Ischemic brain infarcts, white matter hyperintensities, and cognitive impairment are increased in patients with Atrial Fibrillation.

Background The interrelationships between atrial fibrillation (AF), brain lesions and cognitive function are poorly understood. We aimed to investigate the relationship of AF with brain lesions and cognition.Methods We enrolled 1,480 patients with and 959 without AF in a multicenter prospective study (Swiss-AF; NCT02105844). We assessed brain structure, and cognition using the Montreal Cognitive Assessment (MoCA). Brain magnetic resonance imaging (MRI) was performed to assess large non-cortical and cortical infarcts (LNCCI), small non-cortical infarcts (SNCI), white matter hyperintensities (WMH), and microbleeds. Using causal mediation analyses, we investigated the direct (lesion-independent) and indirect (lesion-mediated) effects of AF on cognition.Results Mean age in AF patients is 75.0 vs. 74.2 years in no-AF patients, 28.6% vs. 36.9% are female, and comorbidities are comparable. The prevalence of MRI-detected brain infarcts (LNCCI and/or SNCI) is 40.1% in AF patients vs. 24.0% in no-AF patients, adjusted OR (95% CI): 1.78 (1.30; 2.44), p = 0.0003. WMH (Fazekas ≥2) are more prevalent in AF patients (59.2% vs 44.4%), adjusted OR (95% CI): 2.03 (1.50; 2.77), p = 4.6e-06. The mean MoCA score is 25.3 in AF patients and 26.4 in no-AF patients. In mediation analysis, the total effect of AF on cognition is -1.05 MoCA points, decomposed into a direct effect of -0.99 and an indirect, lesion-mediated, effect of -0.06 points.Conclusions The prevalence of ischemic brain infarcts and WMH is higher in patients with AF than without AF despite comparable comorbidities. AF is associated with lower cognitive function, primarily through a direct effect rather than mediated by brain lesions.Atrial fibrillation is a common heart rhythm disorder in which there is an irregular heartbeat. It has been associated with damage to the brain and reduced cognitive function, which is the mental processes involved in thinking, learning, and processing information. However, the relationship is poorly understood. We assessed brain structure and cognitive function in people with similar characteristics that either had or did not have atrial fibrillation. We found that people with atrial fibrillation had more brain damage visible by brain imaging and lower cognitive function, compared to people without atrial fibrillation. The brain damage seen did not seem to be the main cause of the lower cognitive function. The main driver of lower cognitive function was most probably the arrhythmia itself.