Integration of CT derived wall thickness mapping and functional electroanatomical analysis in ischaemic VT
K Yalin, H Yalman, A U SoysalAbstract
Background
In ischaemic cardiomyopathy, ventricular tachycardia (VT) arises from slow-conduction corridors within heterogeneous scar tissue. Functional mapping techniques such as Coherent Mapping (CM) and Isochronal Late Activation Mapping (ILAM) improve delineation of these regions; however, their anatomical correlates within computed-tomography (CT) wall-thickness (WT) maps remain incompletely defined.
Purpose
To quantify the spatial relationship between CT-derived myocardial WT and functional electroanatomical descriptors—slow-conduction zones (SCZ), deceleration zones (DZ) and lines of block (LOB)—and to evaluate the predictive value of WT-derived conduction channels (WTC) for identifying critical isthmuses.
Methods
Seven consecutive patients with prior myocardial infarction and sustained monomorphic VT underwent high-density substrate mapping using a three-dimensional electroanatomical mapping system. Pre-procedural contrast-enhanced CT data sets were segmented with a dedicated software package to generate WT maps and WTCs. CT and mapping models were coregistered. Local WT, proximity to WT ≤ 5 mm myocardium, overlap percentages and Dice similarity coefficients were calculated for SCZ, DZ and LOB regions.
Results
Eighteen SCZ, fifteen DZ and twelve LOB were identified. Functional abnormalities were almost exclusively confined to thinned myocardium. Mean WT within SCZ, DZ and LOB measured 3.6 ± 0.8 mm, 3.8 ± 0.9 mm and 4.2 ± 1.1 mm, respectively, versus 6.3 ± 1.3 mm in remote tissue (p < 0.01). SCZ overlapped with WT ≤ 5 mm regions by 74 ± 12 % (Dice 0.67 ± 0.10); DZ showed 70 ± 15 % overlap (Dice 0.63 ± 0.11). Direct correspondence between WTCs and SCZs occurred in 50 % of cases (positive predictive value 0.53; sensitivity 0.62). In the single patient with haemodynamically stable VT, the critical isthmus localised within a 2-3 mm WT region exhibiting combined CM-SCZ and ILAM-DZ overlap, where ablation terminated VT.
Conclusion
Functional slow-conduction and deceleration zones predominantly cluster within moderately thinned (≈ 3–4 mm) myocardial segments in ischaemic VT. Although CT-derived conduction channels traverse infarct border zones, their specificity for functional isthmuses is limited. WT mapping therefore provides an anatomical scaffold to guide denser functional mapping rather than a standalone ablation roadmap. Integrating anatomical and functional data enhances substrate characterisation and may streamline VT ablation strategies.figure 1figure 2