Stefansdottir H, Arnar DO, Aspelund T, Sigurdsson S, Jonsdottir MK, Hjaltason H,et al. Atrial Fibrillation is Associated With Reduced Brain Volume and Cognitive Function Independent of Cerebral Infarcts. Stroke. 2013
Shruti Sonni, MD
This large study by Arnar et al. aimed to assess the association between atrial fibrillation (AF)and brain structure and cognition in an elderly population. Measurements obtained included brain volume, presence of infarcts on MRI and cognitive battery tests including memory, speed of processing and executive function. The results showed that patients with AF had lower total brain volume, total gray and white matter, and higher volume of white matter hyperintensities. This association was stronger with persistent or permanent AF and there was a trend with increased time since diagnosis, suggesting a cumulative negative effect of AF on the brain.
These findings may be explained by multiple microembolisms in AF causing microinfarcts and resulting atrophy, especially in the hippocampus. Another factor contributing is beat by beat variation in stroke volume, with previous studies suggesting cerebral perfusion is more affected in patients with persistent AF than paroxysmal AF. One of the drawbacks of this study was that the authors were unable to record the frequency and length of AF at enrollment, and hence were unable to fully assess the actual burden of AF. Future prospective studies need to determine the importance of maintaining sinus rhythm to prevent brain atrophy and cognitive decline, and these parameters should be considered as endpoints in future trials looking at outcomes in AF.