Patterns of practice and treatment planning for stereotactic arrhythmia radioablation (STAR) for ventricular tachycardia: an ad-hoc analysis of the German cohort within the STOPSTORM.eu consortium

Purpose

STereotactic Arrhythmia Radioablation (STAR) is a safe and effective salvage therapy for refractory ventricular tachycardia (VT). The STOPSTORM.eu consortium has been established as a STAR registry to harmonize patient selection criteria and optimize treatment strategies. For this analysis, STAR treatments from 7 German centers were evaluated on current pattern-of-practice regarding patient selection and radiotherapy planning.

Methods

Patient characteristics and all treatment parameters were extracted from the STOPSTORM database in 07/2025. Information on patient characteristics, target volumes (TV), radiotherapy technique, dose prescription concepts, dosimetry, and motion management was evaluated.

Results

67 patients (59 male, 7 female, 1 trans-female, age mean (67 ± 9) years, range 42-85 years) with refractory monomorphic VT after no Catheter Ablation (CA) (6%), 1-2 CA (47%) or >2 CA (47%) and failed antiarrhythmic drug therapy were included in this analysis. The time between the first ICD (implantable cardioverter defibrillator) implantation and STAR was 64 months (median, range 3 days - 228 months). The type of ICD was intravascular in 91% and subcutaneous in 6%, 7% had an additional LVAD (Left ventricular assisting device) and 3% had no implanted device. The ECOG performance status before STAR was 0 (9%), 1 (2%), 2 (32%), 3 (20%) and 4 (19%) and the NYHA class was I (9%), II (35%), III (44%) and IV (12%), respectively. Median left ventricular ejection fraction (LVEF) was 34% (range 10-60%), 59% of the patients had ischemic and 41% non-ischemic cardiomyopathy. Additional comorbidities included coronary heart disease in 40%, diabetes in 13%, previous myocardial infarction in 18%, myocarditis in 6% and valve anomalies in 22%. Median time between last CA and STAR was 35 days (range 0-567 days). 19% of the patients were treated less than 14 days after CA indicating an emergency indication (e.g. VT-storm).

Information about the TV definition, dose prescription, and implementation of STAR is summarized in Table 1. Representative dose distributions for the four different prescription methods are shown in Figure 2 (A: Maximum Dose, B: Median Dose (ICRU 83), C: Coverage (ICRU 91), D: Coverage prescription (ICRU 91) with sacrificed coverage for OAR sparing (Red: Planning TV (PTV), Purple: tricuspid valve)). Note the dose heterogeneity and differing maximal doses (A vs. C) and coverage compromise in subfigure D.

Conclusion

This analysis illustrates the spectrum of STAR indications and treatment techniques in Germany. In certain aspects of the treatment, such as Clinical TV (CTV) definition and contouring, treatment goals, prescription dose, and treatment techniques, harmonization is already apparent, while patient selection and dose inhomogeneity are still largely based on individual clinician decisions. The evaluation of the full STOPSTORM database with follow-up data will open more opportunities for harmonization and optimization soon.CardTV and STAR treatment parametersDifferent dose distribution concepts