Abstract 14421: Limitations of Using Unipolar Signals to Guide Outflow Tract Premature Ventricular Contraction Ablation

Abstract

Introduction: Unipolar electrogram (EGM) signals are universally used to annotate earliest activation and guide ablation (Abl) of focal arrhythmias. However, their utility in mapping PVCs is limited given 3-dimensionality of wave front propagation, especially when the source is intramural. Hypothesis: 1) earliest onset of bipolar activation would better guide mapping and Abl in these cases, versus maximum unipolar dV/dt or QS morphology; and 2) differences would be greater for intramural outflow tract (OT) PVCs versus those eliminated with RVOT Abl only. Methods: Consecutive patients undergoing successful RVOT or RVOT+LVOT PVC Abl at our center from 2017-2020 were retrospectively analyzed. Bipolar and Unipolar EGMs at successful Abl sites were compared. Results: Of 71 patients, 41 had only RVOT and 30 had RVOT + LVOT Abl. All had acute and long-term PVC suppression over mean 22.6 ± 11.6 month follow-up. Mean EGM difference was 7.6 ± 4.7 ms in the RVOT group vs 18.9 ± 10.5 ms in RVOT+LVOT group (p<0.01). QS unipolar EGM was seen in 95% of RVOT patients, 88% of which were at the anterior RVOT/crux, vs 40% of RVOT+LVOT patients (p<0.016). Activation was equally earliest from the posteroseptal RVOT and adjacent LVOT site in 73%, and most of these sites did not have a QS unipolar EGM (Figure). Conclusions: Bipolar EGM activation timing guided successful ablation of OT PVCs better than unipolar EGM analysis. A QS unipolar EGM did not reliably predict best ablation sites, especially for intramural PVCs.