Abstract 2856: Remodeling of Left Atrial Scar and Closure of Gap Lesions Following Atrial Fibrillation Ablation: Assessment With Delayed Enhancement MRI at One-Year Post-Procedure
Background: Delayed-enhancement MRI (DE-MRI) can characterize left atrial (LA) scar and gap lesions following AF ablation, however little is known regarding how scar evolves over time.
Methods: Thirty-five patients underwent DE-MRI 3 and 12 months following AF ablation. Quantitative analysis of scar was obtained using a threshold-based algorithm to compare changes between the two time points. Qualitative analysis of 3D LA models was used to compare scar lesion location and size, as well as presence of gap lesions between 3 and 12 months. The extent of scar at 12 months was correlated with procedural outcome.
Results: The mean total LA wall scar at 3 months post-ablation was 15.1%±6.2% compared to 15.6%±6.8 % at 12 months, resulting in a mean scar change of 4.1%±17.0%. Twenty-three patients had progression of scar (+13.6%±11.8%) compared to 12 patients who had regression in scar (−14.1%±8.2%). Thirteen patients (37.1%) had extension of existent scar, with all regions expanding off of pre-existent scar zones. Six patients (17.1%) experienced closure of pockets of viable tissue, consolidating posterior wall scar. Three patients (8.6%) had extension of scar along the pulmonary veins closing pre-existent gap lesions. Patients with AF recurrence had less total LA wall scar (11.9%±4.9%) as compared to patients with successful procedure outcomes (17.4%±6.9% (p=0.024).
Conclusion: Scar remodeling post-AF ablation often results in expansion of lesions causing consolidation of posterior wall scar and closure of prior gap lesions. The extent of scar at 12 months post-ablation correlates with successful procedural outcomes.