Abstract 12090: Catheter Ablation Impairs Left Atrial Function in Patients With Atrial Fibrillation: A Magnetic Resonance Imaging Study

Abstract

Introduction: Atrial fibrillation (AF) is associated with left atrial (LA) fibrosis and morphological remodeling. Catheter ablation (CA) is a well-established method of treatment for AF which results in additional LA scarring. Cardiac magnetic resonance (CMR) imaging is the gold standard for evaluating LA volumes and function, and feature tracking in CMR has been increasingly confirmed as a feasible and reproducible technique for assessing LA function through strain. We used CMR to assess baseline fibrosis, ablation-induced scarring and the impact of CA on LA volume, shape and function in patients with AF undergoing their first catheter ablation. Methods: AF patients underwent late gadolinium enhancement CMR prior to, then at least 3 months after CA for quantification of LA volumes, fibrosis and ablation-induced scarring, respectively (Panel A). Global longitudinal reservoir strain (GLRS) was assessed by feature tracking (Panel B). Cine-images were used to assess sphericity and emptying fraction. All CMR images were obtained in sinus rhythm. Wilcoxon signed rank analysis was used to assess the effect of CA on LA volume and sphericity index, emptying fraction and GLRS. Results: 40 patients (57% male, average age 61.9 years, 72.5% paroxysmal AF) were included. Pre-ablation LA fibrosis was 16.6% [9.1, 20.7] whereas ablation-induced LA scar was 8.0% [6.5, 12.1]. GLRS and LA emptying fraction decreased after CA (17.8 [15.3, 20.5] vs 16.0 [13.5, 19.0] p=0.006, and 60.2% [51.3, 66.4] vs 51.6% [46.3, 61.1], p<0.001, respectively). However, LA volume index and sphericity index were unchanged after CA in our study cohort (48.0 mL/m 2 [37.1, 61.1] vs 47.0 mL/m 2 [36.2, 52.7] p=0.91 and 54.6% [47.2, 65.4] vs 53.2% [46.5, 64.5] p=0.8, respectively) (Panel C). Conclusion: LA function is negatively impacted by catheter ablation for AF. The competing impact of ablation on rhythm control and atrial function with respect to stroke and heart failure need to be further evaluated.