REDUÇÃO DO METABOLISMO CEREBRAL REGIONAL EM PACIENTES COM FIBRILAÇÃO ATRIAL SEM ACIDENTE VASCULAR CEREBRAL: Insights de um estudo FDG-PET

Abstract

Background and aims Atrial Fibrillation (AF) is an independent risk factor for incident dementia. Cerebral hypoperfusion related to beat-to-beat blood flow variation during AF can explain the occurrence of dementia or mild cognitive impairment in stroke-free AF patients. However, brain metabolism patterns in this scenario are still uncertain. We aimed to investigate brain metabolism patterns in stroke-free AF patients under optimal oral anticoagulation treatment. Methods Ten patients with long-standing persistent/permanent AF underwent brain FDG-PET imaging. Images from patients, controls without AF or dementia (n=28), and Alzheimer Disease (AD) patients (n=28), were compared. Cognitive questionnaires were applied. 24h-Holter and Echocardiogram were also performed. Exclusion criteria: paroxysmal AF, presence of permanent pacemaker, previous diagnosis of stroke or dementia, hemodynamically relevant carotid stenosis, moderate/severe aortic valve stenosis, psychiatric disorder, decompensated diabetes, previous neurosurgery, alcoholism, or presence of left ventricular systolic dysfunction. FDG-PET images were compared using statistical parametric mapping to assess regional brain metabolism differences between the groups. Results The study group median age was 64, 70% male. The median CHA2DS2VASC score was 1 and 90% of the patients were taking oral anticoagulants. All patients had normal ejection fractions (median 65%) and well controlled heart rate on Holter (mean 75bpm). Fronto-temporal cerebral hypometabolism was observed in study patients compared to controls. This hypometabolism pattern was distinct from AD patients’ pattern, which was more pronounced in components of the limbic system. Conclusion AF patients present a specific pattern of brain hypometabolism, independent of the occurrence of thromboembolic phenomena and distinct from the AD pattern.