A comparison of three methodologies for the computation of V-index

Spatial heterogeneity of ventricular repolarization (SHVR) can be assessed from surface ECGs using the V-index. The purpose of this study was to compare three algorithms for its estimate (which, for conciseness, will be termed M0, M1 and M2 in here). In deriving the V-index, the T-wave is modelled as a linear combination of a waveform (dominant T wave, DTW) and its derivatives, through scalar lead factors. M0, M1 and M2 differ in: i) number of DTW derivatives (2 for M0 and M1, 5 for M2); ii) numerical (M0 and M1) or analytical approximation (M2) of the DTW; and iii) a common DTW shared (M1) across beats.