CArdiac STereotactic Radiation Treatment for Ablation of ventRicular Tachycardia (CASTAR)

The investigator-initiated, CArdiac Stereotactic radiation Treatment for Ablation of ventRicular tachycardia (CASTAR) study will be conducted in patients with ventricular tachycardia (VT) which is either refractory to antiarrhythmic medication therapy in maximal dose or to catheter ablation or with contraindications to antiarrhythmic medication or catheter ablation.

The study is a non-randomized, multicenter, interventional study of cardiac SBRT, for which a total dose of 25 Gy will be delivered in a single fraction using volumetric modulated arc therapy (VMAT). The aim of the CASTAR study is to assess the feasibility and the safety of cardiac SBRT for the treatment of VT. Secondary objectives are efficacy, toxicity and QoL of cardiac SBRT for Ventricular tachycardia .

Study Overview

• Status: Recruiting
• Conditions: Ventricular Tachycardia
• Intervention / Treatment: Radiation: Stereotactic body radiation therapy (SBRT)

Detailed Description

The study will be conducted at multiple centers across Belgium. Twenty patients will be enrolled to the study. Interim analyses are planned to be performed when the first five or ten subjects have been treated. Participation in the study will comprise a screening period, where screening assessments must be completed before starting treatment. Eligible, consenting patients will then undergo SBRT, which is limited to a single dose delivery on one day. During SBRT, patients are closely monitored in accordance with the DEGRO guidelines for radiotherapy in patients with ICDs (Gauter-Fleckenstein 2015). After SBRT, patients will be closely monitored during a 3-5 days hospitalization. The post-treatment phase will start after patients are discharged from the hospital. Patients will be followed on regular basis to assess safety and efficacy of SBRT treatment.

• Study Type: Interventional
• Enrollment (Estimated): 20
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Belgium
  • Belgium
    • Antwerp, Belgium, Belgium, 2610
      • Recruiting
      • ZAS Augustinus
      • Contact: Ines Joye, PhD; Phone Number: +32 3 443 37 37; Email: ines.joye@zas.be
      • Principal Investigator: Ines Joye, PhD
    • Edegem, Belgium, Belgium, 2600
      • Recruiting
      • UZA
      • Contact: Johan Saenen, PhD; Phone Number: + 32 3 821 53 16; Email: johan.saenen@uza.be
      • Principal Investigator: Johan Saenen, PhD

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

Inclusion Criteria:

• Patients over the age of 18 with structural heart disease
• Patients with ventricular tachycardia requiring intervention (e.g. an electrical shock or anti-tachycardia pacing via an Implantable Cardioverter Defibrillator (ICD)) which cannot be managed with medication or catheter ablation, or where there are contraindications to treatment with medication or catheter ablation.
• Contraindications may exist due to comorbidities or due to the type or severity of the disease.
• Informed consent to participate has been obtained from the patient or from his or her legal representative.

Exclusion Criteria:

• Lack of evidence that the ventricular tachycardia is triggered by myocardial scarring (based on MRI, CT EAM).
• Any contraindication to radiosurgery (e.g. inability to precisely define the target volume due to imaging artefacts caused by an LVAD)
• Pregnancy
• Previous radiotherapy that prevents the safe delivery of the dose.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: SBRT; A single radiation dose of 25 Gy is delivered to the VT target.	Radiation: Stereotactic body radiation therapy (SBRT); Stereotactic body radiation therapy (SBRT): a single radiation dose of 25 Gy is delivered to the VT target.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Feasibility of SBRT for the treatment of ventricular tachycardia	Feasibility will be assessed as the successful implementation and completion of cardiac SBRT without interruption of treatment. SBRT consists of a single fraction of 25 Gy delivered to the ventricular tachycardia target.	Day of SBRT treatment (Day 1)
Safety of SBRT for the treatment of ventricular tachycardia.	Safety will be assessed by the incidence and severity of adverse events related to radiotherapy following cardiac SBRT. Adverse events will be assessed and graded according to the National Cancer Institute Common Terminology Criteria for Adverse Events (NCI CTCAE), version 5.0.	From SBRT treatment through 31 days after SBRT

