BACKGROUND: High density electroanatomical mapping (EAM) is the standard for identifying functional substrate in scar-related ventricular tachycardia (VT), but it is limited by its two-dimensional nature and increased procedural complexity. Imaging-based strategies provide anatomical characterization but lack functional information. We evaluated a novel digital twin model (CardioMat) to non-invasively predict functional substrate in three-dimensions. OBJECTIVE: To validate a novel digital twin model for noninvasive prediction of functional substrate in scar-related ventricular tachycardia. METHODS: Fifteen patients with ischemic or nonischemic cardiomyopathy undergoing VT ablation were retrospectively analyzed. High-density EAM, cardiac magnetic resonance (CMR) post-processing with ADAS3D, and CardioMat modeling were performed. CardioMat-generated three-dimensional activation maps were integrated into the CARTO EAM suite. Deceleration zones (DZs) identified by CardioMat were compared with EAM-derived DZs and CMR-based heterogeneous tissue channels (HTCs) and scar areas. RESULTS: A total of 255 cardiac segments were analyzed. CardioMat-derived DZs demonstrated high diagnostic accuracy (79% sensitivity, 93% specificity, 81% PPV, 92% NPV, 89% accuracy) for predicting EAM-DZ localization, outperforming CMR scar and HTCs. Multivariate analysis confirmed CardioMat DZs are the strongest independent predictor of EAM-DZ localization (OR 17.4, 95% CI 6.9-43.8, p > 0.001). CONCLUSIONS: This study provides preliminary evidence supporting the feasibility of a digital twin model for noninvasive functional substrate characterization. CardioMat integrates anatomical and functional information, outperforming conventional CMR-based assessment. Prospective multicenter validation is needed to establish its role in VT ablation guidance.