This is a multicenter, interventional study. The study will enroll patients that fulfill the inclusion criteria over a 33-month period. Considering the small number of patients who will meet the study criteria, it is also possible to include retrospective patients who already underwent STAR (for instance, as part of a compassionate program) if they meet all the inclusion and exclusion criteria as well as the treatment planning standardized requirements and sign their consent to this trial. All patients prospectively enrolled will undergo a flow of investigations following a standardized approach. ICD programming will be standardized.

Inclusion Criteria:

1. Structural heart disease (SHD) defined as left ventricular dysfunction (LVEF < 55%), or right ventricular dysfunction (FAC <35%) or presence of ventricular scar, pathological hypertrophy, wall bulging or inflammatory conditions.
2. Optimized medical treatment for the underlying SHD
3. ICD or CRT-D recipient
4. ≥ 1 episodes of sustained or treated (with either anti-tachycardia pacing or shock, internal or external) monomorphic VT (MMVT) resistant to at least one invasive VT ablation attempt, unless contraindicated or deemed at high risk. Reason for lack of ablation must be specified

Exclusion Criteria:

1. Age < 18 or > 85 years.
2. Inability to provide informed consent.
3. Acute myocardial infarction or recent primary coronary intervention or cardiac surgery (<3 months)
4. Primary electrical disease (e.g. long QT syndrome, short QT syndrome, catecholaminergic polymorphic ventricular tachycardia, Brugada syndrome).
5. Reversible and/or treatable cause of VT (e.g., drug-induced or intoxication)
6. ICD electrode malfunction or ICD readings outside reference range
7. Pregnancy or breast feeding
8. Patients with polymorphic VT/VF