B-PO02-135 LEFT VENTRICLE POSTERIOR SUPERIOR PROCESS ECTOPY: RISK OF AV NODE BLOCK DURING ABLATION

Abstract

Premature ventricular contractions (PVC) originating from the highest portion of the inferior left ventricular (LV) septum are infrequent and challenging to treat with catheter ablation (CA). The incidence and CA risks are ill-defined. We sought to determine the incidence of PVC originating from the posterior superior process (PSP) at our institution. We reviewed our records retrospectively between 1/2018 and 10/2020 for all PVC ablations. We selected all patients who underwent PVC ablation from the PSP region. 370 patients underwent PVC were identified from institutional ventricular tachycardia database. Of the total cohort, four patients (1%) had PVCs ablated from the PSP region. Three of four were male, normal LVEF average 51% and only one had myocardial scarring on imaging studies. Despite different PVC morphologies, EKG had common characteristics including monophasic R in lead I, rS in lead II and slow downsloping QS in aVR (the “RI-rSII-QSaVR” triad). Acutely successful ablation was performed in all four cases. In all but one case, RF ablation at the earliest mapping site was associated with either transient delay in AV conduction or accelerated junctional rhythm. In 6 months follow up, none of the patients had arrhythmia recurrence. Prolonged monitoring in two patients indicated high degree AV block at sleep but none meet the criteria for pacing. PVCs originating from the PSP are rare, occurring in about 1% of referred patients. Even when approached from the left side, attention to proximity to the compact AV node is warranted when ablating in the PSP region. Despite these concerns, success of ablation is high.