Substrate-based approach for ventricular tachycardia in structural heart disease: Tips for mapping and ablation

AbstractCatheter ablation of scar-related ventricular tachycardia (VT) often relies on substrate-based approaches because of hemodynamic instability during VT, multiple VT morphologies, and poor reproducibility of VT-inducibility, rendering the VT unmappable. As substrate-guided ablation is performed in stable sinus rhythm, any VT can potentially be targeted regardless of its hemodynamic state. So-called “late potentials,” conventionally defined as signals detected after the end of QRS, have been traditionally proposed as ablation targets. However, late potentials cannot be detected in up to 30% of patients with VT in the setting of ischemic and non-ischemic cardiomyopathy. Recently, a substrate-based approach that targets poorly coupled fibers surviving within the scar has been developed. These bundles generate local abnormal ventricular activities (LAVA) and are believed to be responsible for VT. Considering the limitations of late potential ablation, substrate homogenization with the aim of eliminating all identified LAVA appears to be an ideal procedural endpoint. This article reviews substrate-based approaches and tips for mapping and ablation of VT substrate