Though the percentages are small, millions of people have atrial fibrillation, so the difference could mean avoiding thousands of cases of dementia, Day said.
Patients who had catheter ablation also had a lower risk of stroke and death. About 2.2 percent who had ablation had a stroke compared to 4.7 percent of those treated with medication. About 6 percent of patients ablation patients died, compared to 23.5 percent treated by medications.
"The risk of dying, the risk of stroke, the risk of dementia and Alzheimer's disease were all significantly reduced in the patients who underwent an ablation procedure than those treated with medications -- so much so that the long term risk was as if they did not have atrial fibrillation at all," Day said.
The findings were to be presented May 13 at Heart Rhythm 2010, the Heart Rhythm Society's annual scientific meeting, in Denver.
Dr. Richard L. Page, president of the Heart Rhythm Society and chair of the department of medicine at University of Wisconsin School of Medicine in Madison, said the reasons for the link between Alzheimer's and atrial fibrillation are still not well understood. While the study is important, only a randomized clinical trial could prove definitively that ablation helps ward off dementia.
It's possible people who did not get ablation were already weaker or had some subtle signs of dementia to begin with that made doctors, patients and their families opt against the treatment, Page said.
"We can't conclude that the ablations reduced the risk of those outcomes, but it raises the possibility," he said.
After ablation, about 64 percent of people with atrial fibrillation no longer had the arrhythmia or needed to take medications for arrhythmia at the end of the three years, the team found.
Symptoms of atrial fibrillation can include rapid and irregular heartbeat,
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