Termination of perioperative atrial fibrillation with epicardial cooling in the oblique sinus: A first-in-human feasibility study.

Background: Postoperative atrial fibrillation (AF) is associated with prolonged hospitalization, stroke and expense. We have previously demonstrated the effectiveness of cooling the oblique sinus to terminate AF in animal models. Objective: The study sought to determine whether cooling can terminate intraoperative AF in humans undergoing cardiac surgery. Methods: Patients presenting for clinically indicated cardiac surgery with a history of atrial fibrillation were enrolled. During surgery, before bypass, AF was induced if not present, and a 1 × 1 inch cooling device was placed in the oblique sinus that cooled to 5 to 10 °C at the device-tissue interface. Due to the pandemic, remote, real-time monitoring was used. Results: Four patients (all women, mean age 69.3 years) underwent 8 AF inductions. Five (63%) of 8 episodes were terminated with cooling, with average time to termination (after 30 seconds of sustained arrhythmia) of 21 seconds. Of the 3 failed episodes, 1 may have been a type II termination, 1 organized to flutter, and 1 failed to cool for technical reasons. There were no procedure-related complications. Conclusion: Termination of perioperative atrial fibrillation with epicardial cooling in the oblique sinus is feasible and appears safe in this very early first-in-human study.