Multimodality Assessment of Ventricular Scar Arrhythmogenicity.

Study Overview
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Brief Summary
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We aim to improve our understanding of a life-threatening heart rhythm disorder known as ventricular tachycardia (VT). This is a disorder which originates from the lower chamber of the heart and frequently is associated with heart disease. We will use an MRI scan to generate a computer based model of the heart which can predict areas of the heart which are important in generating this rhythm disorder. We intend to assess how accurate this computer model is compared to traditional invasive assessment of the heart muscle. We also aim to assess the electrical characteristics of those areas which were predicted by the computer model in order to see why they were thought to be so important. All patients seen at St George's Hospital with VT will be eligible. As is routine for these patients, they will have an MRI scan of the heart. We will then use this scan to create a virtual reconstruction of the heart from which predictions of the critical areas of the heart which are generating the rhythm problem will be made. Then we will perform a VT ablation (studying the electrical properties and if necessary making a burn to treat the rhythm problem) - as per standard of care, however during the ablation we will spend extra time collecting information comparing the accuracy of the computer-generated model to the traditional invasive signals which guide ablation. We will study the electrical properties of those predicted areas to see what is special about them. The study will last up to three years.

Detailed Description
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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.

Official Title
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Can MRI-based Computational Modelling of the Heart be Used to Predict Critical Substrate in Scar-dependent Ventricular Tachycardia Ablation?

Conditions
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Ventricular Tachycardia

Intervention / Treatment
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* Diagnostic Test: Generation of computational model from cardiac MRI.
* Procedure: VT ablation


Participation Criteria
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Eligibility Criteria
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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

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Cases<br>Patients with scar-dependent ventricular tachycardia, requiring ablation. These patients will have satisfied the inclusion/exclusion criteria and be put forward for VT ablation. They will undergo the previously described study protocol, including generation of a computational model of the heart from their cardiac MRI and a VT ablation where we will study the points of interest generated from the MRI model in detail. | Diagnostic Test: Generation of computational model from cardiac MRI.<br>* Routine cardiac MRI scan results will be sent to Johns Hopkins University where a computer-generated model of the heart will be made, which will demonstrate predicted areas critical to VT generation and maintenance. This data will be sent back to St George's, and integrated with the standard VT ablation mapping software to allow comparison of its accuracy with standard mapping techniques.<br>Procedure: VT ablation<br>* Routine VT ablation as described elsewhere in the literature. However, a brief period of extra time ( 30 minutes) will be spent analysing the areas of the heart which the MRI scan predicted as being important for generation of VT. We will study the effect of ablation of these areas (if indicated) on distant parts of the heart.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Assessment of the degree of validation of in silico computational modelling by invasive ventricular scar interrogation | Assessment of the degree of validation of in silico computational modelling by invasive ventricular scar interrogation to see if the predicted sites match those sites which would have been determined as important from invasive mapping. | During ablation | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Qualification of the electrophysiological characteristics of those sites which the computational model predicted | Qualification of the electrophysiological characteristics of those sites which the computational model predicted in an attempt to see what it is about them that makes them likely to be key to maintaining the arrhythmia. With our mapping techniques, we can assess not only the amplitude and morphology of the electrograms from these areas, but also the directionality of wavefronts to see if this is an important feature. With the additional benefit of the 3D computational model, we may be able to gain some insight into the 3D nature of channels which form part of the VT substrate. | During ablation | 
| Assessment of the change in the invasive electrophysiological characteristics of distant sites following ablation of the predicted in silico sites | Assessment of the change in the invasive electrophysiological characteristics of distant sites following ablation of the predicted in silico sites. | During ablation | 
| Rhythm assessment at 3, 6 and 12 months. | Assessment of the frequency of ventricular arrhythmia as detected by 24 hour ECG monitors (or from implantable cardioverter-defibrillator (ICD), if applicable) at 3, 6 and 12 months | 12 months | 
| Symptom assessment at 12 month clinical follow up | Assessment of patient's symptoms at a clinical consultation following the ablation. | 12 months | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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ventricular tachycardia, ablation, cardiac MRI, computational modelling