Comparison of combined substrate-based mapping techniques to identify critical sites for ventricular tachycardia ablation

Abstract

Established electroanatomic mapping techniques for substrate mapping for ventricular tachycardia (VT) ablation includes voltage mapping, isochronal late activation mapping (ILAM), and fractionation mapping (FM). Omnipolar mapping (Abbott, Inc.) is a novel, optimized bipolar electrogram creation technique with integrated local conduction velocity annotation. The relative utilities of these mapping techniques are unknown. To evaluate the relative utility of various substrate mapping techniques for identification of critical sites for VT ablation. Electroanatomic substrate maps were created and retrospectively analyzed in 27 patients in whom 33 VT critical sites were identified. Both abnormal bipolar voltage and omnipolar voltage encompassed all critical sites and were observed over a median 66 (IQR: 41.3-86) cm2 and 52 (IQR 37.7-65.5) cm2, respectively. ILAM deceleration was observed over a median 9 (IQR 5.0, 11.1) cm2 and encompassed 22 (67%) critical sites, while abnormal omnipolar conduction velocity (OCV, <1mm/ms) was observed over 10 (IQR 5.3-16.6) cm2 and identified 22(67%) of critical sites, and fractionation mapping was observed over a median 4 (IQR 1.5, 7.6) cm2 and encompassed 20 (61%) critical sites. Mapping yield was greatest for Fractionation + OCV (2.1 critical sites / cm2), and least for bipolar voltage mapping (0.5 critical sites / cm2). OCV identified 100% of the critical sites in areas with a local point density >50 points/ cm2. ILAM, fractionation and omnipolar conduction velocity mapping each identified distinct critical sites and provided a smaller area of interest than voltage mapping alone. Sensitivity of novel mapping modalities improved with greater local point density.