Oral Abstract Session: It’s Notall Aboutablation: Electrophysiological Insights Fromleftatrial Intervention

Purpose: Hybrid ablation (i.e. a combination of surgical thoracoscopic pulmonary vein (PV) isolation created using a box lesion on the posterior wall of left atrium followed by catheter ablation) has become a new technique for patients with persistent or long-lasting persistent atrial fibrillation (PeAF). However, EP findings following thoracoscopic ablation have not been described yet. Methods: Patients with PeAF were studied. Surgical ablation was carried out using unilateral thoracoscopic approach and a COBRA radiofrequency multipolar catheter. The aim of surgical ablation was to create a box lesion surrounding all four PVs. An EP study was done 1-3 months later to verify and complete box lesion on the posterior wall, and to perform right sided isthmus ablation. All patients were monitored for using 1-week Holter 1, 3 and 6 months after surgical ablation. Results: Eighteen patients with PeAF (age 59.8þ 10.4 years , 13 males, AF duration before ablation 27.8þ 23.8 months) were enrolled in the study. Surgical ablation was provided as described. An EP study was done 1-3 months later (mean duration was 222.8þ 59.3 min and fluoroscopic time was 21.4þ 7.0 min). The CARTO atrial volume measurement was 133.7þ 35.9. Box lesion completeness, based on the EP study, was in 7 (39%) patients. In the remaining 11 (61%) patients, the box lesion was incomplete. Completeness (using an RF ablation) was achieved in 9 of 11 patients (82%). Gaps were found in the superior line between the left and right superior pulmonary veins in 4 patients and anterior to the right or left superior pulmonary veins in the remaining 5 patients. In two patients, gaps were not localized due to multiples gaps or ongoing AF. The inferior line and the anterior parts of left and right inferior veins were completed in all patients. At the 6-month follow-up, AF free survival, without antiarrhythmic drugs, was present in 15 (83%) patients. Two patients developed atypical flutter with successful cardioversion and one patient sustained in AF. Conclusion: The hybrid approach in patients with PeAF was sucessful in most patients. The superior line and anterior parts of the right and left superior PVs were most likely to have conduction gaps following surgical ablation. CONGENITAL ATRIAL SEPTAL DEFECTAND ATRIAL FIBRILLATION: STAGED APPROACH IN COMPLEX ENDOVASCULAR TREATMENT