PLAI-AF Trial: Hybrid Endo-epicardial Partial Left Atrial Isolation vs. Endocardial Ablation in Patients With Persistent Atrial Fibrillation

In patients with symptomatic atrial fibrillation (AF), current clinical guidelines recommend ablation for rhythm control. While percutaneous ablation has good results in patients with paroxysmal AF, it is not clear which is the best technique in patients with persistent or long-standing persistent AF. Our group performed the first randomized study of thoracoscopic epicardial ablation vs. endocardial catheter ablation (FAST Trial), which showed better results for epicardial ablation but with a higher rate of complications. Hybrid epicardial and endocardial ablation strategies have recently been described sequentially, showing better results in patients with persistent AF, but 40% of patients are still refractory to ablation. Our study aims to compare the conventional strategy (catheter ablation) with partial electrical isolation of the left atrium endo-epicardially (pulmonary veins, posterior wall and left atrial appendage) in a single procedure in the group of patients most refractory to ablation. Likewise, using magnetic resonance imaging and echocardiography to analyze the atrial remodeling factors that can predict the success and failure of both therapies. Methodology: A 1:1 randomized clinical trial in patients with persistent and long-standing persistent AF in two groups: conventional ablation vs. partial endo-epicardial isolation. Prior to ablation, cardioversion will be performed and functionality and atrial size will be verified by echocardiography, delayed-enhancement / 4D flow magnetic resonance imaging (MRI), andelectrocardiographic imaging (ECGi) will detect the degree of fibrosis and atrial remodeling. During the ablation procedure, a continuous rhythm recording device will be implanted. Likewise, at three months the MRI will be repeated to detect post-ablation fibrosis. At six months the echocardiography will be performed to assess atrial function and size. AF recurence will be assessed using an internal loop recorder within a 1-year follow-up. Main Expected Results: The expected results include: 1. an improvement in the rate of patients with no atrial arrhythmias recurrence in patients undergoing endo-epicardial ablation; 2. a lower AF burden in patients undergoing endo-epicardial ablation who have had recurrence; 3. To know the degree of atrial remodeling (including atrial fibrosis) associated with the success/failure of each technique; 4. To know the degree of fibrosis that both techniques produce; 5. To know the degree of ventricular function associated with the success/failure of each technique; 6. To know the degree of potentially lost atrial function; 7. To Compare the safety of both techniques