Atrial Fibrillation is Associated with Cognitive Impairment in Patients with Heart Failure

Analysis of health records and questionnaire results from 881 heart failure patients indicates a significant link between permanent atrial fibrillation (AF) and cognitive impairment among such patients.

Investigators administered the Mini-Mental State Examination test to 876 of the patients and the Pfeiffer's Short Portable Mental Status Questionnaire to 848 of them and looked for patients who scored below 24 on the first test or made more than 2 errors on the second test.

Overall, 295 of the patients (33.5%) exhibited some degree of cognitive impairment and 45 (5.1%) exhibited moderate-to-severe cognitive impairment. Patients with permanent AF were more likely than others to exhibit any degree of cognitive impairment (43% vs. 31%) and moderate-to-severe cognitive impairment (8% vs. 5%).

Multivariate analysis indicated that cognitive impairment was independently and significantly associated with permanent atrial fibrillation (odds ratio, 1.54; 95% confidence interval [CI], 1.05 to 2.28). Other factors that were significantly associated with cognitive impairment included older age, female gender, diabetes mellitus, chronic kidney disease, previous stroke, New York Heart Association class III/IV status, and lower systolic blood pressure.

The mean age of the study population was 77 years ± 11 years. Members were 44% female and 48% of them had preserved ejection fraction.

“The presence of permanent AF is independently associated with cognitive impairment in patients with heart failure, both with reduced and preserved ejection fraction,” the investigators wrote in The American Journal of Cardiology. “Given the clinical impact of cognitive impairment in the heart failure population, active assessment of cognitive function is particularly warranted in patients with heart failure and with permanent AF.”

Many prior studies have linked AF and cognitive impairment (or an elevated risk of developing cognitive impairment) in many other patient populations.

The association stems, in part, from obvious causes. AF leads to strokes, which often lead to cognitive impairment. It probably goes deeper than that, however. Several studies have found that even AF patients who never suffer a stroke still experience unusual rates of cognitive decline.

Discovering the true size of the relationship between the two conditions has been difficult because they share so many risk factors: age, hypertension, diabetes, cardiac failure and, of course, stroke. A meta-analysis published 3 years ago in the Annals of Internal Medicine used data from 21 studies to estimate that AF was associated with higher risk for developing cognitive impairment in patients with or without a history of stroke (relative risk [RR], 1.40; 95% CI, 1.19 to 1.64).

To test reliability of this estimate, the authors of that study then restricted their analysis to prospective studies and obtained similar results (RR, 1.36; 95% CI, 1.12 to 1.65). They then looked only at studies of dementia and, again, obtained a similar estimate of the association between incident AF and the increased risk of later cognitive impairment (RR, 1.38; 95% CI, 1.22 to 1.56).

Efforts to discover why AF may help spur cognitive impairment in some patients have found a wide range of explanations, including the ablations that many AF patients undergo. Oral anticoagulants, moreover, 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.