Randomized Trial of Concomitant Maze Procedure Using Nitrous Oxide- Versus Argon-Based Cryoablation

Background: Currently, two types of cryoprobes are available: nitrous oxide (N₂O)-based and argon gas-based. However, few studies have compared the outcomes obtained with these two cryoprobe types. The aim of this study was to compare the early outcomes of a concomitant maze procedure using N₂O-based cryoablation (the N₂O group) versus argon gas-based cryoablation (the argon group) in patients with persistent atrial fibrillation (AF).

Methods: This study was a single-center, prospective, randomized controlled clinical trial. Sixty patients were randomly assigned to receive a concomitant maze procedure using N₂O-based cryoablation (n = 30) or argon gas-based cryoablation (n = 30) for persistent AF. Patients were followed up at 3, 6, and 12 months by electrocardiography, 24-hour Holter monitoring, and transthoracic echocardiography.

Results: No important intergroup differences were observed in terms of preoperative variables, morbidity, or mortality. During 1 year of follow-up, normal sinus rhythm was maintained in 26 patients in the N₂O group and 26 patients in the argon group (86.7% versus 86.7%, p = 1.000). Freedom from atrial arrhythmia events at 12 months was observed in 84.5% ± 4.7% without intergroup differences. Early AF episode before discharge was correlated with atrial arrhythmia events during follow-up (hazard ratio 7.89, 95% confidence interval: 1.75 to 35, p = 0.007). The N₂O group showed earlier recovery of left atrial activity compared with the argon group (p = 0.043); however, this difference disappeared after 6 months.

Conclusions: Both procedures have similar 1-year sinus rhythm maintenance rates. Left atrial contractile activity tends to return earlier in the N₂O group.