Epicardial RFA to Achieve Electrical PV Isolation. During catheter ablation of atrial fibrillation, ablation within the pulmonary veins is undesirable due to the risk of pulmonary venous stenosis and the possibility of leaving residual cuffs of arrhythmogenic tissue proximal to the ablation lesion set. An extra-ostial pulmonary vein isolation strategy may circumvent these limitations, but achieving electrical isolation can be technically challenging, even with the use of saline-irrigated radiofrequency energy technology. This report describes the successful use of epicardial radiofrequency ablation in a patient in whom endocardial irrigated radiofrequency ablation failed to achieve extra-ostial pulmonary vein isolation.