Catheter Ablation -> Atrial Fibrillation & Atrial Flutter: -> Ablation Techniques D-PO02 - Poster Session II (ID 47) Poster

D-PO02-161 - Contemporary Analysis Of Lateral Mitral Isthmus Line Ablation (ID 233)


Background: Ablation across the postero-lateral mitral isthmus (MI) is important in treating persistent AF and atypical atrial flutters. However, ablation in this area is challenged by variable tissue thickness, difficulty in maintaining catheter stability and epicardial convective cooling by the coronary sinus (CS). Approaches to deal with CS cooling include placing an air-filled balloon in the CS to displace the blood pool, and ablation from within the CS. Importantly, failure to achieve bidirectional block (BDB) is quite pro-arrhythmic.
Objective: To assess durability of the MI line in patients presenting for redo procedures where the first ablation had been performed using contemporary techniques.
Methods: Pts undergoing 2 ablation procedures for AF/AFL were collected between 2017-2019 from a single center. A retrospective review of the MI ablation details and outcomes was conducted.
Results: We included 53 pts who received a MI line and returned for a subsequent procedure. CS ablation was performed in 47 pts (89%) during initial ablation, and CS balloon occlusion had been employed in 15 (28%) pts. Ultimately, acute BDB was achieved in most pts (46 of 53, 87%). However, durable MI block occurred in only 18 of 53 (34%) pts at repeat study. CS balloon occlusion had no impact on durability (OR 0.39, 95% CI 0.09-1.64).
Conclusion: Mitral isthmus ablation is frequently acutely successful, but lesion durability is low upon repeat mapping despite employing air-filled CS balloons, and ablating from directly within the CS. This highlights the need for new techniques/technologies (eg, ethanol infusion into the Vein of Marshall, large thermal footprint ablation catheters, etc) for mitral ablation.