Photo courtesy of NIGMS
SAN FRANCISCO—Patients with atrial fibrillation (AF) who are on warfarin long-term have a higher risk of dementia than non-AF patients on long-term warfarin therapy, according to a new study.
The AF patients studied had higher rates of dementia, Alzheimer’s disease, and vascular dementia than their non-AF counterparts.
However, both groups of patients had a greater risk of dementia if they had lower percentages of time in therapeutic range (TTR).
“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 T. Jared Bunch, MD, of the Intermountain Medical Center Heart Institute in Salt Lake City, Utah.
Dr Bunch and his colleagues presented this research at the Heart Rhythm Society’s 37th Annual Scientific Sessions (abstract MP01-04).
The researchers enrolled 10,537 patients, age 18 and older, with no history of dementia prior to the study. They were receiving long-term warfarin for AF (n=4460), thromboembolism (n=5868), or mechanical heart valves (n=209).
The AF patients were older and had higher rates of hypertension, diabetes, heart failure, and stroke than the non-AF patients.
During a follow-up of approximately 7 years, the researchers found that all types of dementia increased in the AF group more than the non-AF group.
AF patients experienced higher rates of total dementia (5.8% vs 1.6%, P<0.0001), Alzheimer’s disease (2.8% vs 0.9%, P<0.0001), and vascular dementia (1.0% vs 0.2%, P<0.0001).
The researchers performed a propensity analysis of 6030 patients to account for the differences in baseline characteristics. And the risk of dementia remained significantly higher in AF patients than non-AF patients.
The hazard ratio (HR) was 2.42 for all types of dementia (P<0.0001), 2.04 for Alzheimer’s disease (P<0.0001), and 2.46 for senility (P<0.0001).
However, both AF and non-AF patients saw an increase in the risk of dementia if they had a low percent TTR.
In multivariate analysis, with the TTR >75% group as the reference, the HR for dementia in AF patients was:
- 1.30 for the 51%-75% TTR group (P=0.10)
- 1.57 for the 26%-50% TTR group (P=0.02)
- 1.92 for the ≤25% TTR group (P=0.005).
The HR for dementia in non-AF patients was:
- 1.57 for the 51%-75% TTR group (P=0.13)
- 2.69 for the 26%-50% TTR group (P=0.002)
- 3.87 for the ≤25% TTR group (P<0.0001).
Dr Bunch and his colleagues believe these findings have implications for treatment.
“First, as physicians, we have to understand that, although we need to use anticoagulants for many reasons, including to prevent stroke in AF patients, at that same time, there are risks that need to be considered, some of which we are only right now beginning to understand,” Dr Bunch said.
“In this regard, only those that absolutely need blood thinners should be placed on them long-term. Second, other medications like aspirin that may increase the blood thinner’s effect should be avoided unless there is a specific medical need. Finally, in people that are on warfarin in which the levels are erratic or difficult to control, switching to newer agents that are more predictable may lower risk.”
