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

BACKGROUND Established electroanatomic mapping techniques for substrate mapping for ventricular tachycardia (VT) ablation in-cludes voltage mapping, isochronal late activation mapping (ILAM), and fractionation mapping. Omnipolar mapping (Abbott Medical, Inc.) is a novel optimized bipolar electrogram creation technique with integrated local conduction velocity annotation. The relative utilities of these mapping techniques are unknown.OBJECTIVE The purpose of this study was to evaluate the relative utility of various substrate mapping techniques for the identifica-tion of critical sites for VT ablation.METHODS Electroanatomic substrate maps were created and retro-spectively analyzed in 27 patients in whom 33 VT critical sites were identified.RESULTS Both abnormal bipolar voltage and omnipolar voltage en-compassed all critical sites and were observed over a median of 66 cm2 (interquartile range [IQR] 41.3-86 cm2) and 52 cm2 (IQR 37.7- 65.5 cm2), respectively. ILAM deceleration zones were observed over a median of 9 cm2 (IQR 5.0-11.1 cm2) and encompassed 22 critical sites (67%), while abnormal omnipolar conduction velocity (CV <1 mm/ms) was observed over 10 cm2 (IQR 5.3-16.6 cm2) and identified 22 critical sites (67%), and fractionation mapping was observed over a median of 4 cm2 (IQR 1.5-7.6 cm2) and encom-passed 20 critical sites (61%). The mapping yield was the highest for fractionation 1 CV (2.1 critical sites/cm2) and least for bipolar voltage mapping (0.5 critical sites/cm2). CV identified 100% of crit-ical sites in areas with a local point density of .50 points/cm2.CONCLUSION ILAM, fractionation, and CV mapping each identified distinct critical sites and provided a smaller area of interest than did voltage mapping alone. The sensitivity of novel mapping modalities improved with greater local point density.

Automated summary

This study evaluated the relative utility of different substrate mapping techniques for VT ablation. ILAM, fractionation, and CV mapping each identified distinct critical sites and provided a smaller area of interest than did voltage mapping alone. The sensitivity of novel mapping modalities improved with greater local point density.