Multi-modal magnetic resonance imaging to assess cerebrovascular function in patients with atrial fibrillation

Atrial fibrillation (AF) is associated with a high risk of stroke, as well as cognitive decline and dementia. Advanced imaging techniques were employed to test the hypothesis that AF worsens cerebrovascular function as evaluated using neurovascular coupling (NVC) and cerebrovascular carbon dioxide reactivity (CVR_CO2) tests. Twenty healthy controls (HC; 63.4 ± 9.5 years) and 19 AF patients (66.6 ± 12.0 years) completed NVC (visual stimulation with a flickering checkerboard) and CVR_CO2 (5%CO₂) assessments during functional (blood oxygen level-dependent [BOLD]) and perfusion (arterial spin labelling) magnetic resonance imaging. Additionally, brain volumes and cognition were assessed. During CVR_CO2 assessment, neither %∆ in BOLD signal (HC: 3.09 ± 0.50; AF: 3.23 ± 0.70%; p = 0.513) nor %∆ in cerebral blood flow (CBF) (HC: 36.6 ± 18.8; AF: 43.6 ± 20.6%; p = 0.319) were different between groups. During NVC assessment, CMRO₂ (HC: 5.25 ± 1.84; AF: 4.36 ± 2.50%, p = 0.285), %∆BOLD (HC: 1.60 ± 0.38; AF: 1.66 ± 0.79%; p = 0.762) and %∆CBF (HC: 49.4 [20.1-71.9]; AF: 51.7 [38.3-66.9]%; p = 0.850) all increased similarly in HC and AF. AF patients had lower hippocampal volume relative to total intracranial volume than HC (0.50 ± 0.06 vs 0.55 ± 0.06%; p = 0.020). There were no differences between HC and AF in cognitive performance across multiple domains (all p > 0.05). These results suggest that NVC and CVR_CO2 responses are preserved in AF.