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Objective: Expert consensus guidelines recommend surgical ablation (SA) for patients with symptomatic atrial fibrillation (AF), but less than half of patients with AF undergoing cardiac procedures receive concomitant SA. Complete isolation of the left atrial posterior wall (LAPW) has been shown to be the most critical part of the Cox maze procedure. The purpose of this study was to investigate the performance of a novel radiofrequency (RF) bipolar device, EnCompass™ (AtriCure, Inc., Mason, OH, USA), designed to isolate the LAPW in a single application. Methods: Five adult pigs underwent SA in a beating heart model. After a single ablation, the heart was arrested, explanted, and stained with triphenyl-tetrazolium-chloride for histological assessment. Each lesion was sectioned, and the ablation depth, muscle, and fat thickness were determined. The lesion width, energy delivery, and ablation times were compared with those from a reference RF clamp (Synergy™, AtriCure). Results: Transmurality was documented in 100% of lesions (5 of 5) and cross sections (160 of 160). Electrical isolation was documented in every instance. There was no evidence of clot, charring, or pulmonary vein stenosis. Compared with the reference clamp, the lesions created by the EnCompass™ clamp were 1.5 times wider on average. The average energy delivered was 5 times higher over a duration that was 4.5 times longer due to the increased volume of tissue ablated. Conclusions: The EnCompass™ clamp reproducibly created transmural isolation of the LAPW with a single application. This may allow for simplification of the SA strategy and increased adoption of AF treatment during concomitant surgery.

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