Many people may not feel their heart race when they are having an irregular heartbeat known as atrial fibrillation, but these silent symptoms double their risk of stroke, a new study finds. Of 2,580 study participants with pacemakers who did not have a history of atrial fibrillation, more than one-third experienced pacemaker-documented episodes that lasted for more than six minutes, researchers said. However, 85 percent of these people did not realize it because there were no obvious symptoms. Pacemakers are placed in the chest to control abnormal heart rhythms. The results appear in the Jan. 12 issue of the New England Journal of Medicine.
