Both warfarin and the atrial fibrillation it's often used to treat may raise risk, study suggests



WebMD News from HealthDay

By Amy Norton


HealthDay Reporter


THURSDAY, May 5, 2016 (HealthDay News) -- People with the heart rhythm disorder atrial fibrillation may have a heightened risk of developing dementia -- and the quality of their drug treatment may play a role, a new study hints.

Specifically, researchers found, patients on the clot-preventing drug warfarin showed a higher dementia risk if their blood levels of the medication were frequently too high or too low.

And that was true not only for people with atrial fibrillation, but also for those using warfarin for other reasons.

Dr. Jared Bunch, the lead researcher on the study, said the findings uncover two potential concerns: People with atrial fibrillation may face an increased risk of dementia, independent of warfarin use, but warfarin might also contribute to dementia if the doses are not optimal.

"If people's levels of warfarin were erratic, their dementia risk was higher, whether they had AF or not," said Bunch, who was scheduled to present his findings Thursday at the Heart Rhythm Society's annual meeting, in San Francisco.

The results do not prove that either atrial fibrillation or warfarin are to blame, according to Bunch, a cardiologist at Intermountain Medical Center, in Murray, Utah.

But, he said, there is reason to believe that both could contribute to dementia -- in part because of effects on blood flow to the brain.

Atrial fibrillation is a common arrhythmia, affecting about 3 million U.S. adults, according to the Heart Rhythm Society. In it, the upper chambers of the heart quiver instead of contracting efficiently. The condition is not immediately life-threatening, but it can cause blood clots to form in the heart. If a clot breaks free and lodges in an artery supplying the brain, that can trigger a stroke.

Because of that, people with atrial fibrillation often take medications that cut the risk of blood clots. Those include aspirin or anticoagulants such as warfarin (Coumadin).

Warfarin is a tricky drug to take, Bunch explained: People need regular blood tests to make sure their warfarin levels are in the "therapeutic range" -- high enough to prevent clots, but low enough to avoid internal bleeding. The doses typically have to be changed over time.



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