Atrial fibrillation and anticoagulation

Abstract

Atrial fibrillation (AF) increases the risk of ischemic stroke due to the formation of a thrombus within left atrium. Thus, adjusted-dose (optimal INR: 2-3) anticoagulant therapy such as warfarin dramaticaly decreases this risk of embolic events both in primary and secondary prevention but slightly increases the risk of bleeding, particularly in the elderly. This explains that, although the benefit has been clearly demonstrated, the anticoagulant therapy remains underused. The efficacy of low doses of aspirin is less clear but it may be appropriate in younger patients with lone AF because of a low risk of embolic events. The combination of low doses of warfarin and aspirin should not be given. In case of contraindication to warfarin and aspirin, some others drugs such as indobufen or dipyridamole may be given but the most promising drug is ximelagatran, a direct thrombin inhibitor, which appears to be as effective than warfarin with a lower incidence of bleedings. For patients in AF who require urgent cardioversion, intravenous unfractionated heparin remains the anticoagulant of choice but an approach combining low-molecular-weight heparin and transesophageal echocardiography has been proposed. For each patient the decision of treatment must be tightly correlated to the benefit-risk ratio.