Abstract 10771: Avoidance of Lethal Isotherm Formation in Esophageal Tissue with an Active Cooling Device Under High-Power, Short-Duration Ablation

Introduction: Atrioesophageal fistula (AEF) is a severe complication of left atrial ablation for the treatment of atrial fibrillation. Thermal injury is the proposed mechanism, and a potential pathway occurs through exceeding the lethal isotherm of esophageal tissue in contact with the left atrial posterior wall. Active cooling with a novel cooling device has been shown to significantly reduce thermal injury, with no AEFs encountered after more than 4200 treatments worldwide. We aimed to evaluate the effects of active cooling when specifically using newer high-power short-duration (HPSD) ablation settings to further estimate the protective mechanisms of this novel approach to reduce serious injury. Hypothesis: Active cooling may preclude attainment of a lethal isotherm in esophageal tissue under HPSD ablation. Methods: We developed a model of the left atrium and esophagus, and simulated radiofrequency (RF) ablation of the left atrium under HPSD settings. Tissue thickness was set to typical posterior-wall parameters (Figure). Power settings were evaluated at 50 W for 10 seconds, and 90 W for 4 seconds. Active cooling was set to a typical 4 °C coolant temperature. Lethal isotherm temperature was taken as 50 °C. Results: In both scenarios of HPSD ablation, the peak esophageal mucosal temperature reached 39° C in control conditions, using no active cooling. With active cooling in place, peak temperatures remained below 11 °C (Figure). Peak temperatures at the epi-esophageal region of esophageal tissue exceeded the lethal isotherm of 50 °C in control conditions, but remained at or below the lethal isotherm with active cooling in place. Conclusions: Based on our mathematical modeling, esophageal cooling significantly reduced temperature rise and prevented the achievement of temperatures thought to be lethal to esophageal tissue. This finding may offer a mechanistic rationale for the absence of serious esophageal injury encountered to date using this approach.