Freezing Equals Freezing? Performance of Two Cryoablation Devices in Concomitant Mitral Valve Repair

Background Recent guidelines have recommended the addition of ablation in cardiac surgery for patients presenting with atrial fibrillation (AF). Currently available cryoablation devices use either nitrous oxide or argon gas as cooling agent. Our study aimed to compare success rates of two different devices currently available on the market and applied during concomitant cardiac surgery. Methods Between 2009 and 2012, data were collected from 120 consecutive patients in whom either the aluminum cryoICE ablation probe (AtriCure, Inc., Cincinnati, Ohio, United States) using nitrous oxide or the stainless steel Cardioblate CryoFlexTM 10-S probe (Medtronic, Inc., Minneapolis, Minnesota, United States) using argon gas was applied for concomitant ablation procedures in minimally invasive mitral valve cases. Perioperative variables, myocardial injury biomarkers (MIBs) and Holter monitoring results were compared. Results Perioperative variables such as sex, age, type, and duration of AF, procedure and cross-clamp times, and 30-day mortality did not significantly differ between the groups. Postoperative peak creatinine kinase MB (CK-MB) levels were significantly higher in the nitrous oxide group (p = 0.047). At a mean follow-up of 20 ± 13 months, freedom from AF was significantly higher in the nitrous oxide group (87%) compared with the argon group (71%, p = 0.044). Left atrial (LA) diameter and device used were the only predictors of failure of ablation (p = 0.029 and p = 0.018, respectively). Conclusion The nitrous oxide-based aluminum probe revealed a better outcome than the argon-based stainless steel probe. Besides the cooling agent, probe material and probe-tissue interface might have contributed to the better performance of the cryoICE probe.