D. Sustained AF will be mapped and ablated FIRM maps of ongoing AF will be created and analyzed using RhythmView (Topera, Menlo Park, CA). Rotors and focal impulses are considered AF sources only if stable in repeated samples, to distinguish from transient fibrillatory activity. The focal source origin or rotor core (center of rotational activity) will be located by its electrode coordinates and localized digitally within each patient-specific anatomic shell at the time of each FIRM map to eliminate errors from subsequent possible movement.