Abstract 4144382: Covering or Encircling the Fibrotic Substrate in the Left Atrium: Does it Matter? Insights from DECAAF II

Background: Left atrial fibrosis has been shown to be associated with atrial fibrillation (AF) recurrence after pulmonary vein isolation (PVI). The optimal way to target atrial fibrosis has not been determined still. Purpose: The aim of this study is to determine whether left atrial fibrosis, as detected by late gadolinium enhancement MRI (LGE-MRI), should be covered, encircled, or both, in addition to PVI, to improve ablation success in patients with persistent AF. Methods: We conducted an analysis of DECAAF II participants who were randomized to the PVI plus MRI-guided atrial fibrosis ablation arm. These patients underwent late-gadolinium enhancement MRI (LGE-MRI) before and after AF ablation. Left atrial ablation lesions were collected from intra-procedural electro-anatomical maps and were superposed on 3D left atrial MRI images of fibrosis. We divided the patients into three groups based on whether atrial fibrosis was covered, encircled, or both. After ablation, patients were instructed to provide single-lead smartphone-based ECG strips once daily and following symptoms based on which AF burden and recurrence after ablation was assessed. Uni- and multivariable regression models were developed to assess the association of the technique used with time-to-atrial arrhythmia recurrence. Results: 393 patients were included in our analyses. At baseline, patients were similar in comorbidity burden, age, sex, and left atrial volume. However, baseline fibrosis was different amongst the groups (19% vs 18% vs 20%; p-value=0.02). LA volume decrease was higher when atrial fibrosis was both encircled and covered simultaneously (31 mm3 vs 21 mm<span style="font-size:10.8333px">3</span> vs 23 mm<span style="font-size:10.8333px">3</span>; p= 0.006). The primary outcome of atrial arrhythmia recurrence was similar among all the groups as shown in figure A (p=0.17). Even after controlling for possible confounders such as age, body mass index, sex, comorbidities, left atrial volume index, and baseline fibrosis, the technique used to target atrial fibrosis was not associated with recurrence (p=0.07). Moreover, AF burden in the follow-up period was not different across the patient groups as shown in figure B (p=0.63). Conclusion: Among patients with persistent AF, neither covering nor encircling atrial fibrosis in addition to PVI affected atrial arrhythmia recurrence after catheter ablation. More studies should be done to optimize atrial fibrosis targeting and modification.