This study presents a novel metric to evaluate the heterogeneity of cardiac substrate by using vector maps derived from omnipolar electrograms. This metric determines the level of disorganisation of electrical propagation having the potential to classify cardiac tissue under the catheter. We tested the methodology on propagation maps obtained from experimental recordings with and without electrical stimulation, under the assumption that the former exhibit greater heterogeneity. Results show the discriminatory behaviour of the parameter (p < 0.001), assigning higher values to non-stimulated maps and lower values in cases with stimulation. The clinical relevance of this paper lies in the introduction of a new metric, derived from vector maps of omnipolar electrograms, which can classify cardiac tissue under the catheter based on the level of disorganisation of electrical propagation, providing electrophysiologists with valuable information for the management of arrhythmias.