Effect of Cryothermic and Radiofrequency Cox-Maze IV Ablation on Atrial Size and Function Assessed by 3D Echocardiography, A Randomized Trial. To Freeze or to Burn

Abstract

Abstract BACKGROUND Cox-maze procedures are safe methods of restoring sinus rhythm (SR) in patients with atrial fibrillation (AF), and are often performed concomitant with mitral valve (MV) surgery. Atrial linear scars are achieved using Cryothermy (Cryo) or radiofrequency (RF) techniques. It is unclear how these energy sources differ in terms of effects on late left atrial (LA) reverse remodeling. We used 3-dimensional echocardiography (3DE) to compare the impact of Cryo and RFprocedures on LA size and function one year after Cox-maze IV ablation concomitant with MV surgery. METHODS Seventy-two patients with MV disease and AF were randomized to Cryo (n = 35) or RF (n = 37) ablation. Another 33 patients were enrolled according to the protocol without ablation (NoMaze). All patients underwent echocardiogram before and one year after surgery. Between-group differences were evaluated using the Student’s paired t-test. Fisher’s analysis was used for categorical data. RESULTS Forty-two ablated patients recovered sinus rhythm (SR) one year post-surgery, and had comparable left and right systolic ventricular function and a mean LA size reduction of 23% (LA volume index decreased from 66 ± 24 to 54 ± 13 ml/m2; p = 0.004). The 3DE extracted reservoir and booster function were higher after RF (37 ± 10% vs. 26 ± 6%; p < 0.001) than Cryo ablation (18 ± 9 vs. 7 ± 4%; p < 0.001), while passive conduit function was comparable between groups (24 ± 11 vs. 20 ± 8%; p = 0.17). Compared to maze groups, patients with restored SR without ablation (7 patients) had similar LA size reduction but more preserved systolic atrial function. The level of LAVI reduction depended on AF duration. Up to 30% reduction in 60% of patients with documented AF less than 6 months compared to 11% in those with AF for more than 5 years. CONCLUSIONS SR restoration after mitral surgery and maze resulted in LA size reduction, irrespective of the applied energy source. Using 3DE, we demonstrated that compared to RF, Cryo produced an extended ablation area that implies LA structural remodeling affecting LA systolic function. Reduced reverse size remodeling was associated with longer AF history. TRIAL REGISTRATION DOI 10.1186/ISRCTN14454361.