Oral anticoagulants for preventing stroke in patients with non-valvular atrial fibrillation and no previous history of stroke or transient ischemic attacks

Oral anticoagulants prevent stroke and death in people with atrial fibrillation. Atrial fibrillation is an irregularity of the heartbeat that leads to blood clots forming in the upper chambers of the heart (the atria). These clots can break free and travel through the blood stream to the brain and cause a stroke. Anticoagulant drugs, such as warfarin, slow blood clotting. The degree of inhibition of blood clotting during warfarin treatment is measured by a blood test called the international normalized ratio (INR). Dosages of warfarin that lead to INRs of 2.0 to 2.6 reduce death and stroke when given to patients with atrial fibrillation. Oral anticoagulants can cause bleeding into the brain and elsewhere. However, provided that there is careful control of dosage (requiring INR measurements at least monthly with warfarin), the risk of serious bleeding is low. The decision about whether or not to use oral anticoagulants in patients with atrial fibrillation is guided by a number of factors, including the individual's risk of stroke, which varies widely among patients with atrial fibrillation. Most people with atrial fibrillation should be considered for treatment with oral anticoagulants based on their risk of stroke, ability to tolerate anticoagulation without bleeding, and access to adequate anticoagulation monitoring.