ECGi Ibutilide: Effect of Ibutilide on AF Source Location and Organization

Inclusion Criteria: * ≥ 18 years of age. * ° Symptomatic persistent AF refractory or intolerant to at least 1 class I or III antiarrhythmic medication Persistent AF - defined as Persistent: AF that is sustained \> 7 days. Episodes of AF which are terminated by electrical or pharmacologic cardioversion after ≥ 48 hours of AF, but prior to 7 days, should also be classified as persistent AF episodes. * Planned to undergo first catheter ablation procedure ( prior atrial flutter typical is allowed) * Ability to understand the requirements of the study and sign the informed consent form. * Willingness to adhere to study restrictions and comply with all post-procedural follow-up requirements * Projected lifespan greater than 1 year Exclusion Criteria: * They have baseline prolonged QT or renal failure precluding safe used of ibutilide * Rheumatic heart disease, * Current intra-cardiac thrombus, * History of MI or CABG within 6 weeks; * Class IV HF, * Unable to sign consent * Projected lifespan of \< 1 year * Women known to be pregnant or to have positive beta-HCG. * Participation in another study that would interfere with this study. * Unstable Angina * Recent cerebral ischemic events * Contraindication to anticoagulation * Prior history of polymorphic ventricular tachycardia or torsades de pointes