vascular access site management are required to decrease the risk of bleeding and blood transfusion, which have been associated with increased mortality risk.