Oral anticoagulation alone or in combination with aspirin: risks and benefits.

The combination of oral anticoagulants with antiplatelet agents has been advocated as particularly efficient in prophylaxis of arterial thromboembolism. The indications at issue are nonrheumatic chronic atrial fibrillation, mechanical and biological heart valve prostheses, coronary artery disease, coronary stents and peripheral arterial occlusive disease. However, such a combined prophylaxis might also be associated with a higher bleeding risk. Clinical trials addressing administration of coumarines with antiaggregants are rare and inhomogeneous. The present article reviews the literature on oral anticoagulants combined with aspirin in the prevention and treatment of arterial thromboembolism and draws a comparison to oral anticoagulation alone and aspirin alone, respectively. It clearly shows that this potentially dangerous combination should not be recommended in most indications until specifically designed trials have addressed its benefit-to-risk ratio.