Procedures for ablation of persistent or long lasting atrial fibrillation are frequently long and require extensive ablation. Some electrophysiologists administer the drug ibutilide during these procedures to help organize the fibrillatory activity of the left atrium with the hope that this may shorten the length of the procedure and duration of ablation needed. Currently there is no standardized approach of administering the drug ibutilide during these procedures, thus the investigators cannot be certain that administering this drug does in fact facilitate the procedure. The aim of the MAGIC-AF Trial is to see if administering a standard dose of the drug ibutilide at a standard time in the procedure can allow for a reduction in the ablation procedure time. The investigators hypothesize that administering ibutilide during these procedures will result in a reduction in the procedure and ablation time required.

Definition: Patients with persistent atrial fibrillation will be enrolled in this trial. All patients will be required to be in atrial fibrillation on the day of the procedure. Standard pulmonary vein (PV) isolation will be performed. Patients will be enrolled in the trial if they remain in atrial fibrillation after bi-directional block is obtained in the left and right sided PVs. At this point, patients will be randomized to receive 0.25mg of IV ibutilide or a placebo (normal saline). Patients will then undergo additional ablation with areas of complex fractionate electrograms (CFE) being targeted. The duration of additional CFE ablation and use of additional non-PV ablation (i.e. placement of linear lesions) will be left to the discretion of the operator. Patients will be followed for 1 year. The primary outcome assessed will be freedom from AF at 1 year.

Inclusion Criteria:

• Males and females will be enrolled in the study.
• Age >18
• Referred for a first ever ablation procedure for symptomatic persistent/permanent AF (only prior ablation of right-sided typical flutter is permitted)
• All patients must understand the requirements of the study and be willing to comply with the post study follow-up requirements.
• Patients must be in atrial fibrillation on the day of the procedure

Exclusion Criteria:

• Any reversible cause of AF (post-surgery, thyroid disorder, etc.)
• Patients with a myocardial infarction or unstable angina in the previous 2 months.
• Patients with a history of rheumatic heart disease
• Patients with congenital heart disease
• Patients with a history of hypertrophic cardiomyopathy
• Patients with LV ejection fraction < 35%
• Class IV congestive heart failure
• Patients who have experienced any cerebral ischemic event, including any TIA in the preceding 1 month.
• Women who are known to be pregnant or have had a positive β-HCG test 7 days prior to procedure.
• Patients with any other significant uncontrolled or unstable medical condition (including uncontrolled clinically significant coagulation disorders).
• Patients whose life expectancy is less than one year.
• History of malignant ventricular arrhythmias or long QT interval (>500msec)
• Prior left-sided cardiac ablation procedure (catheter based or surgical)
• Mental impairment precluding the patient from providing informed consent or completing the appropriate follow up