Area Available for Atrial Fibrillation to Propagate Is an Important Determinant of Recurrence After Ablation.

Abstract

This study sought to evaluate atrial fibrillation (AF) ablation outcomes based on scar patterns and contiguous area available for AF wavefronts to propagate. The relevance of ablation scar pattern acting as a barrier for electrical propagation in recurrence after catheter ablation for persistent AF is unknown. Three-month post-ablation atrial cardiac magnetic resonance was used to determine post-ablation scar. The left atrium (LA) was divided into 5 areas based on anatomical landmarks and scar patterns. The length of gaps in scar on the area boundaries was used to calculate fibrillatory areas (FAs) by adding the weighted contribution of adjacent areas. Cylindrical as well as patient-specific computational models were used to further confirm findings. A total of 75 patients that underwent an initial ablation for AF with 2 years of follow-up were included. The average maximum FA was 7,896 ± 1,988mm2 in patients with recurrence (n=40) and 6,559 ± 1,784mm2 in patients without recurrence (n=35) (p<0.008). After redo ablation in 19 patients with recurrence, average maximum FA was 7,807 ± 1,392mm2 in 9 patients with recurrence and 5,030 ± 1,765mm2 in 10 without recurrence (p<0.007). LA volume and total scar were not significant predictors of recurrence after the first ablation. In the cylindrical model, AF self-terminated after reducing the FAs. In the patient-specific models, simulation matched the clinical outcomes with larger FAs associated with post-ablation arrhythmia recurrences. This data provides mechanistic insights into AF recurrence, suggesting that post-ablation scar pattern dividing the atria into smaller regions is an important and better predictor than LA volume and total scar, with improvedlong-term outcomes in persistent AF.