Spatial Association Between CT-Derived Myocardial Deformation and Stereotactic Radioablation Targets in Ventricular Tachycardia: Insights from the RAVENTA Trial.

BACKGROUND: Stereotactic arrhythmia radioablation (STAR) targets are typically defined by electroanatomical mapping and imaging-based substrate characterization, yet their spatial relationship to mechanically derived deformation abnormalities remains incompletely understood. OBJECTIVE: To evaluate the spatial association between CT-derived end-diastolic-end-systolic (ED-ES) radial deformation abnormalities and clinically defined STAR targets. METHODS: In nine patients undergoing STAR, three-dimensional left ventricular shells were reconstructed from ECG-gated contrast-enhanced CT. Radial deformation between ED and ES was estimated from the inter-phase displacement field, and abnormal regions defined by a patient-specific threshold at the lower 10th percentile of voxel-wise radial deformation. STAR targets were transferred from voltage maps onto the CT geometry. Spatial relationships were assessed using centroid distance, mean surface distance, volumetric overlap, and segment-level concordance. RESULTS: Eleven abnormal radial deformation regions and 11 STAR targets were identified. At the segment level, radial deformation discriminated target-positive segments (AUC 0.80, 95% CI 0.73-0.88) significantly better than longitudinal deformation (AUC 0.71, 95% CI 0.66-0.76; DeLong p < 0.001). Median centroid distance between abnormal regions and STAR targets was 20.4 mm (IQR 15.4-33.7) and median mean surface distance 6.0 mm (IQR 2.8-9.7). Partial volumetric overlap occurred in 9 of 11 deformation-defined regions, and 10 of 11 STAR targets overlapped at least one deformation-defined abnormality. Abnormal radial deformation was present in 18 of 21 target-positive segments (86%) versus 41 of 129 target-negative segments (32%). CONCLUSIONS: CT-derived ED-ES radial deformation abnormalities show substantial spatial association with clinically defined STAR targets, alongside partial discordance, and may complement substrate characterization in patients undergoing STAR.