Stereotactic Arrhythmia Radioablation (STAR): Ad Hoc Analysis of the Treatment Characteristics of the German Patients in the STOPSTORM.eu Consortium Registry Trial

E. Lian (Kiel)¹, M. Grehn (Kiel)², S. Mandija (Utrecht)³, F. Mehrhof (Berlin)⁴, F. Hohendanner (Berlin)⁵, G. Hindricks (Berlin)⁶, S. Hohmann (Hildesheim)⁷, R. Merten (Hannover)⁸, D. Duncker (Hannover)⁹, C. G. Veltmann (Bremen)¹⁰, S. Quick (Chemnitz)¹¹, S. Jaschik (Chemnitz)¹², M. Christoph (Chemnitz)¹¹, G. Klautke (Chemnitz)¹², B. Rudic (Mannheim)¹³, L. Kaestner (Mannheim)¹⁴, J. Boda-Heggemann (Mannheim)¹⁴, M. F. Sinner (München)¹⁵, S. Corradini (München)¹⁶, M. Ebert (Dresden)¹⁷, S. Richter (Dresden)¹⁸, A. Lattermann (Dresden)¹⁹, J. Vogler (Hamburg)²⁰, S. Ș. Popescu (Lübeck)²¹, D. Rades (Lübeck)²², A. Zaman (Kiel)¹, O. Wittenstein (Kiel)², D. Krug (Kiel)², J. Dunst (Kiel)², D. Frank (Kiel)¹, E. Pruvot (Lausanne)²³, J. J. Verhoeff (Amsterdam)²⁴, M. F. Fast (Utrecht)³, R. R. Tilz (Lübeck)²¹, O. Blanck (Kiel)^2
1Universitätsklinikum Schleswig-Holstein Innere Medizin III mit den Schwerpunkten Kardiologie, Angiologie und internistische Intensivmedizin Kiel, Deutschland; ²Universitätsklinikum Schleswig-Holstein Klinik für Strahlentherapie Kiel, Deutschland; ³University Medical Center Utrecht Department for Radiotherapy Utrecht, Niederlande; ⁴Charité - Universitätsmedizin Berlin Kaufmännische Centrumsleitung, Charité Centrum 14 Berlin, Deutschland; ⁵Deutsches Herzzentrum der Charite (DHZC) Klinik für Kardiologie, Angiologie und Intensivmedizin | CBF Berlin, Deutschland; ⁶Charité - Universitätsmedizin Berlin CC11: Med. Klinik m. S. Kardiologie und Angiologie Berlin, Deutschland; ⁷St. Bernward Krankenhaus Med. Klinik I - Kardiologie Hildesheim, Deutschland; ⁸Medizinische Hochschule Hannover Klinik für Strahlentherapie Hannover, Deutschland; ⁹Medizinische Hochschule Hannover Klinik für Kardiologie und Angiologie Hannover, Deutschland; ¹⁰Elektrophysiologie Bremen Lilienthal, Deutschland; ¹¹Klinikum Chemnitz gGmbH Innere Medizin I - Kardiologie Chemnitz, Deutschland; ¹²Klinikum Chemnitz Klinik für Radioonkologie Chemnitz, Deutschland; ¹³Universitätsklinikum Mannheim GmbH I. Medizinische Klinik Mannheim, Deutschland; ¹⁴Universitätsmedizin Mannheim Klinik für Strahlentherapie und Radioonkologie Mannheim, Deutschland; ¹⁵LMU Klinikum der Universität München Medizinische Klinik und Poliklinik I München, Deutschland; ¹⁶Ludwig-Maximilians-Universität München, Klinikum der LMU Klinik für Strahlentherapie und Radioonkologie München, Deutschland; ¹⁷Herzzentrum Dresden GmbH an der TU Dresden Klinik für Innere Medizin, Kardiologie und Intensivmedizin Dresden, Deutschland; ¹⁸Herzzentrum Dresden GmbH an der TU Dresden Klinik für Innere Medizin und Kardiologie Dresden, Deutschland; ¹⁹Universitätsklinikum Carl Gustav Carus Dresden Klinik für Strahlentherapie und Radioonkologie Dresden, Deutschland; ²⁰Asklepios Klinik St. Georg Kardiologie & internistische Intensivmedizin Hamburg, Deutschland; ²¹Universitätsklinikum Schleswig-Holstein Klinik für Rhythmologie Lübeck, Deutschland; ²²Universitätsklinikum Schleswig-Holstein Klinik für Strahlentherapie Lübeck, Deutschland; ²³Lausanne University Hospital Heart and Vessel Department Lausanne, Schweiz; ²⁴Amsterdam University Medical Center Department of Radiation Oncology Amsterdam, Niederlande

