PO-01-166 OUTCOMES FROM REDO ABLATION OF PERSISTENT AF USING SPATIOTEMPORAL DISPERSION MAPPING IN AN INTERNATIONAL TWO CENTRE SERIES

Strategies for redo ablation of persistent atrial fibrillation are debated. This has led to emergence of additional ablation beyond the pulmonary veins targeting dynamically mapped mechanisms. Spatiotemporal dispersion is such a technique using stable electrograms spanning more than 75% of the cycle length over a multipolar catheter and has shown benefit in recent trials. We set out to study an international two centre series for clinical outcomes using this technique in redo ablations. We recruited consecutive patients between September 2018 to September 2021 undergoing redo ablation for persistent AF. Patients were all mapped using Pentaray to mark areas of spatio-temporal dispersion (STD) criteria before any ablation. After confirming pulmonary vein isolation, or re-isolation if connections were present, ablation of all STD areas was performed. Areas were remapped if the patient remained in AF, to prove impact of local ablation, including in the right atrium. If termination to AT occurred, this was mapped using conventional methods. Patients who terminated to sinus underwent reinduction pacing protocols to map any further AT or AF inducible. Patients were followed up at 12 months with 5-7 days continuous event monitor. In total 168 patients were studied at redo ablation for persistent AF (age 66, 68% male, LA diameter 4.8cm). They had undergone 1.4 procedures on average. Over 50% had isolated pulmonary veins at the start of the case. Termination of persistent AF to sinus rhythm (42%) or atrial flutter or tachycardia (41%) was obtained in 140 (83%). Mean procedure duration was 267 min, average number of STD sites in the LA was 2.7. The right atrium was mapped for STD sites in 79 (46%) of patients, and had 1.2 locations treated on average. At 12 months, freedom from AF or AT was 74% overall. Of the patients with recurrences, only 11 (7%) had AF, with 93% recurring with AT or AFL. Figure shows STD patterns (green arrows) on Pentarray in a 67 year old man inferior to left inferior pulmonary vein (A), where ablation terminated AF to sinus rhythm (B). In this two centre international series of redo persistent AF ablations, the use of STD mapping led to increased rates of acute termination and freedom from AF at 12 months. Clinical recurrences were most often organised atrial flutter or tachycardia. Our study informs the real world application of this technique to the more common scenario of additional clinical benefit when pulmonary veins are already isolated.