Abstract 14906: Impact of Time Between Stacked Lesions During Radiofrequency Atrial Ablation With Active Esophageal Cooling

Abstract

Background: Active esophageal cooling during radiofrequency (RF) ablation of the left atrium (LA) has been shown to reduce esophageal injury. Although no atrioesophageal fistula has been reported in over 12 thousand uses to date, the first pericardio-esophageal fistula to occur despite cooling reinforces the fact that a threshold may exist at which heat extraction capacity may be surpassed. We aimed to examine this threshold by measuring the transmurality of esophageal injury after sequential lesion placement. Hypothesis: Reduced rest time between stacked lesions increases tissue lesion depth by enhancing thermal latency effects. Methods: Using a computational model of the left atrium, we determined esophageal lesion depth between sequentially placed RF lesions using high-power, short duration power settings (50 W for 10 s). Lesion depth was determined via Arrhenius equation, and anatomical dimensions were:1.5 mm for atrial myocardium, 0.75 mm for pericardial tissue, and 2 mm for the esophagus. Three lesions were placed on the myocardium with either 5 s or 10 s pauses in between. Final lesion transmurality was measured 45 s after the last placement to fully account for latent heating. Results: Active esophageal cooling reduced esophageal lesion transmurality by 80% after the first lesion. Sequential lesions increased esophageal lesion transmurality, with thermal latency contributing to increased lesion depth even after cessation of RF energy. Shorter timing between lesions allowed further growth in transmurality: 4% for 90 W, and 8.5% for 50 W power settings (Figure 1), showing that the efficacy of cooling against thermal latency effects decreased with the placement of each subsequent lesion. Conclusions: Active esophageal cooling reduces esophageal lesion transmurality by 80% when single lesions are placed. Stacking additional lesions at the same point reduces this safety benefit, with shorter intervals between lesions resulting in less protective effect.