Bronchial effects of cryoballoon ablation for atrial fibrillation

Background Damage to extracardiac structures, including the esophagus and phrenic nerve, is a known complication of cryoballoon ablation (CBA) during pulmonary vein (PV) isolation for atrial fibrillation (AF). Other adjacent structures, including the pulmonary bronchi and lung parenchyma, may be affected during CBA at the PV ostia. Objective The purpose of this study was to prospectively study the bronchial effects of CBA in humans undergoing CBA for PV isolation. Methods Ten patients undergoing CBA for AF under general anesthesia were enrolled in an institutional review board–approved prospective observational study. Real-time bronchoscopy was performed during cryoablation of PVs adjacent to pulmonary bronchi to monitor for thermal injury. Patients were followed for the development of respiratory complaints postprocedure. Results In 7 of 10 patients (70%) and in 13 of 22 freezes (59%), ice formation was visualized in the left mainstem bronchus during CBA in the left upper PV. Ice formation was not seen in the right mainstem bronchus during right upper PV CBA. The average time to ice formation was 89 seconds. There was no significant difference (P = −.45) in average minimum balloon temperature during freezes with ice formation (−48.5°C) and freezes without ice formation (−46.3°C). No patients went on to develop respiratory complications. Conclusion Unrecognized ice formation occurs frequently in the left mainstem bronchus during CBA for AF. This information helps explain the source of cough and hemoptysis in some patients who undergo CBA. The long-term consequences of this novel finding and the implications for procedural safety are unknown.