Stroke and Atrial Fibrillation

Patients with atrial fibrillation (AF) have a 5-fold increased risk for stroke compared with individuals without AF. According to some estimates, 15% of ischemic strokes are associated with AF. Risk factors for stroke in patients with AF include age ≥ 75 years, hypertension, congestive heart failure, diabetes, and prior stroke or transient ischemic attack (TIA). Prevention of systemic embolism and ischemic stroke is an important aspect of the management of patients with AF. Evidence-based guidelines recommend antithrombotic (anticoagulation, antiplatelet) therapy for patients with AF based on the presence of risk factors. The vitamin K antagonist warfarin (target international normalized ratio [INR] 2.5) is recommended for patients considered at high risk for stroke; warfarin is also recommended for patients with 2 or more moderate risk factors for stroke; and either aspirin (75-325 mg/day) or warfarin is recommended for patients with less validated or weaker risk factors. Aspirin therapy is advised for AF patients without risk factors. There is a large body of evidence demonstrating the reduced risk of stroke and death associated with warfarin treatment in patients with AF, however many patients who could potentially benefit are not being treated with warfarin. Barriers to the use of warfarin include the narrow therapeutic range, the risk of bleeding versus benefit, frequent monitoring of INR, drug/drug and drug/food interactions, inadequate appreciation of clinical trial data, and questions regarding long term benefits of treatment. Lack of patient understanding of the reasons for warfarin therapy may also factor into poor guideline adherence. New treatment approaches in development for stroke prevention in patients with AF include direct thrombin inhibitors, Factor Xa inhibitors and non-pharmacological approaches such as percutaneous left atrial appendage occluders. Improvements in risk assessment and better utilization of anticoagulation therapy for patients with AF at risk for stroke should enhance patient outcomes.

Gladstone D, et al. Potentially preventable strokes in high-risk patients with atrial fibrillation who are not adequately anticoagulated. Stroke. 2009;40:235-240.

Maisel W. Left atrial appendage occlusion - closure or just the beginning? N Engl J Med. 2009;360(25):2601-2603.

Singer D, et al. Antithrombotic therapy in atrial fibrillation. Chest. 2008;133:546S-592S.

Yip G, Lim H. Atrial fibrillation and stroke prevention. Lancet Neurol. 2007;6:981-993.