PO-03-142 ABLATION OF EPICARDIAL POSTEROSEPTAL ACCESSORY PATHWAYS IN CHILDREN

Abstract

Epicardial posteroseptal accessory pathways (Epi-PSAPs) within the coronary sinus (CS) are a rarely reported ablation target in children. They are often associated with abnormal CS anatomy as well as risk of coronary artery (CA) injury. To assess characteristics associated with successful outcome of Epi-PSAP ablation in children. Retrospective cohort study at a tertiary care institution including all patients aged ≤18 years who underwent ablation of Epi-PSAP from 2000-2022. Clinical/electrophysiological characteristics and outcomes were analyzed. Epi-PSAP was targeted in 19 patients. Mean age at procedure was 13.4 (12.1-14.7) years, mean weight was 62.5 (47-78) kg. Prior ablations had been attempted in 7/19 patients. Ventricular preexcitation was present in 12/19 (63%) patients, with steep negative delta wave in lead II in all cases, and 8/12 (67%) demonstrating high risk antegrade conduction. CS angiogram to define the anatomy was performed in all patients. In 5/5 (100%) of cases where CS diverticulum was identified by CS angiogram, it proved to be the ablation target. CA angiogram to define arterial proximity (5mm cutoff) was obtained in 17/19 (90%). CA system was right dominant in 10/17 (59%), and closest arteries were ≥5mm away from the target in 11/17 (65%). Primary energy was RF in 12/19 (63%, artery ≥5mm) and cryo in 7/19 (37%, artery <5mm). Ablation was acutely successful in 18/19 (95%) patients, chronically successful in 15/18 (83%) of patients, over 98.2 (57.8-138.7) months of follow up.There was no apparent difference in outcome between ablation sites in 1) coronary vein; 2) CS diverticulum; or 3) floor of CS (FIG1.A.). The presence of a sharp unipolar accessory pathway potential (FIG1.B.) at the target site was significantly associated with acute (p=0.003) and chronic (p=0.005) success. Choice of energy was not significantly associated with outcome. Performance of CS angiogram (FIG1.C) was significantly associated with acute (p=0.04) and chronic (p=0.03) success when all ablation attempts were analyzed. There was no incidence of major adverse events. Majority of Epi-PSAP in children are manifest with high risk antegrade conduction properties. They can be ablated with RF energy when the coronary arteries are ≥5mm from ablation target, or alternatively with cryoablation. Localizing a sharp unipolar AP potential, identification of CS anatomy by CS angiogram, and delineation of arterial proximity by CA angiogram are associated with successful ablation.