WEDNESDAY, Jan. 11 (HealthDay News) -- 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.
The findings don't mean that everyone should be tested or treated for silent atrial fibrillation (AF), but they do argue for awareness and tighter control of known stroke risk factors such as high blood pressure.
"In patients with pacemakers, we do see a very high prevalence of silent AF that is not recognized by the patient," said study author Dr. Jeff Healey, an associate professor of medicine of the Michael G. DeGroote School of Medicine at McMaster University in Ontario, Canada. "Even though they are silent, these episodes are clearly associated with risk of stroke."
Individuals who had one silent atrial fibrillation episode within the first three months of the study were twice as likely to have a stroke, when compared to their counterparts who did not experience any bouts, the study showed. An episode of atrial fibrillation was defined as an irregular heartbeat that lasted at least six minutes.
This risk increased with each additional risk for stroke such as high blood pressure and diabetes, Healey said. All participants were 65 or older and had a history of high blood pressure. Researchers followed the patients for about 2.5 years.
"We know that high blood pressure is a v
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