[Acetylsalicylic acid versus coumarin derivatives in atrial fibrillation].

Atrial fibrillation is a chronic disorder, which significantly increases the risk of stroke. The risk of stroke largely depends on cardiac failure, age, sex, the presence of hypertension and a history of previousthromboembolism. In low risk patients with atrial fibrillation stroke can effectively be prevented with acetylsalicylic acid (100-200 mg/day). With increasing stroke risk coumarin derivatives are more effective than acetylsalicylic acid and its use has an acceptable bleeding risk. The target international normalized ratio (INR) should be between 2.0 and 3.0.