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Brain Lesions and Cognition in Atrial Fibrillation Patients
Study Questions:
What are the relationships between cognitive function and vascular brain lesions in patients with atrial fibrillation (AF)?
Methods:
The investigators enrolled patients with known AF in a multicenter study in Switzerland, the Swiss-AF cohort study. Brain magnetic resonance imaging (MRI) and cognitive testing using the Montreal Cognitive Assessment (MoCA) were performed in all participants. Large noncortical or cortical infarcts (LNCCIs), small noncortical infarcts (SNCIs), microbleeds, and white matter lesions were quantified by a central core laboratory. Clinically silent infarcts were defined as infarcts on brain MRI in patients without a clinical history of stroke or transient ischemic attack (TIA). To assess the associations of vascular brain lesion parameters with MoCA score values and to adjust for potential confounders, the authors constructed linear mixed-effects regression models in which study center was included as a random intercept to account for potential differences across study centers.
Results:
The study included 1,737 patients with a mean age of 73 ± 8 years (28% women, 90% taking oral anticoagulant agents). On MRI, LNCCIs were found in 387 patients (22%), SNCIs in 368 (21%), microbleeds in 372 (22%), and white matter lesions in 1,715 (99%). Clinically silent infarcts among the 1,390 patients without a history of stroke or TIA were found in 201 patients with LNCCIs (15%) and 245 patients with SNCIs (18%). The MoCA score was 24.7 ± 3.3 in patients with and 25.8 ± 2.9 in those without LNCCIs on brain MRI (p < 0.001). The difference in MoCA score remained similar when only clinically silent LNCCIs were considered (24.9 ± 3.1 vs. 25.8 ± 2.9; p < 0.001). In a multivariable regression model including all vascular brain lesion parameters, LNCCI volume was the strongest predictor of a reduced MoCA (β = -0.26; 95% confidence interval, -0.40 to -0.13; p < 0.001).
Conclusions:
The authors concluded that patients with AF have a high burden of LNCCIs and other brain lesions on systematic brain MRI screening, and most of these lesions are clinically silent.
Perspective:
This study reports a high burden of vascular brain lesions on systematic brain MRI screening among well-treated patients with AF. Furthermore, the presence of overt or silent LNCCIs on MRI have a similar impact on cognitive function as overt strokes, suggesting that these lesions may explain at least part of the increased risk of cognitive dysfunction in these patients. The current analysis raises the concern that anticoagulation may not be sufficient to prevent a significant number of silent infarcts, especially those caused by mechanisms other than cardiac embolism. Additional studies are needed to evaluate whether patients with AF may benefit from brain MRI screening and to define optimal antithrombotic treatment to prevent silent infarcts in patients with AF.
Clinical Topics: Anticoagulation Management, Arrhythmias and Clinical EP, Geriatric Cardiology, Noninvasive Imaging, Prevention, Anticoagulation Management and Atrial Fibrillation, Implantable Devices, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias, Magnetic Resonance Imaging
Keywords: Anticoagulants, Arrhythmias, Cardiac, Atrial Fibrillation, Brain Infarction, Cognition, Embolism, Geriatrics, Hemorrhage, Ischemic Attack, Transient, Magnetic Resonance Imaging, Secondary Prevention, Stroke, Vascular Diseases
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