Wall thickness channels and lipomatous metaplasia assessed by cardiac computed tomography hypoenhancement as a predictors of deceleration zones in ventricular tachycardia ablation

Background Cardiac computed tomography (CCT) enables high-resolution myocardial imaging and can identify wall thickness channels (WTCs) and lipomatous metaplasia (LM) within scar regions. However, their relationship with areas of functional slow conduction—specifically, deceleration zones (DZs) identified by isochronal late activation mapping (ILAM)—remains uncertain. Objective the aim of our study was to evaluate the utility of WTCs and LM quantified by CCT hypoenhancement in identifying ILAM-defined DZs in patients with structural heart disease undergoing ventricular tachycardia (VT) ablation. Methods we retrospectively analyzed a consecutive cohort of 38 patients (67 ± 8 years; 92% male; LVEF 33 ± 9%) undergoing first VT ablation with preprocedural CCT. A total of 148 WTCs and 81 DZs were analyzed. LM was quantified across 17 AHA segments by hypoattenuation thresholds (−180 to 0 HU). The overlap between DZs, WTCs, and LM was assessed using generalized multilevel mixed-effects models. Results WTCs predicted DZs with an overall sensitivity of 69%, showing stronger predictive performance in patients with ischemic cardiomyopathy (ICM) compared with those with nonischemic cardiomyopathy (NICM). WTC length correlated significantly with the presence of DZs [OR 1.05, 95% CI 1.02–1.07; p <0.01], with a 54 mm cutoff providing the best discriminatory value. The mean LM mass per patient was 0.80 ± 0.70 g, and a significant association was found between LM mass—quantified within the AHA segments traversed by each channel—and the presence of ILAM-defined DZs [OR 2.23, 95% CI 1.43–3.47; p <0.01]. A threshold of 0.21 g yielded 89% sensitivity and 50% specificity. Decision tree analysis showed that channels >54 mm were associated with a 66% probability of DZ correlation, whereas shorter channels with LM >1.9 g had a PPV of 75%. Conversely, channels <54 mm with LM <1.9 g demonstrated an NPV of 86% for DZs. These results were consistent across ICM and NICM (interaction p = 0.70). Conclusions CCT-derived assessment combining WTC length and LM quantification enables noninvasive identification of functional slow conduction areas in patients with structural heart disease. This approach may support individualized preprocedural planning for VT ablation, particularly in settings where cardiac MRI is limited or contraindicated.