B-AB17-04 ELECTROPHYSIOLOGICAL FINDINGS IN PATIENTS UNDERGOING LEFT ATRIAL APPENDAGE OCCLUSION FOLLOWING PREVIOUS ELECTRICAL ISOLATION

Abstract Funding Acknowledgements Type of funding sources: None. Background Left atrial appendage electrical isolation (LAA) is an important adjunctive ablation strategy in patients with nonparoxysmal atrial fibrillation. If impaired mechanical function following isolation is observed, long-term oral anticoagulation (OAC) or, as an alternative, LAA occlusion are required. Although focal electrical potentials from the LAA do not result in normalization of appendage mechanical function, they may potentially be a source of arrhythmogenic triggers. Those focal areas might be challenging to ablate after LAA occlusion device implantation. Purpose We sought to report the incidence of focal electrical potentials in patients with a previously isolated LAA and transesophageal echocardiography (TEE) evidence of severely impaired LAA mechanical function undergoing endocardial LAA occlusion. Methods In 124 patients undergoing LAA occlusion following LAA isolation, a circular mapping catheter (CMC) was used before occlusion to document any residual LAA electrical activity. Results At preprocedural TEE, the median LAA contraction velocity was 0.13 m/s (IQR: 0.05-0.19) and was significantly impaired in all patients. Of the 124 patients (mean age: 69±8 years; 71.7% males), 61 (49.2%) did not display any evidence of residual LAA electrical activity. In the remaining 63 (50.8%) patients, residual electrical potentials resulting in LAA reconnection were recorded on the CMC positioned into the appendage. On average, 4.9±1.7 radiofrequency energy applications (45W, mean duration of each RFA: 14.2±3.4s) were required to re-achieve complete isolation. Subsequent appendage occlusion was successful in all patients. No leaks ≥5mm and 3 (2.4%) 3-4mm-leaks were documented at 45day-TEE. Conclusions Focal electrical activity from the LAA was documented in approximately half of our patients. Although focal electrical potentials do not result in normalization of LAA mechanical function, they may potentially act as arrhythmogenic triggers. Since it may be challenging after device implantation, assessment and ablation of those areas should be considered before occlusion device deployment.