Differential remodeling of the left atrium and left atrial appendage in patients with very late recurrence of atrial fibrillation after catheter ablation

Abstract Background Patient and arrhythmia characteristics are important determinants of AF recurrence after catheter ablation of atrial fibrillation (AF). Left atrial (LA) remodelling and reduction in size after ablation is associated with improved outcomes. However, little has been described of the remodelling of the LA appendage (LAA) post ablation. Purpose To assess the LA and LAA remodelling in patients with very late recurrence (more than 5 years) of AF. Methods This was an observational study of AF ablation cases undertaken at 3 associated hospitals. Patients presenting for repeat ablation 5 years after initially successful AF ablation were included. We compared pre- and post-ablation LA and LAA volumes from pre-procedural CT scans. A three-dimensional image of LA and LAA were constructed using 3D Mapping System. The consequential LA and LAA volumes were measured using the reconstructed 3D maps. We excluded those without pre-procedural CT imaging or where quality of the scans showed inadequate contrast filling of the LA and LAA on both occasions. We also excluded those with LAA occluder device in situ. Results From the year 2006 up till 2024, a total of 139 consecutive patients underwent repeat catheter ablation very late after initially successful AF ablation, we included 58 patients (70% male) with the mean age of 72±9 years who had good quality CT scans with adequately filled LAA in both CT scans. The time difference between the first and second ablations were 10.6±3.4 years. The types of AF ablation done at index procedure is depicted in figure below. The left atrial volume had decreased from 104.1±28.2 cm3 before the index ablation to 90.7±24.7 cm3 before the repeat ablation (P=0.008). The left atrial appendage size has increased significantly from 9.0±3.9 cm3 at the index ablation to 12.1±5.8 cm3 before the repeat ablation (P=0.001). Conclusion There is evidence of differential remodeling of the LA and LAA chronically after catheter ablation of AF. This remodeling is associated with significant LAA volume expansion with the LA reducing in size. This increase in LAA size may have implications to LAA arrhythmogenesis and thrombogenesis. These changes may be a result of change in hemodynamic within the LA and LAA due to ablation. In addition, it may be an important marker of unrecognized or untreated factors that may have been responsible for the initiation and propagation of AF.