Stereotactic Radioablation as First-Line Therapy for Scar-Related Ventricular Tachycardia

Ventricular tachycardia (VT) is a dangerous fast heart rhythm originating from scarred areas of the heart muscle, often after a heart attack or in patients with cardiomyopathy. Patients with VT and structural heart disease typically receive an implantable cardioverter-defibrillator (ICD) to prevent sudden death. Despite the ICD, recurrent VT and ICD shocks remain common and are associated with poor quality of life. Current preventive therapies - antiarrhythmic medications and catheter radiofrequency ablation - have important limitations including side effects, incomplete effectiveness, and procedural risk.

Stereotactic Arrhythmia Radioablation (STAR) is a non-invasive treatment in which a single, precisely targeted dose of radiation is delivered to the scar tissue that gives rise to the abnormal heart rhythm. STAR has previously been studied in patients who have failed catheter ablation or are too high risk for that procedure, with promising results. However, STAR has not been formally evaluated as a first-line treatment.

This single-arm prospective feasibility study will enroll 20 adults with structural heart disease and sustained monomorphic VT. Each participant will receive a single 25 Gy fraction of stereotactic body radiotherapy (VMAT technique) targeted at the arrhythmogenic substrate identified by cardiac imaging, 12-lead ECG, and (where available) non-invasive electrocardiographic mapping or electroanatomical mapping. Participants will be followed at 6 weeks, 3, 6, 9, and 12 months to assess the primary efficacy outcomes (death, appropriate ICD shock, VT storm, and sustained VT below ICD detection rate after a 6-week blanking period) and safety outcomes (acute heart failure decompensation, drop in left ventricular ejection fraction, and STAR-specific toxicities such as pneumonitis, esophagitis, and pericarditis). The hypothesis is that STAR delivered as first-line therapy is safe and effective, with a comparable toxicity and efficacy profile to catheter radiofrequency ablation.