Which Energy Source Is Superior? Bipolar Radiofrequency versus Cryoablation in Concomitant Atrial Fibrillation Surgery

Introduction: Concomitant surgical ablation is an established procedure for patients with atrial fibrillation (AF) undergoing cardiac surgery. Different energy sources are available to perform surgical ablation. At the moment, there is no clear evidence of which energy source is superior. We therefore compared bipolar radiofrequency (RF) with cryoablation in concomitant AF surgery.

Methods: Between 2003 and 2015, 642 patients underwent concomitant surgical AF ablation in our institution. A total of 123 patients were treated with cryoablation and 247 patients were ablated with bipolar RF and were included in this retrospective data analysis, rhythm monitoring by either 24-hour Holter ECG (n = 251) or implantable loop recorder (n = 119). Logistic regression analysis was used to identify predictors for rhythm outcome. Primary end point of the study was freedom from AF at 12 months follow-up.

Results: Patients treated with cryoablation were significantly younger compared with bipolar RF (69.4 ± 8.1 vs. 73.5 ± 8.6; p < 0.001), and both groups consisted of predominantly male patients (69.9 vs. 74.8%; p = 0.325). Paroxysmal AF was present in 48.8% of the cryoablation group and 41% of the RF group. There were no major ablation-related complications and no intraoperative death. Survival at 12 months was 92.5 and 91.1% in both groups; p = 0.649.

Freedom from AF did not differ significantly between cryoablation and RF at 3, 6, and 12 months (45.4 vs. 48.3%; 44.2 vs. 49.2%; and 64.0 vs. 60.7%). During 12 months follow-up, cardioversion was performed significantly more often in the RF group (16.4 vs. 5.8%; p = 0.004). In cryoablation group, logistic regression analysis showed simultaneous double valve procedures (p = 0.05; odds ratio [OR]: 0.063) and longer duration of AF (p = 0.039; OR: 0.845) as negative predictors. In the RF group, positive predictors for freedom from AF at 12 months were paroxysmal AF (p = 0.002; OR: 2.591) and coronary artery disease (p = 0.035; OR: 1.936); negative predictors were age (p = 0.001; OR: 0.933) and permanent AF (p = 0.003; OR: 0.419).

Conclusion: Bipolar RF as well as cryoablation is effective energy sources, resulting in good and comparable rates of freedom from AF at 12 months. In bipolar RF, cardioversion was more often necessary during follow-up. Predictors for freedom from AF are shorter duration of AF (cryoablation), paroxysmal AF, and a younger age (RF).

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