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

Established electroanatomic mapping techniques for substrate mapping for ventricular tachycardia (VT) ablation includes 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.

The purpose of this study was to evaluate the relative utility of various substrate mapping techniques for the 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 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 encompassed 20 critical sites (61%). The mapping yield was the highest for fractionation + CV (2.1 critical sites/cm²) and least for bipolar voltage mapping (0.5 critical sites/cm²). CV identified 100% of critical sites in areas with a local point density of >50 points/cm².

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.