Radiofrequency and Cryoablation as Energy Sources in the Cox-Maze Procedure: a Meta-Analysis of Rhythm Outcomes

Abstract

Cox-maze IV is the most effective surgical procedure for atrial fibrillation (AF) treatment to date; however, few studies have compared the outcomes of the different energy sources applied to achieve transmurality. This study aimed to analyse the impact of the different energy sources on Cox-maze IV results in terms of sinus rhythm restoration. A systematic review and meta-analysis was conducted by including studies reporting rhythm outcomes on biatrial Cox-maze AF ablation with bipolar radio-frequency (BRF), cryoenergy (Cryo), or both (BRF+Cryo). The primary endpoints were the early and late rhythm outcomes of AF ablation using the different energy sources. Late AF recurrences were evaluated through timepoint analysis, and freedom from AF from Kaplan-derived data. Sixty articles including 8,293 patients were selected (3,364 patients Cryo, 1,937 BRF, and 2,992 BRF+Cryo). At 6 months, AF incidence was significantly lower in the Cryo group at 6.73%; it was 25.52% in the BRF and 16.79% in the BRF+Cryo groups (p=0.0112). At the 4-year timepoint, AF incidence was lower in the Cryo group compared with the BRF and BRF+Cryo: 6.14% vs 51.59% vs 16.09%, respectively (p=0.0392). Freedom from AF was 76.7%±2.2%, 60.9%±2.2%, and 66.3%±1.6% for Cryo, BRF, and BRF+Cryo at 4 years, respectively (p<0.001). At meta-regression, mean left atrial diameter was positively associated with higher AF recurrences (OR 1.04, 95% CI 1.01-1.08; p=0.0159). When performing this procedure, cryoablation seems to be associated with improved rhythm outcomes when compared with bipolar radiofrequency ablation.