Incidence of Significant Delayed Esophageal Temperature Drop After Cryoballoon-Based Pulmonary Vein Isolation

Background: The second-generation cryoballoon (CB2) has demonstrated superior clinical outcome. Potential procedural complications include esophageal thermal lesions due to excessive esophageal temperature (ET). Safety cut-offs for the ET have previously been published. A safety margin was incorporated due to a delayed esophageal temperature decline even after termination of the CB2 freeze cycle. The extent of these delayed temperature drops requires further systematic evaluation. Methods and Results: The study enrolled 29 patients with paroxysmal or shortstanding persistent AF who underwent CB2-based PVI. Freeze cycle duration was 240 seconds. No bonus freeze was applied after successful PVI. The intraluminal ET was continuously measured via a transorally inserted probe (SensiTherm, St. Jude Medical, Inc.). The CB2 temperature and ET were recorded throughout the procedure using a camera setup. The mean number of freeze cycles per patient was 4.3 ± 2. A total of 147 cryoenergy applications were analyzed. A delayed decline in ET of >0.5 °C was recorded following termination of 23.1% of freeze cycles. The maximum drop in delayed ET was 6.4 °C. Excessive esophageal cooling during the freeze cycle exceeding 8.5 °C/min may result in ET ≤10 °C. Conclusions: Following termination of cryoenergy delivery, the ET may decline an additional 6.4 °C. Proposed ET safety cut-offs during CB2-based PVI need to account for a significant ET drop that may occur even after termination of the individual freeze cycle.