Does integrating multipolar and wavefront annotation with CT-derived wall thinning analysis improve the identification of critical substrates in scar-related ventricular tachycardia?
CT-derived wall thinning alone is insufficient for precise localization of VT-critical sites, but its integration with multipolar annotation improves target identification.
Abstract Introduction Catheter ablation (CA) for scar-related ventricular tachycardia (VT) remains challenging due to high recurrence and long procedures. CT-derived wall thinning correlates with abnormal electrograms in ischemic cardiomyopathy 1,2 but shows limited predictive value for identifying deceleration zones 3. Although thinned scar indicates conduction slowing, it alone may not define VT-critical sites. Digital-twin imaging provides three-dimensional (3D) substrate characterization 4, but its direct correspondence with VT mapping remains unclear. Purpose This study assessed the electrophysiological and anatomical characteristics of VT circuits by integrating activation-based annotation algorithms with CT-derived wall-thinning analysis. Methods From 2024 to 2025, five patients (3 men, age 60 ± 21 years) with sustained monomorphic VT underwent CA. In two ischemic cardiomyopathy cases, CT data were used to generate wall-thinning maps. Mapping data were retrospectively annotated with multipolar and wavefront algorithms and merged with 3D CT models. VT-critical sites were defined as radiofrequency points that terminated VT. Results A total of 24,017 and 37,084 mapping points were analyzed with multipolar and wavefront annotation, respectively. In the multipolar analysis, VT-critical sites (n=256) had lower unipolar (2.6 ± 3.4 vs 4.4 ± 2.8 mV, P0.001) and bipolar voltages (0.4 ± 0.3 vs 0.6 ± 1.3 mV, P=0.009) than non-critical sites (n=23,761) and more often coincided with wall thinning ≤5 mm (28.9% vs 21.4%, P=0.004) and wall-thickness channels (21.1% vs 16.5%, P=0.047). In the wavefront analysis, VT-critical sites (n=445) showed lower unipolar (3.4 ± 1.6 vs 3.6 ± 2.4 mV, P=0.023) and bipolar voltages (0.4 ± 0.7 vs 0.6 ± 1.1 mV, P0.001) and shorter fractionation durations (94.4 ± 38.2 vs 109.5 ± 42.8 ms, P0.001). Concordance with wall thinning ≤5 mm (13.0% vs 23.7%, P0.001) and wall-thickness channels (7.9% vs 11.1%, P=0.032) was lower, as shown in Figure, suggesting VT-critical sites may not always overlap with thinned regions on CT. Within wall-thickness channels, 3,965 multipolar and 4,091 wavefront points were analyzed. VT-critical sites on these channels (54 and 35 points) were compared with non-critical sites. In the multipolar analysis, no voltage differences were seen in unipolar (3.1 ± 7.0 vs 3.7 ± 2.5 mV, P=0.102) or bipolar values (1.1 ± 7.1 vs 0.4 ± 1.8 mV, P=0.437). In the wavefront analysis, VT-critical sites showed lower unipolar (2.4 ± 0.8 vs 3.2 ± 1.8 mV, P0.001) and bipolar voltages (0.2 ± 0.2 vs 0.4 ± 0.7 mV, P0.001) and shorter fractionation durations (97.2 ± 31.1 vs 112.5 ± 42.3 ms, P=0.049). Conclusion VT-critical sites showed low voltage across annotation algorithms. CT-derived wall thinning alone was insufficient for precise localization, but integration with multipolar annotation improved target identification. Identifying wall-thickness channels before CA may further aid localization of VT-critical sites.
Hachisuka et al. (Mon,) studied this question.