Image-based computational evaluation of the competing effect of atrial wall thickness and fibrosis on re-entrant drivers for atrial arrhythmias

Abstract

Catheter ablation is a common treatment for atrial fibrillation (AF), but long-term patient outcomes remain suboptimal. Knowledge of the location of re-entrant drivers (RDs) sustaining AF can help optimize ablation strategies for individual patients. Increasing evidence suggest that both fibrosis and atrial wall thickness (AWT) can influence the RDs dynamics. This study aims to analyse the role of fibrotic patches and AWT in determining RD sites in human right (RA) and left (LA) atrial models. Atrial geometries and fibrosis distribution were obtained from 2 healthy volunteers and 2 AF patients using MR imaging. These 4 subject-specific geometries were integrated into 3D atrial models with the Fenton-Karma model adopted to reproduce atrial electrophysiology. In the RA model without fibrosis, RDs anchored to the crista terminalis (CT) if initiated near a prominent AWT gradient between this bundle and surrounding RA. In the presence of fibrosis, RDs either pinned between the CT and fibrotic patch or anchored to the latter, depending on the distance from their initiation site to the CT. In the LA model without fibrosis, RDs drifted towards the thinner pulmonary veins. However, with fibrotic patches added, RDs either anchored around them or broke down into multiple wavelets. These findings can help identify RD locations from imaging data and guide ablation therapy.