Ventricular tachycardia (VT) is an abnormal rapid heartbeat which occurs after a heart attack and can cause sudden death. Patients at risk of this rhythm disturbance usually receive an implantable cardioverter defibrillator (ICD) that can prevent death by returning the heart's rhythm back to normal by electrically stimulating the heart but in doing so gives the patient painful and debilitating shocks. The first ICD shock after implantation appears to be a powerful predictor of subsequent shock therapy as well as being a predictor of of increased mortality in patients with primary prevention ICDs. In patients who receive repeated shocks VT ablation is performed to 'burn' the abnormal area of the heart that causes the problem. However, it is often only performed as a last resort as it is technically challenging. We believe that performing VT ablation using the robotic system early after the first episode of VT after ICD implantation, may reduce the number of painful shocks received by the patient and possibly increase life expectancy and quality of life.

200 patients from 5 european countries will be recruited in a prospective, open, randomised trial. Eligible, consenting patients who have experienced their first episode of VT since ICD implantation, will be randomised in a 1:1 manner into treatment arms of either VT ablation or standard 'conventional' therapy and followed-up every 4 months over two years to assess the number of subsequent ICD shocks, hospitalisation, mortality and quality of life.

Inclusion Criteria:

• Males or females eighteen (18) to eighty-five (85) years old
• ICD implantation for post-infarct primary or secondary prophylaxis
• First episode of VT detected (within monitor zone or therapy (ATP /shock delivered) or by 12 lead ECG if the rate below the detection level of the device.
• Suitable candidate for catheter ablation
• Signed informed consent

Exclusion Criteria:

• Contraindication to catheter ablation
• Ventricular tachycardia due to transient, reversible causes
• Presence of a left ventricular thrombus
• Severe cerebrovascular disease
• Active gastrointestinal bleeding
• Renal failure (on dialysis or at risk of requiring dialysis)
• Active infection or fever
• Life expectancy shorter than the duration of the trial
• Allergy to contrast
• Intractable heart failure (NYHA Class IV)
• Bleeding or clotting disorders or inability to receive heparin
• Serum [K+] <3.5 or >5.0mmol/L
• Serum Creatinine >200umol/L
• Uncontrolled diabetes (HbA1c ≥73mmol/mol or HbA1c ≤64mmol/mol and Fasting Blood Glucose ≥9.2mmol/L)
• Malignancy needing therapy
• Pregnancy or women of child-bearing potential not using a highly effective method of contraception
• Unable to give informed consent
• Unable to attend follow-up in ICD clinics