ESTRO 2024 - Abstract Book

S2966

Interdiscplinary - Other

ESTRO 2024

2716

Digital Poster

Dosimetric analysis of a novel approach on Cardiac Ablative Radiotherapy for Ventricular Tachycardia

Gabriela Antelo 1 , Carla Cases 1 , Maria Laplana 1 , Sara Vazquez 2 , Joel Mases 1 , Tanny Barreto 1 , Gabriela Oses 1 , Sara Moreno 1 , Francesc Leon 1 , Carlos Clavell 1 , Ivo Roca 2 , Meritxell Mollà 1 1 Hospital Clinic Barcelona, Radiation Oncology, Barcelona, Spain. 2 Hospital Clinic Barcelona, Cardiology, Barcelona, Spain

Purpose/Objective:

STereotactic Ablative Radiotherapy (STAR) for Ventricular Tachycardia (VT) has shown worldwide promising results over the last decade for patients unfit or resistant to catheter ablation and antiarrhythmic drugs. However, a significant challenge arises from the volume and location of this area due to normal tissue constraint dose restrictions. Our STAR team has come up with a different procedure to successfully control the ventricular tachycardia while sparing nearby organs at risk (OAR). This approach was used to treat a patient with a ventricular aneurysm in the inferior wall of his left ventricle (diameter 72 mm) with an intracavital thrombus and ventricular tachycardia (VT) storm arising from multiple arrhythmogenic focus localized around the aneurysm wall. The standard STAR approach is to encompass all the arrhythmogenic focus, therefore our clinical target volume would be the entire aneurysm. The major limitation of this plan was that the inferior side of the aneurysm wall was too close to the stomach to accomplish dose constraints. To avoid this limitation, we designed an innovative STAR plan, selecting a smaller volume of the arrhythmogenic area. The rationale behind this approach was to ablate the arrhythmogenic focus while isolating the rest of the aneurysm tissue, thereby stopping the arrhythmic flow from spreading through the rest of the myocardial wall and preventing the recurrence of VT storm. We performed two different STAR plans (25Gy, single dose) and conducted a dosimetric comparison between them. The standard STAR plan (case 1) encompassed the entire aneurysm wall, as it contained multiple arrhythmogenic focus. In contrast, our plan (case 2) only considered the arrhythmogenic focus. We considered breathing movement using an ITV approach for both plans. To compare both plans we registered OAR constraints according to our institution protocol, thus: Aorta, atrium left (L) and right (R), bronchial tree, left coronary, right coronary, implantable cardioverter-defibrillator (ICD), esophagus, heart, heart+pericardium, left anterior descending artery, liver, lungs (L,R), pericardium, pulmonary artery, skin, spinal cord, stomach, trachea, cava vein (superior and inferior), and ventricles (L, R) (Table 1). We also compared PTV volume, 25 Gy and 12,5 Gy isodose volumes. Material/Methods: