Isolating the posterior left atrium and pulmonary veins with a Box lesion set: Use of epicardial ablation to complete electrical isolation

Epi-Endo Box Lesion for AF. Similar to the surgical mini-maze procedure, the posterior box lesion set employs linear ablation lesions along the anterior aspects of both sets of PVs connected by a roof line and an inferior line to electrically isolate the PVs and complete posterior LA wall en masse. However, creating fully transmural linear atrial lesions can be difficult to achieve, even with an irrigated ablation catheter. This report details a case wherein a combined endocardial and epicardial approach was required to create an electrically continuous posterior box lesion in a patient with persistent AF.