ESTRO 2025 - Abstract Book

S1476

Clinical – Mixed sites & palliation

ESTRO 2025

1 Klinik für Strahlentherapie, Universitätsklinikum Schleswig-Holstein, Kiel, Germany. 2 Klinik für Innere Medizin III, Kardiologie, Abteilung für Elektrophysiologie und Rhythmologie, Universitätsklinikum Schleswig-Holstein, Kiel, Germany. 3 Klinik für Strahlentherapie und Radioonkologie, Universitätsmedizin Mannheim, Mannheim, Germany. 4 Medizinische Klinik I, Abteilung für Elektrophysiologie und Rhythmologie, Universitätsmedizin Mannheim, Mannheim, Germany. 5 Klinik für Radioonkologie und Strahlentherapie, Charité Universitätsmedizin Berlin, Berlin, Germany. 6 Klinik für Kardiologie, Angiologie und Intensivmedizin, Campus Virchow Klinikum, Deutsches Herzzentrum der Charité Universitätsmedizin Berlin, Berlin, Germany. 7 Hannover Herzrhythmus Centrum, Klinik für Kardiologie und Angiologie, Medizinische Hochschule Hannover, Hannover, Germany. 8 Klinik für Strahlentherapie, Medizinische Hochschule Hannover, Hannover, Germany. 9 Klinik für Strahlentherapie, Universitätsklinikum Schleswig-Holstein, Lübeck, Germany. 10 Klinik für Rhythmologie, Universitätsklinikum Schleswig-Holstein, Lübeck, Germany. 11 , Klinik für Strahlentherapie und Radioonkologie, Ludwig-Maximilians-Universität München, Klinikum der LMU, München, Germany. 12 Medizinische Klinik und Poliklinik I, Ludwig-Maximilians-Universität München, Klinikum der LMU, München, Germany. 13 Partnerzentrum Berlin, Deutsches Zentrum für Herz-Kreislauf-Forschung (DZHK), Berlin, Germany. 14 Elektrophysiologie Bremen, Herzzentrum Bremen, Bremen, Germany. 15 Klinik für Kardiologie, Angiologie und Intensivmedizin, Campus Mitte, Deutsches Herzzentrum der Charité Universitätsmedizin Berlin, Berlin, Germany Purpose/Objective: Stereotactic Arrhythmia Radioablation (STAR) has been used as a novel bail-out treatment strategy for patients with refractory ventricular-tachycardia (VT). We report the results of the method-harmonized, quality-assured, multicenter RAdiosurgery for VENtricular TAchycardia (RAVENTA) study (NCT03867747) [1] as part of the STOPSTORM project (EU-Horizon-2020-Grant 945119) [2]. cardiomyopathy: 11/20, prior catheter ablations: 0-8 [median:2.5]; left-ventricular-ejection-fraction [LVEF]: 10-60% [median:31.5%]) were treated at six German university centers. Median cardiac-target-volume determined by electrophysiological-mapping and/or scar-imaging (CardTV_EP/IMG) and planning-target-volume (PTV) were 16.5ml (range:6.0-87.8ml) and 74.8ml (range:31.7-144.3ml), respectively. Prescription dose was 25Gy in all cases with PTV D98%, D50% and D2% doses of 19.3-25.4Gy (median:24.6Gy), 26.1-29.1Gy (median:27.9Gy) and 27.3-31.6Gy (median:29.7Gy), respectively. Most patients were treated with stereotactic linear-accelerators with intensity modulated-arc-therapy (16/20) and internal-target-volume approach for motion compensation (15/20). Median first to-last beam-on time was 16min (range:4-100min). Results: All treatments were successfully completed and no possibly treatment-related severe periprocedural complications were noted in the first 30 days after STAR (primary endpoint). Three patients died during follow-up, one in electrical storm at 7 weeks, one from retroperitoneal hemorrhage at 8 months and one from heart failure at 10 months, and two patients received a heart transplant after STAR (both alive at study end). Combined, thirty-six not possibly treatment- related serious adverse events and one grade ≥ 3 toxicity possibly related to STAR (progression of heart disease 2 months after STAR requiring heart transplant) were reported. Five and two of eighteen patients that reached the 3 months follow-up showed asymptomatic pneumonitis or pericardial effusion, respectively, and were conservatively managed. Fifteen patients reached the regular study end at one year, fourteen of them VT free, ten without further intervention after STAR, with a median LVEF of 34.5% (range: 27-55%). Overall, six patients required further catheter/alcohol ablation or sympathectomy, four with recurrences in or near the STAR treatment locations, resulting in a total local efficacy (freedom from index VT) of 73.7% (14/19) with a tendency of better local efficacy for ischemic as compared to non-ischemic cardiomyopathy patients (85.7% vs. 50.0%). Material/Methods: From 11/2019-10/2023, 20 patients (male: 17, female: 3; age: 49-84 [median:64] years; non-ischemic