Atrial Fibrillation in Stroke-Free Patients Is Associated With Memory Impairment and Hippocampal Atrophy

Author(s): Knecht S, Oelschlager C, Duning T, et al.

Citation: Eur Heart J 2008;Jul 29:[Epub ahead of print].

Clinical Trial: No

Study Question: Does atrial fibrillation (AF) cause cognitive impairment independent of stroke?

Methods: Detailed neuropsychological testing and brain magnetic resonance imaging (MRI) were performed in 112 patients with AF (mean age 60 years, paroxysmal AF in 54%) and 563 age-matched controls (mean age 64 years). Patients with prior stroke were excluded. In the AF group, 52% of patients were treated with warfarin and 23% with a platelet inhibitor. The association between AF and cognitive impairment was assessed by multivariate analysis that included other vascular risk factors such as hypertension, smoking, and diabetes.

Results: AF was independently associated with a small but statistically significant decrease in learning, memory, attention, and executive functions. There was no significant difference in cognitive scores between patients with paroxysmal and persistent AF. Hippocampal volume by MRI was approximately 8% smaller in patients with AF. AF was not associated with any change in total brain volume.

Conclusions: AF is associated with cognitive impairment and shrinkage of the hippocampus independent of stroke and other vascular risk factors.

Perspective: Shrinkage of the hippocampus, which is highly sensitive to vascular injury, provides a structural basis for the cognitive impairment associated with AF. Aside from stroke, AF is associated with microembolization, platelet dysfunction, and endothelial dysfunction, and one or more of these factors could account for injury to the hippocampus. The decreases in cognitive performance were relatively small in magnitude, raising some question as to whether the findings were clinically meaningful. Nevertheless, the results are noteworthy and suggest that AF may decrease cognitive reserve. This may explain why AF is associated with accelerated deterioration in patients with Alzheimer disease. Fred Morady, M.D., F.A.C.C.