Multimodality Assessment of Ventricular Scar Arrhythmogenicity.

Patients will be eligible for this trial both from referrals as an outpatient, where VT has been detected on a heart rhythm monitor or ECG (electrical heart tracing), or as an inpatient where they have been admitted to hospital with symptoms of VT. Our study investigators will discuss the research with the patient and give them the relevant information in an understandable format as part of a Patient Information Sheet so that they can make an informed decision about whether or not to participate in the research.

An MRI scan of the heart is a standard investigation for patients presenting with VT, however if the patient is included in the study, the MRI scan images will be anonymised and sent confidentially to the Institute of Computational Modelling at Johns Hopkins University in USA where the images will be reconstructed into a 3D representation of the patients heart, where the electrical pathways and source of the VT can be seen. This information will be sent back (again confidentially and anonymously) to St George's Hospital in time for their routine VT ablation procedure.

During the VT ablation The MRI scan model will be combined with the invasively-obtained information and we will assess the various areas of the heart which are responsible for the VT, particularly relating to areas of scar within the heart, which are frequently seen in these patients. We will assess the electrical properties of the areas highlighted as the cause of the VT from the MRI scan.

We will assess the accuracy of the computer model compared to the traditional invasive measurements that we take. We will first ablate those areas of the heart which the model predicted as being important (as long as the invasive characteristics support ablation there) and then see what effect this had on the electrical properties of other areas of the heart. However, we will not ablate any area of the heart based solely on the MRI model; it will only influence the order of ablation and not tell us whether to ablate or not.

The procedure can take 4-6 hours in total. The extra information gathered as part of the research protocol may extend this by a maximum of 10%. No extra pieces of equipment, procedures or medications are involved in the research, just the time taken to generate a computer model of the heart as well as a extra time to assess the heart in more detail during the ablation.

Following the ablation, the patients will be followed at 3, 6 and 12 months with a heart rhythm monitor and a clinical review as an outpatient as per routine standard of care. From this, we will collect data on frequency of recurrence of rhythm disturbance, therapy from their implantable cardioverter-defibrillators, symptoms and complications following the ablation procedure.

The information gathered during the procedure will be analysed and research papers generated from the results.

Inclusion criteria

Adult inpatients admitted to St George's Hospital London with sustained ventricular tachycardia or outpatients identified from the arrhythmia clinic with significant monomorphic ventricular tachycardia noted on cardiac monitoring who:

• Have sustained, monomorphic scar-dependent ventricular tachycardia
• Are symptomatic
• Failed, unable or unwilling to tolerate anti-arrhythmic medications
• Able to have a cardiac MRI
• Have a life expectancy > 1 year
• At least 40 days following a myocardial infarction

Exclusion criteria

• Patients under the age of 18
• Patients who are unable to give informed consent
• Pregnant patients
• Unable to have cardiac MRI
• Prohibitive procedural risk
• Unable to tolerate the ablation procedure due to haemodynamic instability