Patients with refractory ventricular extrasystoles or tachycardia not eligible for catheter ablation will receive single fraction stereotactic body radiation therapy (cardiac radiosurgery) with 25 Gy.

Investigators initiated this study to demonstrate that in at least 70% of the patients the planned cardiac radiosurgery may be performed without any interruption or treatment related interventional events within the first 30 days after treatment.

Primary endpoint: 30-day post-intervention safety defined as presence of both, radiosurgery delivery of the planned dose to the intended target area, and no possibly treatment related serious adverse events in the first 30 days after treatment.

Secondary endpoints: evaluated at 1 year

• Changes in ventricular tachycardia episodes and ICD shocks
• Changes in antiarrhythmic medication due to treatment effects
• Occurrence of possibly treatment related adverse events in the first year after treatment
• Changes in patient-reported quality of life
• Overall survival
• Safety profile

Inclusion Criteria:

• Patients with structural heart disease and implantable cardioverter defibrillator (ICD)

• Age > 18 years

• either

  1. Recurring symptomatic monomorphic ventricular tachycardia that requires ICD intervention (e.g. shock or anti-tachycardia stimulation). At least 3 episodes within the 3 months prior to inclusion or
  2. induction of symptomatic monomorphic ventricular tachycardia that requires ICD intervention (e.g. shock or anti-tachycardia stimulation). Induction triggered by ICD or during electrophysiology studies (EPS) or both, a) and b)

• Refractory to antiarrhythmic combination therapy

• Beside the cardiac conditions: No competing illness that would additionally limit the life expectancy to less than 6 months

• No prior radiation therapy in the thorax area

• No pregnancy and no active breastfeeding

• Ability to consent and consent to study participation

Exclusion Criteria:

• ICD electrode malfunction of ICD readings outside reference range
• Lack of evidence of a myocardial scar (Computer tomography or magnetic resonance tomography for MRI-capable ICD aggregates or electrophysiological measurement)
• No possible induction of symptomatic monomorphic ventricular tachycardia non-persistent or persistent with delivery of ICD therapies such as antitachycardic pacing or shock
• Contraindication to radiosurgery (e.g. precise target volume definition not possible due to image artifacts created from a left ventricular assist device (LVAD))
• Inability to consent or missing or withdrawn consent