Ventricular tachycardia signals are induced in a living subject. Pace-mapped signals are then obtained from multiple points within the ventricle, and automatically compared numerically with the induced signals. Recognition of a high degree of cross correlation between the induced signals and one or more of the pace-mapped signals identifies arrhythmogenic foci or pathways, which may then be ablated, so that the arrhythmia becomes non-inducible.