Evaluation of Vein of Marshall Ethanol Infusion During Left Atrial Linear Ablation in Patients With Persistent Atrial Fibrillation

Inclusion Criteria: * Patients between the ages of 18 and 85 years * Diagnosed with symptomatic AF without previous mitral isthmus line ablation Exclusion Criteria: * Previous MI line ablation * Left atrial thrombus. LAA thrombus can be determined by preprocedural imaging: CT, TEE or MRI. * LA diameter greater than 55 mm on long axis parasternal view, or left atrial volume more than 200 cc. * Left ventricular ejection fraction \<35%. * Cardiac surgery within the previous 90 days. * Expecting cardiac transplantation or other cardiac surgery within 180 days. * Coronary PTCA/stenting within the previous 90 days or myocardial infarction within the previous 60 days. * Documented history of a thromboembolic event within the previous 90 days. * Diagnosed atrial myxoma. * Significant restrictive, constrictive, or chronic obstructive pulmonary disease with chronic symptoms. * Significant congenital anomaly or medical problem that in the opinion of the investigator would preclude enrollment * Women who are pregnant or who plan to become pregnant during the study. * Acute illness or active infection at time of index procedure * Renal insufficiency * Unstable angina. * History of blood clotting or bleeding abnormalities. * Contraindication to anticoagulation. * Life expectancy less than 1 year. * Uncontrolled heart failure. * Presence of a condition that precludes vascular access. * INR greater than 3.5 within 24 hours of procedure - for patients taking warfarin. * Patient cannot be removed from antiarrhythmic drugs for reasons other than AF. * Unwilling or unable to provide informed consent.