Three-Dimensional Perspective on Scar-Related Ventricular Tachycardia Substrate: Critical Conduction Abnormalities as Ablation Targets and Implications for Procedural Endpoints.

Scar-related ventricular tachycardia (VT) is increasingly recognized as a three-dimensional (3D) arrhythmia sustained by complex reentrant circuits that frequently involve intramural components. Advances in high-density and high-resolution electroanatomical mapping have shifted the paradigm of substrate characterization from purely voltage-based structural definitions toward functional assessment of conduction delay and wavefront discontinuity. Recent studies have described techniques that target critical conduction abnormalities associated with VT circuits, including deceleration zones, lines of conduction block, and rotational activation patterns. A central concept underlying these approaches is that VT substrates are volumetric structures constrained by lateral and depth-oriented boundaries rather than planar pathways. Within this 3D framework, targeted ablation strategies that interrupt functionally relevant conduction abnormalities, rather than empirically modifying scar, have demonstrated clinical outcomes comparable to those of extensive homogenization approaches while potentially reducing procedural burden. Intramural reentry remains a major challenge because surface-based mapping incompletely captures mid-myocardial conduction, and current techniques for real-time intraprocedural assessment of intramural abnormalities remain limited. Adjunctive strategies, including differential pacing, refined annotation methods, and peak frequency analysis, may improve identification of critical substrate components, although no single parameter reliably defines the optimal ablation target. Accordingly, procedural endpoints should evolve beyond empirical surrogates such as VT termination or noninducibility toward confirmation of effective disruption of the 3D arrhythmogenic substrate. Continued integration of advanced mapping technologies, imaging, and lesion-delivery innovations will be essential to refine both ablation strategies and procedural endpoints in scar-related VT.