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in ventricular tachycardia burden following SBRT	The ventricular tachycardia (VT) burden will be assessed by the number of VT episodes recorded by ECG and implantable cardioverter-defibrillator (ICD) readouts. The number of VT episodes during the 6 months following SBRT will be compared with the number during the 6 months preceding SBRT. A 6-week blanking period immediately following SBRT will be taken into account in the analysis of VT recurrences.	6 months before SBRT through 6 months after SBRT
Time from SBRT to first VT recurrence	Time from SBRT treatment to the first documented recurrence of ventricular tachycardia, as determined from ICD readouts. A 6-week blanking period following SBRT will be considered in the analysis of VT recurrence.	From SBRT through 36 months after treatment
Time from SBRT to first sustained ventricular tachycardia or ICD shock	Time from SBRT treatment to the first occurrence of sustained ventricular tachycardia or the first appropriate ICD shock during follow-up.	From SBRT through 36 months after treatment
Time from SBRT to first ventricular tachycardia storm	Time from SBRT treatment to the first occurrence of a ventricular tachycardia storm during follow-up.	From SBRT through 36 months after treatment
Change in the number of electrical storms following SBRT	The number of electrical storms occurring following SBRT will be compared with the number occurring before SBRT treatment.	6 months before SBRT through 6 months after SBRT
Change in anti-tachycardia pacing and ICD shocks following SBRT	The number of anti-tachycardia pacing (ATP) interventions and ICD shocks following SBRT will be compared with the number occurring before SBRT treatment.	6 months before SBRT through 6 months after SBRT
Change in anti-arrhythmic medication use following SBRT	Anti-arrhythmic medication use will be assessed during follow-up. The type and dosage of anti-arrhythmic drugs will be collected to evaluate changes in the need for anti-arrhythmic treatment following SBRT.	From baseline through 36 months after SBRT
Overall survival following SBRT	Overall survival will be assessed from the date of SBRT treatment until death from any cause.	From SBRT through 36 months after treatment
Incidence of heart transplantation following SBRT	The number and proportion of participants requiring heart transplantation during follow-up will be assessed.	From SBRT through 36 months after treatment
Incidence of cardiac arrhythmic mortality following SBRT	The number and proportion of participants who die from a cardiac arrhythmic cause during follow-up will be assessed.	From SBRT through 36 months after treatment
Incidence of cardiac non-arrhythmic mortality following SBRT	The number and proportion of participants who die from a cardiac non-arrhythmic cause during follow-up will be assessed.	From SBRT through 36 months after treatment
Incidence and severity of acute radiation-related adverse events	The incidence and severity of adverse events related to radiotherapy will be assessed and graded according to the National Cancer Institute Common Terminology Criteria for Adverse Events (NCI CTCAE), version 5.0. Acute adverse events are defined according to the time period specified in the protocol.	Through 90 days after SBRT
Incidence and severity of late radiation-related adverse events	The incidence and severity of late adverse events related to radiotherapy will be assessed and graded according to NCI CTCAE version 5.0.	The protocol defines late adverse events as those occurring more than 90 days after starting radiotherapy.

Collaborators and Investigators

• Sponsor: Cancer Research Antwerp

Study record dates

Study Major Dates

• Study Start (Actual): February 25, 2026
• Primary Completion (Estimated): February 25, 2032
• Study Completion (Estimated): February 25, 2035

Study Registration Dates

• First Submitted: October 20, 2026
• First Submitted That Met QC Criteria: November 5, 2026
• First Posted (Actual): November 12, 2026

Study Record Updates

• Last Update Posted (Actual): November 12, 2026
• Last Update Submitted That Met QC Criteria: November 5, 2026
• Last Verified: November 1, 2026

More Information

Terms related to this study

• Keywords: SBRT; ventricular tachycardia; electroanatomical mapping; ECG-gated contrast-enhanced CT; 4D-CT simulation
• Additional Relevant MeSH Terms: Cardiac Conduction System Disease; Cardiovascular Diseases; Pathologic Processes; Heart Diseases; Arrhythmias, Cardiac; Tachycardia; Pathological Conditions, Signs and Symptoms; Tachycardia, Ventricular; Investigative Techniques; Therapeutics; Surgical Procedures, Operative; Radiotherapy; Stereotaxic Techniques; Neurosurgical Procedures; Radiosurgery
• Other Study ID Numbers: CTO22012GZA

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No