Vein of Marshall (VoM) ethanol ablation has a proven benefit in patients with persistent atrial fibrillation (AF) undergoing index procedure; however, its role in repeat ablation is unknown. We sought to evaluate the benefit of empiric VoM ethanol ablation in addition to posterior wall isolation (PWI) during the repeat procedure in patients with durable pulmonary vein (PV) isolation from prior ablation. Twenty-three patients (age 67.1 + / - 7.4, 74% males) who received empiric VoM ethanol infusion in addition to PWI were matched for age, gender, ejection fraction, and left atrial size with forty-six patients receiving empiric PWI alone. All patients in the study group underwent additional ablation on mitral isthmus to complete the lateral mitral isthmus line. Additional ablation was based on program and trigger stimulation. Primary outcome was freedom from AF after a blanking period of 3months by qualification of symptoms, EKG, wearable, or implantable monitor or device. The study group had a higher average BMI (35.07 + / - 8.98 vs. 30.85 + / - 5.65, p = 0.033) and rate of persistent AF (83.0% vs. 54.3%, p = 0.029) versus the control. The 1-year AF-free survival for the study and control groups was 20 (86.96%) and 28 (60.1%) patients (p = 0.027). Cox proportional hazard regression analysis showed a significant reduction in AF recurrence in the study group (HR 0.25, 95% CI 0.073-0.843, p = 0.026). Among patients undergoing repeat catheter ablation for recurrent AF with durably isolated PVs, the addition of VoM ethanol infusion increased the likelihood of remaining free from AF at 12months.