ESTRO 2024 - Abstract Book

S2013

Clinical - Mixed sites, palliation

ESTRO 2024

Cardiovascolari, Rome, Italy. 12 Fondazione Policlinico Universitario A. Gemelli IRCCS, radiation ongcology, rome, Italy. 13 San Pietro FBF, radiation ongcology, Rome, Italy

Purpose/Objective:

Ventricular Tachycardia Ablation by Radiation Therapy (VT-ART) for ventricular tachycardia (VT) is promising. Definitive data on efficacy are lacking. Most of the available case series account for limited number of patients -pt- (ranging 5-20). Defining the best RT procedure is also an issue. Aim of this multicenter study is to evaluate VT- ART‘s homogeneity and efficacy on a large cohort.

Material/Methods:

We collected pt undergone to VT-ART for refractory VT, within a spontaneous network among Centers having performed preliminary experience for limited series, outside clinical trials. No restriction about pt selection and VT ART treatment administration were applied. Collected variables focused on both treatment efficacy and procedural homogeneity

Results:

Six Centers collaborated, enrolling 21 pt. Not each of the data required by the promoting Center were available for all the sub- series, depending on the center’s trend for default data collection. Based on the shared variables: range of recruitment was September 2019-February 2023; all pt were male; mean pt age was 69,7 years (range, 52-87). Pretreatment mean left ventricular ejection fraction was 33% (range22-50). All pt underwent at least one radiofrequency catheter ablation. Linac dedicated to SBRT was used in 11/21(52,4%) pt; 6/21 (28,6%) used MRgRT; 4/21 (19%) used conventional Linac. In 7/21 (33,4%) free breathing 4D simulation, and in 12/21 (57%) a gated breath hold (deep inspiration) was performed. Target delineation procedure varied among Centers. Although choosen references for constraints were similar among centers, the applied ones ranged 1-7 different guidelines. The mean CTV volume of the was 71,3 cc (range 8.9-238.5). The mean PTV margin provided was 3,3 mm (range 3-5). For all pt, SBRT was performed with a dose of 25 Gy in single fraction; prescription isodose was 97% in 1/21, 95% in 3/21, 94% in 1/21, 80% in 15/21 pts, 75% in 1/21(mean 87,5%). PTV mean Dose was 27,6 Gy (23,4-29,7). Briefly, each of the 6 RT Centers applied its IGRT inner rule; online monitoring was performed through 4D gating control in all cases adding peculiar approaches in 2/6 Centers. Further analyses will be collected and presented at the Congress.

Conclusion:

The presented series is one of the largest collected. Feasibility of VT-ART seems confirmed. High homogeneity in dose prescription is confirmed. Still relevant differences on details of delineation, treatment planning and procedural settings are reported. For brevity further details will be specified at the conference

Keywords: Radioablation; Ventricular arrythmia; non-oncol