Myocardial wall thinning and CT-detected thickness channels: relationship with DZ in ventricular tachycardia ablation

Introduction Ventricular tachycardia (VT) ablation in patients with structural heart disease is commonly guided by substrate-based strategies. Isochronal Late Activation Mapping (ILAM) enables the identification of deceleration zones (DZ) as potential critical isthmuses for reentry. Additionally, cardiac computed tomography (CT) allows recognition of areas of wall thinning and wall thickness channels (WTC), which may be associated with arrhythmogenic substrate. Purpose To evaluate the spatial correlation between DZ identified by ILAM and anatomical parameters derived from CT (wall thinning and WTC) in patients with ischemic cardiomyopathy (ICM) and non-ischemic cardiomyopathy (NICM) undergoing VT ablation. Methods A single-center retrospective study including 20 patients (16 ischemic, 4 non-ischemic) who underwent VT ablation with high-density endocardial mapping and advanced multimodality CT-based 3D reconstruction. Clinical characteristics, number and location of DZ, wall thinning and WTC presence, and their degree of colocalization were analyzed. Results A total of 69 DZ were identified, of which 75.4% coincided with areas of wall thinning. The sensitivity of wall thinning to predict DZ was 73.6% in ischemic and 81.2% in non-ischemic patients. DZ located over dense scar were uncommon (3.8% in ischemic, 0% in non-ischemic). WTC demonstrated moderate sensitivity (58.5% and 62.5%, respectively), but a high positive predictive value (PPV), reaching 100% in the non-ischemic group. Over a mean follow-up of 17 months, VT recurrence occurred in 35% of patients, with no significant differences between groups. Conclusions CT-derived wall thinning represents a sensitive marker for detecting functional substrate, while WTC show a high PPV, particularly in NICM. The integration of anatomical imaging and functional mapping may optimize the planning and effectiveness of VT ablation.