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This discussion was selected from the weekly Grand Rounds in the Department of Medicine, University of Washington School of Medicine, Seattle. Taken from a transcription, it has been edited by Dawn E. Dewitt, MD, Chief Medical Resident, Henry Rosen,MD, Professor and Associate Chair and Paul G. Ramsey, MD, Professor and Chair of the Department of Medicine.The thromboembolic risk of atrial fibrillation varies with the underlying cause, associated heart disease, and history of previous embolism. Decisions regarding warfarin anticoagulation therapy require a careful assessment of relative risks of thromboembolism and bleeding. Anticoagulation is strongly indicated for valvular atrial fibrillation and to prevent recurrent stroke in patients with atrial fibriliation and previous stroke or transient ischemic attack. Several randomized trials have consistently shown a reduction of the risk wit, h the use of warfarin in nonvalvular atrial fibrillation, and anticoagulation is recommended. With a careful selection of patients, the risk of major bleeding on warfarin therapy is 2% to [...]

Atrial fibrillation is a common cardiac arrhythmia. It is associated with an increased risk of thromboembolism, in which a clot dislodges, travels through the bloodstream, and eventually is deposited, blocking off blood flow - usually to the brain. The risk of embolism associated with rheumatic heart disease affecting the valves is high, and is further increased when atrial fibrillation is present. The use of anticoagulant therapy can decrease the risk of embolic stroke in these patients; however, there are various viewpoints on the use of anticoagulants in patients with atrial fibrillation. A critical review of the medical literature and newly available data has led to recommendations for anticoagulation in most patients with atrial fibrillation. The overall risk of bleeding from anticoagulation therapy is approximated at 11 to 40 percent. Major bleeding may occur in the gastrointestinal, genitourinary, vaginal, respiratory, or retroperitoneal systems. The ultimate safety of anticoagulation, however, depends on the underlying cause of the atrial fibrillation. To monitor anticoagulation therapy, frequent medical visits and laboratory tests are needed. The physician must weigh the risks and benefits of anticoagulation for each patient. Anticoagulation is clearly beneficial in reducing the risk of embolism during cardioversion (induced electrical countershock) of patients with atrial fibrillation. Therapy should be instituted three weeks before the cardioversion and continue for four weeks afterwards. Other strong indicators for anticoagulation are atrial fibrillation associated with valvular disease or history of a previous embolism. Nevertheless, each patient must be assessed individually. Contraindications to anticoagulation must be examined and the benefits and risks must be critically evaluated. (Consumer Summary produced by Reliance Medical Information, Inc.)