Dementia Rises in Atrial Fibrillation Patients Treated With Warfarin, Study Finds

Problems worsened as time in the therapeutic range fell

A new study of more than 10,000 patients treated long-term with the blood thinner warfarin reveals higher rates of dementia for patients with atrial fibrillation (AF) versus patients without the common heart rhythm disorder.

The study by researchers at the Intermountain Medical Center Heart Institute found that patients with AF who were treated long-term with warfarin had higher rates of dementia, Alzheimer’s disease, and vascular dementia compared with anticoagulated non-AF patients.  Results of the research were presented by the Intermountain team on May 5 at Heart Rhythm 2016, the Heart Rhythm Society’s 37th Annual Scientific Sessions in San Francisco.

AF is is the most common type of arrhythmia, which is a problem with the rate or rhythm of the heartbeat. During an arrhythmia, the heart can beat too fast, too slow, or with an irregular rhythm. Incidence rates of AF are growing dramatically as the population ages. Dementia, a neurological disorder that impairs memory and other cognitive abilities, is now listed among the leading causes of morbidity and mortality in developed countries.

AF can increase the risk of dementia because it exposes patients to both large and small clots that can affect brain function. Blood thinners used to prevent all forms of clots and strokes can increase the risk of both large and small brain bleeds that can also negatively impact brain function over time.

The study was conducted through the Intermountain Healthcare Clinical Pharmacist Anticoagulation Service, which is part of the Intermountain Healthcare system based in Salt Lake City.

Researchers enrolled 10,537 patients with no history of dementia prior to the study. They were treated with a blood thinner for AF and non-AF conditions such as valvular heart disease and thromboembolism on a long-term basis.

Other variables in the patients studied included age, hypertension, diabetes, hyperlipidemia, renal failure, smoking history, prior myocardial infarction or cerebral vascular accident, and heart failure. Participants were aged 18 years and older.

During a follow-up of approximately seven years, researchers found that all types of dementia increased in the AF group more than the non-AF group.  In both groups, however, the risk of dementia increased as the time in therapeutic range decreased or became more erratic. When warfarin levels were consistently too high or too low, dementia rates increased regardless of why patients were receiving a blood thinner.

Researchers discovered that regardless of the adequacy of anticoagulation, AF patients consistently experienced higher rates of all forms of dementia. This finding indicates that the efficacy of therapy is strongly associated with dementia. Of note, researchers found that patients younger than 70 years tended to be the most susceptible to the risk of dementia.

“Our study results are the first to show that there are significant cognitive risk factors for patients treated with warfarin over a long period of time regardless of the indication for anticoagulation,” said lead author T. Jared Bunch, MD, director of heart rhythm research at Intermountain Medical Center Heart Institute and medical director for heart rhythm services for the Intermountain Healthcare system.

Source : Intermountain Health; May 5, 2016.