Functional ElectroAnatomiC Isochronal Late Activation Mapping for Empiric VT Ablation Trial

This is a multicenter, prospective, parallel, randomized controlled trial to test for non-inferiority with an ILAM-guided VT ablation compared to conventional voltage- based ablation. The study has two treatment arms: conventional voltage mapping and ablation (control arm). In the investigational arm, the ablation strategy is guided by ILAM to target deceleration zones, blinded to voltage mapping. In the control arm, ablation will be performed to extensively ablate all low voltage regions (\<1.5mV) during sinus rhythm, right ventricular (RV) pacing, or left ventricular (LV) pacing, with discretionary use of pacemapping and activation mapping. In both arms, mapping with be performed with a multielectrode catheter (HD Grid) and ablation will be performed using an irrigated tip catheter (FlexAbility SE or Tactiflex catheters). In the control armonly voltage mapping displays will be utilized (blinded to functional ILAM and fractionation). High density mapping with automated last deflection annotation (Ensite X) will be performed in all patients randomized to ILAM approach during either sinus rhythm or RV pacing.