Inclusion Criteria:

• Patients must be at least 21 years old at the time of enrollment.
• Patients must be able to give informed consent.
• Patients with symptomatic paroxysmal/persistent atrial fibrillation (AF).
• Eligible patients must be determined to be suitable candidates for ablation to treat AF by their cardiologist and/or electrophysiologists regardless of this protocol.
• Patients are scheduled to have a pre-procedure cardiac CT upon the discretion of their electrophysiologists

Exclusion Criteria:

• Known allergy to iodinated contrast media.
• Elevated serum creatinine (> 1.5mg/dl) OR calculated creatinine clearance of < 60 ml/min (using the Cockcroft-Gault formula).
• Patients with a positive urine or serum pregnancy test will be excluded from this study.
• Patients with heart transplantation.
• Patients with polymorphic ventricular tachycardia (VT) or presenting in electrical storm.
• Presence of any other history or condition that the investigator feels would be problematic.
• Patient with iodinated contrast administration for other reason 24 hours prior to investigational CT.
• Patients who have a heart pacemaker, metallic foreign body (metal sliver) in their eye, or who have an aneurysm clip in their brain, mechanical heart valves and prosthetics that contain metal.
• Patients with severe claustrophobia.