Epicardium‐Based Left Atrial Ablation:

UNLABELLED: Epicardium-Based LA Ablation. INTRODUCTION: An important developmental task for surgical ablation of atrial fibrillation is simplification. A significant step would be the development of tools that create satisfactory ablation lesions without necessitating cardiopulmonary bypass or atriotomy. Optimally, these lesions would have no adverse impact on atrial electromechanical properties. METHODS AND RESULTS: We sought to characterize left atrial (LA) lesions created by a bipolar ablation device without cardiopulmonary bypass or atriotomy and to assess their impact on LA electromechanical properties. In each of five pigs, lesions were delivered to the epicardium of the beating heart, and encircled and connected right and left pulmonary vein vestibules and the atrial appendage. Before and after ablation, LA electromechanical properties were assessed using endocardial electromechanical mapping and intracardiac echocardiography. Postmortem histologic analysis also was performed. Each lesion was thrombus-free and barotrauma-free, histologically transmural, and a complete conduction barrier. Although a large aggregate area (24% +/- 6%) of LA myocardium was excluded, there was no significant change in global electromechanical properties. However, marked diminishment in appendage function was observed. CONCLUSION: Epicardium-based LA ablation in a beating heart could be achieved successfully without cardiopulmonary bypass or atriotomy. Although there was no adverse impact on global electromechanical properties, there was evidence of important regional diminishment.