780 Mapping and ablation of recurrent arrhythmias after MAZE III surgery for lone atrial fibrillation

Abstract

Purpose: Maze III surgery for lone paroxysmal atrial fibrillation (PAF) shows freedom of arrhythmias in over 80% of patients. The mechanisms of late recurrences of arrhythmias are unclear. Methods: 11 of 139 pts who underwent classical MAZE III surgery were evaluated by electrophysiological study (EPS) for arrhythmia recurrence. Multipolar catheters in both atria were used to induce and map tachycardia. LocaLisaTM or NavXTM were used for 3-D mapping of the atrial anatomy and activation. RFCA was performed with a standard 4-mm RF catheter. Results: During ECG follow-up after MAZE III surgery, continuous atrial ectopy was seen in 1 pt, atypical flutter (FL) was present in 2, PAF in 5, typical FL and PAF in 1, AVNRT in 1 and AVNRT with PAF in the remaining pt. In 4 pts EPS showed persisting conduction from the pulmonary vein (PV) button to the remaining atrium. Conduction over the mitral isthmus (MI) persisted in 5, and over the tricuspid isthmus (TI) in 2 pts. The surgical lines were thus incomplete in a total of 7 pts. Three pts with an incomplete PV button line had PAF and PV potentials, and a successful ostial RFCA isolation of all 4 PVs was performed. One pt with an incomplete TI line had typical FL, successfully treated with RFCA of the isthmus. This pt also had PAF, but a remaining left atrial focus could not be abolished. One pt with an incomplete MI line had atypical FL, but RFCA failed to close the isthmus gap. In the remaining 6 pts, incomplete surgery did not correlate with arrhythmias. After successful RFCA of AVNRT in 2 pts, atrial arrhythmias persisted in one. In the pt with atrial ectopy, a septal focus could not be ablated. In the remaining 3 pts, atypical FL, ectopy or PAF were also found to be focal, in one of them possibly due to an epicardial remnant of surgical material. In only 1 pt RFCA could abolish a right septal focus. So far, 7 pts have become asymptomatic after successful RFCA. Conclusion: Arrhythmia recurrence after classical MAZE III surgery is related to incomplete surgical lines around the PVs and AV annulus, or focal atrial activation. Localization and ablation of surgical gaps and focal arrhythmias in these postoperative atria remains difficult despite sophisticated mapping.