The risk of ischemic stroke in nonvalvular atrial fibrillation patients is 2 to 7 times (200% to 700%) greater than in those without the disease.
Fuster V, Ryden L, Cannom D, Crijns H, et al. ACC/AHA/ESC 2006 Guidelines for the Management of Patients With Atrial Fibrillation. Am Coll Cardiol. 2006; 48: e149-246. http://circ.ahajournals.org/cgi/content/full/114/7/e257