What is the effectiveness of VKAs in reducing stroke risk?
VKAs with warfarin have been found to reduce the primary event rate in the randomized SPAF trial (Stroke Prevention in Atrial Fibrillation Study) by 67% (7.4% to 2.3%) and was found to be superior to treatment with aspirin alone, which reduced the primary event rate by 42%. Furthermore, in all scoring systems of stroke risk in AF, prior stroke or TIA alone places a patient in a risk category in which anticoagulation is recommended.