Time Course of Esophageal Lesions After Catheter Ablation with Cryothermal and Radiofrequency Ablation: Implication for Atrio‐Esophageal Fistula Formation After Catheter Ablation for Atrial Fibrillation

Background: Atrio‐esophageal fistulas have been described as a consequence of radiofrequency (RF) ablation for the treatment of atrial fibrillation (AF). However, whether cryoablation can avoid this potential fatal complication remains unclear. Methods and Results: We studied the effects of direct application of RF and cryoablation on the cervical esophagus in 16 calves. Cryoablation was performed with a 6.5‐mm catheter probe using a single 5‐minute freeze at <−80°C, and RF ablation was delivered with an 8‐mm catheter electrode at 50 W and 50°C for 45–60 seconds. Histopathologic assessments were performed at 1, 4, 7, and 14 day(s) after completion of the ablation protocol: four animals were examined each day. A total of 85 direct esophageal ablations were performed: 41 with RF and 44 with cryoablation. There were no significant differences in lesion width, depth, or volume between cryoablation and RF ablation at Day 1, 4, and 14 after the procedure (P > 0.05). However, lesion width and volume were significantly larger with RF than with cryoablation at Day 7. Although acute (Day 1) and chronic (Day 14) RF and cryoablation lesions were of comparable size, histologic evidence of partial‐ to full‐wall esophageal lesion ulceration was observed in 0 of 44 (0%) lesions with cryoablation, compared with 9 of 41 (22%) lesions with RF ablation (P = 0.0025). Conclusions: Direct application of cryoablation and RF ablation created similar acute and chronic lesion dimensions on the esophagus. However, cryoablation was associated with a significantly lower risk of esophageal ulceration, compared with RF ablation.