Can We Preserve Cognitive Function in Patients with Atrial Fibrillation?

Despite much evidence that atrial fibrillation (AF) greatly increases the risk of cognitive decline, a review of research to date finds little compelling support for any particular strategies to minimize that risk.

The new paper, which appears in the Journal of Atrial Fibrillation, concludes that the rapid increase in the total number of AF cases, along with the far greater cost of treating patients who are no longer capable of managing their own care, necessitates further research and concrete answers.

“As the prevalence of AF increases,” the authors write, “it is more imperative that we optimize our methods to preserve cognitive function.”

The association between AF and cognitive decline stems, in part, from obvious causes. AF leads to strokes, which often lead to cognitive impairment.

Yet the association may go deeper than that. Several studies suggest that even AF patients who never suffer a stroke still experience unusual rates of cognitive decline.

Researchers have struggled for many years to determine whether there truly is an independent relationship between AF and cognitive decline, in part because of the significant overlap in the known risk factors for both conditions: age, hypertension, diabetes, cardiac failure and, of course, stroke.

The first papers to conclude that such a link actually does exist came in the late 1990s, but a number of papers have followed since then. The largest project to find an independent tie, the Rotterdam study, used data from more than 6,500 patients.

Researchers have also found the association particularly strong among AF patients who are under 70 years old or those who have already progressed to the early stages of dementia when they are first diagnosed with AF.

Another factor that appears to increase the risk of cognitive decline is the use of various types of ablation to restore the heart to normal sinus rhythm. Indeed, ablation appears to increase the risk of cognitive decline in several ways.

“Catheter ablation itself is a potential iatrogenic source of clinical and sub-clinical brain embolism, with an incidence up to 22%,” write the authors of the research review, who all work at Asklepios-Klinik St. Georg, Dept. of Cardiology in Hamburg, Germany.

“In addition, introduction of air and thrombus embolism into the arterial system as well as charring on catheter electrodes can both contribute to cognitive decline, and this has been shown in several imaging studies that have demonstrated new MRI brain lesions that develop after AF ablation procedures.”

The use of oral anticoagulants‑‑be they traditional vitamin K antagonists or newer compounds such as dabigatran, rivaroxaban or apixaban‑‑can protect cognitive function by reducing ischemic strokes but they can also endanger the brain by increasing the risk of hemorrhagic strokes and brain micro-hemorrhages.

So how should clinicians balance considerations of mental health with those of maintaining proper heart rhythm and minimizing the danger of complications such as thromboembolism? The research to date can only offer general strategies.

AF, stroke and cognitive decline all “share similar risk factors, in particular modifiable risk factors such as hypertension, diabetes mellitus and chronic cardiac failure,” the study authors write.

“Moreover, other cardiovascular risk factors such as dyslipidemia and smoking play an important role in increasing the incidence of stroke itself. Therefore, an important aspect in the treatment of AF and the preservation of cognitive function is the management of these risk factors,” the authors stated.

Only more research, they write, can provide more specific strategies.