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The current management of refractory ventricular tachycardia (RVT) is represented by catheter ablation. Nevertheless, this cardiological procedure is associated with a risk of complication and some patients are not eligible. Recently, initial clinical experiences are exploring the role of stereotactic arrythmia radioablation (STAR) as an emerging alternative approach in selected patients. Nevertheless, a standardized method to deliver ablative doses to the heart is not yet available and several questions are still under debate, including: diagnostic radiological exams, target delineation, organ motion management, efficacy and safety. In the present study, we reported the preliminary results about the role of STAR in the management of patients with RVT.

Patients with a diagnosis of RVT, excluded from other cardiological procedures, were defined as eligible to STAR. All patients should receive a 3D Electroanatomic Mapping, a cardio-CT scan and cardiac 18F-fluoro-2-deoxy-D-glucose positron emission tomography (18FDG – PET scan) in order to identify the ventricular target pathological area. Cardiac MR was offered only in patients with a defibrillator compatible with magnetic resonance. In all cases, a 3 mm-slice thickness 4D-CT scan with the aid of an abdominal thermoplastic mask was used. 4D-CT scan supports the radiation oncologist to evaluate the heart motion. Cardio-CT scan a 18FDG-PET scan were registered to the average CT simulation scan in order to identify the pathological ventricular area. The target definition was outlined by radiation oncologist and cardiologist. The gross tumor volume (GTV) was delineated as the hypometabolic 18FDG-PET ventricular area. The planning target volume (PTV) was obtained by adding an isotropic margin of 5 mm to the GTV. Dose prescription ranged between 21 and 25 Gy in a single fraction. In all cases were treated with a TrueBeam Linac (Varian Medical Systems, Palo Alto, CA). An approval of the ethics committee was obtained before each radiation treatment.

From January 2020 to March 2021, 6 RVT patients (5 male and 1 woman) were considered eligible to STAR treatment. The median age was 78 (58-80 years) and median performance status was 2 (range 0-4). Median GTV and PTV volumes were 33 cc (range 10.4-73.3 cc), and 90.8 cc (range 45.9 – 190.1 cc), respectively. Median prescription dose was 25 Gy (range 21-25 Gy). At a median follow-up of 13 months, an efficacy of STAR treatment was observed in 4 patients. Cardiologist did not record additional defibrillator activation. One patient had RVT recurrence after 3 months by the end of radiotherapy and one patient died due to cardiac failure. No severe acute toxicity was recorded after radiation therapy.

STAR treatment seems to be a safe and efficacy approach. Additional data are necessary in order to standardize this approach in RVT patients not eligible to cardiological procedure