[Risk stratification for thromboembolism and antithrombotic prophylaxis in atrial fibrillation].

Atrial fibrillation (AF) is associated with a significantly high risk of stroke and systemic embolism (4.5%/year). Oral anticoagulant therapy (OAT) with warfarin (INR range 2.0-3.0) significantly reduces thromboembolic risk, whereas aspirin has poor efficacy. In patients with AF, several scoring systems, such as the CHADS2 and CHA2DS2-VASc scores, are currently used to stratify thromboembolic risk. The CHA2DS2-VASc score stratifies patients at intermediate-low thromboembolic risk more accurately than the CHADS2 score. The most recent European and US guidelines on AF have extended the indications for OAT, which is recommended not only for patients at high risk, but also for those at intermediate risk, with CHADS2 score ≥1. However, in clinical practice underuse of OAT, suboptimal quality of anticoagulation, and frequent discontinuations of treatment are observed. Therefore, there is a great expectation for the new oral anticoagulants, in particular the direct thrombin inhibitor dabigatran etexilate and the factor Xa inhibitors rivaroxaban and apixaban, which are at least non-inferior to warfarin and safer, and seem to be a suitable therapeutic alternative to the old warfarin.