PMC9441661_01
Anatomical details reconstructed from the preprocedural cardiac CT scan. Aorta in red, left atrium in yellow, right atrium in purple, and right ventricle in green.
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Electroanatomic (EAM) activation and substrate maps were acquired (CARTO3, Biosense Webster, Irvine, CA, USA) and merged with pre-procedural CT scan (Figure 1).
(A) Endocardial electroanatomic substrate map (CARTO3, Biosense Webster, Irvine, CA, USA) obtained from the second VT ablation procedure. The map highlights the area of late potentials (LPs) characterized by a local late activation time (LAT) after paced QRS end, located at the basal inferolateral segment of the left ventricle. Mesodiastolic potentials (MPs) recorded during the clinical VT were located at the same spot of the farthest LPs. (B) Integration of CT imaging with CARTO imaging data (bipolar voltage map). In both (A,B), the white outlined area is the arrhythmogenic target for STAR identified at EAM mapping. (C) LV short axis view of cardiac CT angiographic phase with thinned basal inferolateral myocardium. (D) LV short axis view of late cardiac CT phase with hyperdensity on basal inferior-lateral wall that represents transmural fibrosis.
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Activation mapping during the clinical VT confirmed exit from the same spot identified at the first procedure (Figure 2A), which also showed an excellent 97% morphological matching during pacemapping in the site of mesodiastolic potentials; therefore, consolidation of the previous lesions at this spot was performed. Additionally, in an attempt to reduce the risk of recurrences, a subsequent substrate mapping during RV stimulation was performed, which led to the extension of the ablation lesions in the surrounding basal inferolateral area of the LV (white outlined area of Figures 2A,B) and, to a much lesser extent, to the anterolateral mediobasal regions of the LV (not shown in Figure 2). A thinned basal inferolateral myocardium with transmural DE was identified (Figures 2C,D). Accordingly, the target volume was in the basal inferolateral region of the LV (white outlined area in Figures 2A,B). The 3D reconstruction of the LV and of the contoured GTV, also including the ascending aorta and the prosthetic mitral valve, is shown in Supplementary Figure 2; the figure underlines the relationship between the GTV and the mitral valve.
STAR treatment plan. Treatment plan in axial (A), sagittal (B), and coronal (C) orientation are shown, with dose volume histogram (25 Gy is prescribed on 80% isodose).
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Figure 3 illustrates the dose distribution achieved with the VMAT plan.