LAUSR

Abstract Funding Acknowledgements Type of funding sources: None. Background Left atrial flutter (LAFL) may have epicardial components not accessible to endocardial ablation by radiofrequency (RF) application. Subxiphoid access to the pericardial space has been reported in isolated cases. Purpose to prospectively evaluate the efficacy and safety of subxiphoid access to the pericardial space to map and ablate LAFL refractory to endocardial RF application. Methods Patients with LAFL confirmed by activation and entrainment mapping and refractory to endocardial RF application were consecutively enrolled. An epicardial component of the tachycardia circuit was suspected when parts of the AFL activation, channels of slow conduction or conduction gaps on previous ablation lines intersecting the AFL circuit were not found. Pericardial access was obtained by subxiphoid puncture performed conventionally or facilitated by saline infusion or CO2 insufflation into the pericardial space. Following pericardial access, epicardial mapping and ablation was performed with a conventional RF irrigated tip ablation catheter. All procedures were performed under oral anticoagulation and during following heparin infusion for 350 sec activation clotting time target. Results 15 patients with 18 LAFL were included (61.0 ± 8.8 years, 80% male). 14 patients have had a previous atrial fibrillation (AF) ablation. Epicardial ablation was attempted after a previous LAFL endocardial ablation procedure in 6 patients and during the same endocardial ablation procedure in the last 9 patients. Pericardial access was not achieved in 1 patient due to pericardial adhesions (after prior cardiac surgery). Ablation was successfully performed in 11 patients (73.33%) and failed in 4 patients with perimitral AFL (1 patient also had a peri-left appendage AFL). The successful ablation site was found in the transverse sinus of Theile over the Bachmann bundle in 14 patients with perimitral, septal and anterior-wall LAFL and in the oblique sinus in a posterior-wall LAFL. No patient presented relevant complications except for 2 patients who presented hemopericardium and 1 with delayed cardiac tamponade following accidental RV puncture and who required pericardiocentesis. No patient presented AFL recurrences at 19.8 months (range 6-34 months) follow-up except for 2 patients in whom ablation failed or pericardial access was not achieved. Conclusions Epicardial ablation of LAFL refractory to endocardial ablation is successful in most patients following successful pericardial access. This approach appears associated with low risk of significant complications. Endoepicardial Propagation Map Epicardial AFT Ablation (Theile sinus)