Background
Stereotactic Arrhythmia Radioablation (STAR) is a novel, promising treatment option for refractory ventricular tachycardia (VT). However, only limited single center case series and clinical trials have been reported until now. Pooled clinical data from large multicenter multiplatform trials and registries are eagerly awaited.

Methods
The purpose of the Standardized Treatment and Outcome Platform for Stereotactic Therapy Of Re-entrant tachycardia by a Multidisciplinary (STOPSTORM) consortium (EU-Horizon-2020 Grand No. 945119) is to generate a treatment registry and to optimise and harmonise STAR for VT across Europe [1]. The STOPSTORM project includes 57 clinical and research institutes in 10 European countries and is divided into 8 work packages: Registry Trial: Observational Cohort; Standardisation of Target Delineation; Registry Trial: Harmonized Cohort; Quality Assurance with Standardisation of Treatment Planning and Reporting; Analysis and Evaluation; Ethics; Dissemination; and Project Management. We now present an ad hoc analysis of the treatment characteristics of the German patients at seven medical centers in the STOPSTORM Registry Trial (observational and harmonized cohort combined).

Results
Fifty-six patients (median age 68 [range: 49-88] years, 88% male) who were treated with STAR from 11/2018 to 09/2024 in Germany are included in the STOPSTORM database until 11/2024. About half the patients had ischemic cardiomyopathy, while the other half had non-ischemic cardiomyopathypredominantly dilated. Most patients were classified as NYHA class III and IV (70%). Among these patients, roughly one-third had coronary heart disease, one-fourth had valvular disease or abnormalities and 10% have diabetes. Patients underwent a median of 2 (range 0-8) prior catheter ablations and most patients were on 200 mg Amiodaron and betablockers daily. Additional anti-arrhythmic medications, such as lidocaine or mexiletine varied among patients. Median cardiac target volume determined by electrophysiological mapping and/or scar imaging (CardTV_EP/IMG) and planning target volume (PTV) were 10.7 ml (range: 5.5-87.8 ml) and 64.6 ml (range: 10.8-156.9 ml), respectively. Of note, the treated target volumes appear to be smaller in comparison to case series reported from the USA. The prescription dose was 25 Gy in all cases with varying dose inhomogeneity within the PTV. The primary radiation techniques used was predominately Intensity Modulated Arc Therapy (85%) employing half active (gating, compression) and half passive (internal target volume) motion management techniques. Median treatment time was approximately 10 minutes (without patient setup time), but ranged up to 100 minutes.

Conclusion
The STOPSTORM.eu consortium is pooling STAR treatment data from over 50 centers in 10 countries in Europe. In Germany, more than 50 patients have been entered to date into the STOPSTORM registry database, where patients have been treated with STAR as bail-out strategy for refractory VT after various standard treatments (multiple catheter ablations and maxed anti-arrhythmic medication). Follow up-data is eagerly awaited to evaluate toxicity and efficacy of this novel treatment and will be presented at the congress.

References

[1] Grehn M, et al. STereotactic Arrhythmia Radioablation (STAR): the [STOPSTORM.eu] consortium and review of current patterns of STAR practice in Europe. Europace. 2023 Apr 15;25(4):1284-1295.