[New antithrombotics for atrial fibrillation].

Cerebral infarction is the most serious complication of atrial fibrillation. Coumarin derivatives (vitamin K antagonists) counteract systemic thromboembolism and reduce the risk of stroke by more than 60%, but carry a risk of serious bleeding. Antiplatelet therapy and subcutaneous low-molecular-weight heparin are as yet not sufficiently effective and are associated with a bleeding risk similar to vitamin K antagonists. Vitamin K antagonists require intensive INR monitoring to ensure efficacy and safety. In the past decade, oral agents have been developed that directly inhibit the activity of thrombin (factor IIa) and of activated factor X (Xa), which is the first compound in the final common pathway of the coagulation cascade. These do require INR monitoring and have rapid onset and offset of action. The first results with thrombin blockers, such as dabigatran, look promising in efficacy and safety and Xa inhibitors are currently under investigation in atrial fibrillation in 3 large clinical trials. Long-term safety of the new agents in patients with atrial fibrillation has not yet been determined.