Study shows that new blood thinners are as effective as warfarin for atrial fibrillation patients — and decrease patients' risk of dementia and stroke

Researchers at the Intermountain Medical Center Heart Institute analyzed 5,254 patients over a four-year time period from June 2010 - December 2014. Patients had similar history of a prior stroke or mini stroke. The majority of these patients were receiving treatment to prevent dangerous blood clotting for atrial fibrillation, a very common abnormal heart rhythm that up to 20 percent of elderly adults will develop. One the most devastating consequences of atrial fibrillation is stroke.

Half of the patient’s received direct oral anticoagulant medications (apixaban, dabigatran, or rivaroxaban) Eliquis, Pradaxa, or Xarelto and the other half of the patients received warfarin. 

Following patients taking anticoagulants for more than 541 days, researchers found new onset dementia and stroke rates were 51 percent less compared to when patients were taking warfarin. Overall patients treated with a direct oral anticoagulant medication were 15 percent less likely to die compared to those on warfarin, largely due to a reduction in risk of dementia, stroke, and bleeding. 

The Intermountain Medical Center Heart Institute research team reported their findings at the 2015 American Heart Association in Orlando on Sunday.  

Atrial Fibrillation is associated with 25 percent of strokes and when a stroke occurs in someone with the abnormal heart rhythm it is often more disabling. Over the past 60 years, warfarin has been used as a standard of care to prevent stroke in people who have atrial fibrillation.

In atrial fibrillation patients that suffer repeated strokes, dementia can develop. In 2010, researchers at the Intermountain Medical Center Heart Institute initially linked atrial fibrillation to Alzheimers dementia. This study led to many others that have explored the complex relationship between Alzheimers disease and atrial fibrillation. In one study, Intermountain Medical Center Heart Institute researchers found that patients with erratic warfarin blood levels have significantly increased risk of dementia compared to those in which warfarin levels were stable and predictable. 

T. Jared Bunch, MD, a heart-rhythm specialist at the Intermountain Medical Center Heart Institute in Salt Lake City, and lead researcher of these studies, says that as we learn more about the association between atrial fibrillation and dementia we can begin to target ways to prevent it.

“We believe that one way in which atrial fibrillation increases risk of Alzheimers or idiopathic dementia is through small, but repetitive injuries to the brain from either microclots or bleeds," said Dr Bunch. "In patients with atrial fibrillation that are consistently underanticoagulated with warfarin there are higher rates of dementia, which suggests that small clots may be compromising brain function. At the same time, people that are consistently overanticoagulated with warfarin also have much higher rates of dementia, which suggests that small brain bleeds are also likely causes of brain injury.”

He added: “A natural question arises when you consider these studies involving warfarin, atrial fibrillation, and dementia, which is, if you use a predictable and stable anticoagulant for atrial fibrillation that does not fluctuate through interactions with diet, vitamins and supplements, and other drugs, will dementia rates improve?”

Researchers at the Intermountain Medical Center Heart Institute have found that three new blood thinners called direct oral anticoagulants on the market that offer an alternative to warfarin to prevent stroke and min stroke also lower risk of dementia.

Direct oral anticoagulants are similar to warfarin in that they prevent clot formation, however they work on a different area of the clot forming process. The clot effect is more precise and the elimination of the drugs is more predictable. They also have much fewer drug-related interactions that can cause a change in the blood effect compared to warfarin.

Half of the patient’s received (apixaban, dabigatran, or rivaroxaban) Eliquis, Pradaxa, or Xarelto and the other half of the patients received warfarin. The age of patients analyzed was between the ages of 62-82, with the average age being 72; 59 percent were male and 41 percent were female.

Over a median follow-up for 541 days since the first DOAC was available, new onset dementia and stroke rates were 51 percent less compared to warfarin. Overall patients treated with a DOAC were 15 percent less likely to die compared to those on warfarin largely due to a reduction in risk of dementia, stroke, and bleeding. 

“These study results show that DOACs are associated with lower dementia rates in our community," said Dr Bunch. "In people that have poorly controlled warfarin levels, DOACs may not only improve their risk of a major head bleed or stroke, they may also lower their risk of dementia. These study results also show that the results of clinical trials that led to the approval of the DOACs can also been achieved in a large community practice; specifically these drugs consistently lower rates of both stroke and bleeding compared to warfarin. Finally, these data give additional evidence that the association between atrial fibrillation and Alzheimers and other forms of dementia is from small and repetitive clots and bleeds in the brain that ultimately effect cognition”.

Members of this study include Victoria Jacobs, Heidi T. May, Tami L. Blair, Jeffrey L. Anderson, Brian G. Crandall, Mmichael Cutler, John D. Day, Charles Mallender, Jeffrey S. Osborn, Scott M. Stevens, J. Peter Weiss, Scott C. Woller, T. Jared Bunch.

The Intermountain Medical Center Heart Institute is the flagship facility for the Intermountain Healthcare system, based in Salt Lake City.