Atrial fibrillation patients who use the drug, warfarin, to prevent harmful blood clots from forming in their hearts to lower risk of stroke are at higher risk of developing dementia than patients who use warfarin for non-atrial fibrillation conditions, according to a new study from the Intermountain Medical Center Heart Institute.
Atrial fibrillation is an abnormal heart rhythm that raises the risk of small clots forming in the heart and leading to a stroke. Warfarin is the most common anticoagulant drug used worldwide to lower risk of the harmful clots from forming and causing stroke.
For the study, Intermountain researchers looked at more than 6,000 patients who had no history of dementia and were chronically anticoagulated using warfarin for any indication -- not just atrial fibrillation. The patients were then divided into two groups: Those with atrial fibrillation who were using warfarin, and those using warfarin who did not have atrial fibrillation.
After adjusting for multiple variations, patients with atrial fibrillation were two to three times more likely to develop dementia compared to the patients who were on warfarin, but did not have a diagnosis of atrial fibrillation.
"Atrial fibrillation patients are at higher risk of developing all forms of dementia compared to patients without atrial fibrillation. Warfarin is used to lower risk of stroke in patients with atrial fibrillation, but when the blood levels of the drug are erratic it contributes to the dementia risk. This dementia risk is observed in people with and without atrial fibrillation that are exposed to long-term warfarin treatment" said Jared Bunch, MD, lead author of the study and director of electrophysiology at the Intermountain Medical Center Heart Institute in Salt Lake City.
"Even when we consider the influence of warfarin on dementia risk, the presence of atrial fibrillation conveys additional risk of dementia. This suggests that they way we manage the abnormal heart rhythm, beyond just the practice of preventing blood clots through warfarin, may be a way we can further lower the risk of all forms of dementia, including Alzheimers disease, in patients with atrial fibrillation," Dr. Bunch added.
Results of the study will be presented during the American Heart Association Scientific Sessions in New Orleans on Tuesday, November 15, at 1:30 pm, CT.
Seven years ago, researchers from the Intermountain Medical Center Heart Institute found that patients with atrial fibrillation had much higher rates of all forms of dementia, including Alzheimer's disease. Since then, researchers have continued to explore the association between atrial fibrillation and dementia in an effort to better understand and identify ways to prevent dementia in heart patients.
"Further research is needed to identify the many complex mechanisms that link atrial fibrillation to dementia," said Dr. Bunch. "We are initiating a series of new studies that are aimed to understand what treatments may reduce the risk of developing dementia in atrial fibrillation patients."
Other members of the Intermountain Medical Center Heart Institute team include Kevin Graves, BS; Heidi T. May, PhD; Tami L. Bair, RN; Victoria Jacobs, PhD; Brian G. Crandall, MD; Michael Cutler, MD; Jeffrey S. Osborn, MD; Charles Mallender, MD; John D. Day, MD; and Peter Weiss, MD.
The Intermountain Medical Center is the flagship facility for the Intermountain Healthcare system, which is based in Salt Lake City.