Ventricular tachycardia (VT) is a life-threatening heart rhythm disorder and one of the commonest causes of heart-related sudden death. It often affects people who have had a heart attack or other structural heart damage. VT occurs when abnormal electrical circuits develop within and around scar tissue in the heart.

People at risk are usually offered an implantable cardiac defibrillator (ICD), a device that can detect VT and deliver a lifesaving shock. While effective, these shocks can be sudden, painful and distressing. Medications such as amiodarone can also help, but they are often unsuitable for long-term use due to their potential side effects on the liver, lungs and thyroid gland.

An alternative is catheter ablation. Thin tubes (catheters) are threaded from a blood vessel in the groin to the heart, allowing the cardiologist to identify scar tissue and abnormal electrical circuits, which can be destroyed using heat, freezing or electrical energy.

Although ablation can help many patients, VT can return in up to one in three people after the procedure. This is because it can be difficult to precisely identify the scar and surrounding tissue that sustain the abnormal circuits, making it challenging to know exactly where to apply ablation treatment.

Dynamic Voltage Mapping, is a technique which the investigators believe can more accurately identify scar and the critical bordering tissue during ablation. Initial data collected suggests that the approach accurately predicts the VT circuit and helps guide ablation.

In this study, the investigators wish to recruit 40 participants undergoing VT ablation to determine how effective Dynamic Voltage Mapping is in real-world procedures.

Inclusion Criteria:

• Scheduled for clinically indicated VT ablation (due to sustained VT episodes or ICD therapies).
• Willing and able to give informed consent for participation in the trial
• Male or female aged between 18-85
• Ischaemic and non-ischaemic cardiomyopathy
• ICD insitu

Exclusion Criteria:

• Unable or unwilling to consent
• NYHA Class IV (end stage heart failure)
• Metastatic cancer
• End stage renal disease
• Pregnant or breast feeding
• Severe frailty

De-identified individual participant data underlying the results reported in publications (including baseline characteristics, procedural data, and outcome measures). Additional data may be available upon reasonable request, subject to institutional approvals and data sharing agreements.

IPD and supporting information will be available beginning 6 months after publication of the primary results and will remain available for 5 years thereafter.

De-identified individual participant data and supporting documents (study protocol, statistical analysis plan, and analytic code) will be available to qualified researchers for scientifically sound proposals. Access will be granted upon reasonable request to the study's Chief Investigator, subject to review and approval by the sponsor and in accordance with institutional and regulatory requirements. Data will be shared under a formal data sharing agreement, and access will be provided via a secure data transfer method or controlled-access environment.