Antithrombotic therapy in atrial fibrillation

Abstract

Data from the Framingham study have shown that atrial fibrillation is an independent risk factor for systemic embolism. Several clinical trials have been published, evaluating the value of antithrombotic therapy for prevention of systemic embolism in this group of patients. The pooled results of these trials revealed that for every 1000 patients treated, anticoagulants could prevent 30 strokes, while aspirin prevented 18 strokes, annually. Although no randomized trials directly comparing different intensities of oral anticoagulation in patients with atrial fibrillation have been published, an INR target of 2.0 to 3.0 seems appropriate. The development of risk stratification schemes to categorize the risk of stroke in patients with atrial fibrillation will help clinicians to identify those patients who will benefit the most from oral anticoagulation. Patients who have been in atrial fibrillation for more than 48 hours should be given oral anticoagulation for three weeks before elective (electrical or pharmacological) cardioversion. Oral anticoagulation should be continued until normal sinus rhythm has been maintained for 4 weeks. Patients with atrial flutter should be treated in a similar manner to that used for patients with atrial fibrillation.