The goal of this randomized clinical trial is to test the efficacy of stereotactic body radiation therapy (SBRT) in treating ventricular tachycardia (VT) in patients with advanced structural heart disease. The main questions it aims to answer are:

• What is the efficacy of SBRT compared to catheter ablation (CA) in achieving a ≥ 75% reduction in VT burden at 6 months
• What is the comparable safety profile of SBRT vs CA Researchers will compare SBRT and CA (standard of care).

Hypothesis

We hypothesise that in an open label randomised controlled trial of patients with advanced structural heart disease and ventricular tachycardia (VT) that stereotactic body radiation therapy (SBRT) will be superior in reducing VT burden compared to standard care comprising of catheter ablation (CA) and routine medical care with acceptable safety and adverse events.

Aims

This is a trial to examine if in an open label randomised trial of 60 patients with structural heart disease and VT followed for 3 years with a minimum follow up of 1 year of SBRT compared CA results in:

1. An improvement in a primary outcome of proportion of patients with a ≥75% reduction in VT burden in the 6 months following intervention compared to the 6 months intervention
2. Comparable safety profile (serious adverse events [SAE] and adverse events of special interest [AESI] at 6 months;
3. reduction in secondary endpoints at 6, 12, 24 and 36 months of: any VT recurrence, absolute % reduction in VT burden compared to 6 months pre-treatment, number of anti-arrhythmic drugs (AADs) compared to pre-treatment, cardiovascular hospitalisation, all-cause mortality, cardiac transplantation, combined endpoint of cardiovascular hospitalisation/transplant/mortality, SAE and AESI from treatment, ventricular function abd change of quality of life (QOL) metrics (at 12 months).

Inclusion Criteria:

1. Structural heart disease (including ischaemic cardiomyopathy , non-ischaemic cardiomyopathy or congenital heart disease and defined as any one of

   1. segmental or global decreased ventricular wall motion as defined by TTE, CT or cMRI
   2. myocardial hypertrophy
   3. myocardial scar (evidenced by late gadolinium enhancement on cMRI, wall thinning on cardiac CT, low voltage on electrophysiological study or abnormal intracardiac echocardiography)

2. Recurrent monomorphic VT which can include

   1. at least one episode of VT treated by ICD and/or
   2. sustained VT (lasting >30s) and/or
   3. inducible sustained VT on invasive electrophysiological study (EPS) or non-invasive programmed stimulation (NIPS)

3. PAINESD score of ≥9 points and/or at least moderate risk of VT recurrence or death as defined by the I-VT score. Both are validated tools used clinically to identify patient at high risk of VT recurrence and/or mortality after CA.

Exclusion Criteria:

1. Age < 18 years
2. Life expectancy < 3 months
3. Catheter ablation deemed futile or with prohibitive risk by cardiac electrophysiologist.
4. Unwilling or unable to provide consent
5. Known cardiac channelopathies (e.g. Catecholaminergic polymorphic ventricular tachycardia (CPVT), long- or short QT syndrome, Brugada syndrome)
6. Contraindications to radiotherapy as deemed by referring physician and/or radiation oncologist
7. Pregnancy or breast feeding