Abstract
Left Atrial (LA) enlargement is prevalent amongst atrial fibrillation (AF) patients and constitutes an important marker of underlying atrial myopathy. Several studies have described reduction in LA volume following catheter ablation (CA) of AF, however, none have investigated differences in remodeling related to additional ablation outside of the pulmonary veins. We sought to compare early remodeling of the LA between patients who received pulmonary vein isolation (PVI) only, and those who received additional fibrosis-guided extra-PV ablation. This study was a retrospective analysis of the DECAAF II randomized controlled trial. Patients with persistent AF (perAF) were randomized to receive PVI only or PVI + fibrosis-guided ablation. Late Gadolinium Enhancement Magnetic Resonance Imaging (LGE-MRI) was performed before and three months after CA to measure LA volume. Only patients in sinus rhythm at both MRIs are included. Patients were followed up with single-lead ECG devices for 12-18 months. Arrhythmic burden was calculated as the percentage of ECGs exhibiting AF. Univariate and multivariate regression were used to identify predictors of LA volume change. This analysis included 206 patients who met our inclusion criteria. The mean LA volume before ablation was 114.6 ± 36.9 mm3, and the mean volume post-ablation was 101.2 ± 32.3 mm3, with a mean reduction of 13.5 ± 22.3 mm3 (9.92% reduction, p <0.001). Patients randomized to receive MRI-guided fibrosis ablation had more LA volume reduction than patients who were randomized to PVI only (17.03 ± 25.04 mm3 vs 10.17 ± 18.89 mm3, p=0.03). This association persisted with multivariate analysis where pre-ablation left ventricular ejection fraction (LVEF) and randomization to receive substrate modification were the only predictors of LA volume reduction (table). LA volume reduction was associated with greater improvement in LVEF, regardless of treatment randomization (r = 0.242, p = 0.01). LA volume reduction did not predict arrhythmia recurrence when considered as a continuous variable. We noted more pronounced LA volume reductions in patients randomized to receive PVI + fibrosis-guided ablation when compared to those randomized to receive PVI only. We hypothesize worsened left atrial relaxation and diastolic dysfunction as an etiology for this difference, but further study is needed to better characterize the important structural impacts of extra-PV ablation.
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