Brain magnetic resonance imaging and cognitive alterations after ablation in patients with atrial fibrillation

概要

Introduction
Atrial fibrillation (AF) is associated with an increased risk of dementia even in patients without a history of stroke. Several mechanisms have been proposed to explain the association between cognitive impairment and AF, including microembolism, cerebral microbleeds (MBs). chronic cerebral hypoperfusion and brain atrophy. Catheter ablation is an important non・ pharmacological intervention for AF, but its effect on the incidence of asymptomatic cerebral emboli and long-term effects on cognitive function remain unknown.

Objectives
We aimed to evaluate whether catheter ablation has a protective effect on cognitive function by evaluating the incidence of cerebral microembolism as well as the neuropsychological outcome after catheter ablation in patients with AF.

Methods
We prospectively enrolled 101 patients who underwent AF ablation. Brain magnetic resonance imaging (MRI) (72 patients) and neuropsychological assessments (66 patients) were performed 1-3 days (baseline) and 6 months after ablation. Cardiac function was assessed by measuring ejection fraction (EF), left atrial volume index (LA VI) and brain natriuretic peptide (BNP) before ablation and at 3-6 months after ablation.

Results
Immediately after ablation, diffusion・weighted MRI and 3・dimensional double inversion recovery (3D・DIR) detected embolic microinfarctions in 63 patients (87.5%) and 62 patients (86.1 %), respectively. Most lesions were located in cerebral cortex. After 6 months, DIR lesions disappeared in 41 patients. Microbleeds (MBs) increased by 17%, and 65% of the de novo MBs were exactly at the same location as the microinfarctions. Average Mini・Mental State E xammat10n . scores improved from 27.9士 2.4to 28.5土 1.7(p = 0.037), and detailed neuropsychological assessment scores showed improvement in memory, constructional, and frontal lobe functions. EF, LAVI and BNP level improved from baseline to 3—6 months after ablation. Positive correlation was observed between the improvement of several neuropsychological scores and the improvement of cardiac function.

Consideration
Our study indicated that ablation has beneficial effects on overall neuropsychological scores despite the incidental embolic microinfarctions. Catheter ablation may suppress the chronic incidence of microembolism in AF, which may have a beneficial effect on cognitive dys釦nction. However, because small vessel diseases, including CMI, usually contribute to frontal lobe dysfunction, this possibility could not explain the improvement of neuropsychological scores encompassing overall cognitive domains in the present study. This result may indicate that improvement of cardiac output and subsequent CBF might have led to the recovery of neuropsychological scores in patients with AF.

Conclusion
Despite incidental microemboli, cognitive function was preserved 6 months after ablation.