Ablation of AF Reduces Risk of Alzheimer's Disease and Dementia

May 18, 2010

May 18, 2010 (Denver, Colorado) Treating atrial fibrillation (AF) with radiofrequency catheter ablation significantly reduces the risk of Alzheimer's disease, and reduces the risk of developing all forms of dementia, according to the results of a new study [1]. In addition to these findings, researchers showed that catheter ablation reduced the risk of mortality and stroke at three years [2].

"The good news from this study is that if you can potentially get rid of atrial fibrillation, not only does it make patients feel better, but it might also have a significant benefit as far as the long-term rates of stroke, helping to prevent premature death, as well as to reduce the risk of dementia and Alzheimer's disease," lead investigator Dr John Day (Heart Institute of Intermountain Medical Center, Salt Lake City, UT) told heartwire .

The researchers presented the results of the study, which included 37 908 patients from the Intermountain Medical Center, here at the Heart Rhythm Society 2010 Scientific Sessions. The same researchers previously established a link between Alzheimer's disease, dementia, and atrial fibrillation, with recently published results showing that AF is a powerful predictor of subsequent Alzheimer's disease [3]. Day explained that among patients who develop both AF and Alzheimer's disease, the rate of cognitive decline is rapid, and mortality rates are very high.

"With the current study, we wanted to ask: What happens if we intervene?" he said. "Can we change these long-term outcomes?"

Data From the Intermountain Medical Center

Among the 37 908 patients included in the analysis were 4212 consecutive patients who underwent AF ablation, 16 848 age- and sex-matched patients with AF who were treated with best medical therapy, and 16 848 age- and sex-matched controls without AF.

After three years of follow-up, Alzheimer's disease, documented by a neurologist who assessed patients with cranial imaging, developed in 293 patients. The rate of Alzheimer's disease and all forms of dementia, however, was significantly lower among patients who underwent catheter ablation.

Rates of Alzheimer's Disease and Dementia at Three Years

End point AF, no ablation No AF AF, ablation p value
Alzheimer's disease (%) 0.9 0.5 0.2 <0.001
Other dementia (%) 1.7 0.7 0.4 <0.001
Mortality (%) 23.5 8.7 6.0 <0.001
Stroke (%) 4.7 2.4 2.2 <0.001

"When we looked at the three-year outcomes, what we found was that the rate of Alzheimer's disease, and all forms of dementia, was reduced in the patients who had undergone a catheter ablation procedure," said Day. "In fact, the rates we saw were similar to those that you'd see in patients who never had atrial fibrillation to begin with. There was a statistically significant difference in comparing ablation patients with atrial fibrillation patients treated with best medical therapy."

Mortality, as well as stroke rates, was significantly lower among the ablation patients. To heartwire , however, Day said that clinicians are eagerly anticipating the results of Catheter Ablation vs Antiarrhythmic Drug Therapy for Atrial Fibrillation (CABANA), a study that will involve up 3000 patients followed for an estimated five years. The primary end point of the trial is total mortality; secondary end points are other cardiovascular events.

"That study just launched and we're still four or five years away before we're going to see those results," he said. "Until that study is available, these data are really the best we have."

Possible Mechanisms of Ablation Benefit

Asked about the mechanisms by which catheter ablation might reduce the risk of Alzheimer's disease, Day noted that AF could compromise cerebral perfusion, and by eliminating it, catheter ablation might improve overall hemodynamics. He also said there could be an inflammatory connection, with both AF and Alzheimer's disease associated with high levels of C-reactive protein. By increasing inflammation, AF might accelerate the inflammation-mediated progressive cognitive decline. Finally, he said, AF might cause subclinical strokes, with microscopic emboli undetected by MRI leading to the development of amyloid plaque that characterizes Alzheimer's disease.

"It's purely speculative, but this study shows that if we can potentially get rid of atrial fibrillation altogether with catheter ablation, we might be able to change the long-term outcomes," said Day. "It certainly could raise the question that if you have atrial fibrillation and medication isn't working, maybe we should move toward a potentially curative procedure earlier, rather than spinning our wheels for years with medication."

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