Lesion Visualization of Pulsed Field Ablation by MRI in an Expanded Series of PAF Patients Pierre Jais 1 , MD, Yosuke Natakatani 1 , MD, Frederic Sacher 1 , MD, Nadir Tafer 1 , MD, M. Hocini 1 , MD PhD, M. Haissaguerre 1 , MD PhD, T. Pambrun 1 , MD, M. Takigawa 1 , MD PhD, Nicolas Derval 1 , MD, Richard Brose 2 , MS, Eric Buck 2 , MS, Raju Viswanathan 2 , PhD, Hubert Cochet 1 , MD PhD 1 Le CHU de Bordeaux, Bordeaux Univ. & L’Institut de Rythmologie et Modéllation Cardiaque (LIRYC) IHU LIRYC ANR-10-IAHU-04, Equipex MUSIC ANR-11-EQPX-0030 Bordeaux, France, 2 FARAPULSE, Inc. INTRODUCTION • Non-thermal pulsed field ablation (PFA) is a modality that has demonstrated myocardial specificity and may prevent extracardiac ablation • Late gadolinium-enhanced (LGE) MRI scans can provide direct visualization of lesion extent, dimension and homogeneity • We report on an expanded series of LGE MRI scans taken within immediately after PFA procedures. Disclosures: PJ - Research Grant and Consultant. RB, RV, EB - Employee. YN, FS, NT, MHo, MHa, TP, MT, ND, HC -none. METHODS • 23 patients (5 F, 56±11 y) with paroxysmal AF were included and received CT or MRI scanning to gauge esophageal proximity • A five-spline 12F catheter inside a 13F deflectable sheath was positioned for ostial pulmonary vein isolation using a dedicated PFA waveform generator (FARAPULSE) • Measures to alter lesion placement based on the proximity of the esophagus and phrenic nerve were not taken • Within 2 hours of PFA ablation, LGE MRI scans were performed to characterize the PFA lesions and assess for extracardiac damage. RESULTS • 90/90 PVs, including left common PVs, were isolated following the ablation procedure • The average dwell time in the left atrium was 49.9±15.0 min, improving to 37.5±9.5 min in the most recent ten procedures • Total energy delivery time per patient was less than 60 seconds • LGE MRI was performed on 18 patients after the procedure • The shortest LA-esophagus distance was noted next to the inferior veins: LIPV (12), RIPV (4), and rarely to the LSPV (2) CONCLUSIONS PFA creates dense and homogeneous lesions around the PVs, with no involvement of the esophagus as demonstrated by acute LGE MRI in an expanded study of 18 patients. PRE-ABLATION CT Distance to Eso (mm) • In 17 patients, the esophagus was directly adjacent to PFA lesions, measuring from 0.5 to 2 mm (1.2±0.5 mm) • No esophageal lesion was present in any patient • No visible discontinuities suggestive of lesion heterogeneity were observed in any PV • Myocardial lesions were present in the area of the phrenic nerve in all RPVs but no clinical effects were seen despite consistent phrenic capture during deliveries. POST-ABLATION LGE POST-ABLATION LGE Transverse Sagittal Spared Esophagus Eso LA