Ablation-Index Guided Ventricular Tachycardia Ablations

Study Overview
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Brief Summary
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Over the last decade, radiofrequency catheter ablation (RFCA) has become an established treatment for ventricular arrhythmias (VA). Due to the challenging nature of visualizing lesion formation in real time and ensuring an effective transmural lesion, different surrogate measures of lesion quality have been used. The Ablation Index (AI) is a variable incorporating power delivery in its formula and combining it with CF and time in a weighted equation which aims at allowing for a more precise estimation of lesion depth and quality when ablating VAs. AI guidance has previously been shown to improve outcomes in atrial and ventricular ablation in patients with premature ventricular complexes (PVC). However research on outcomes following AI-guidance for VT ablation specifically in patients with structural disease and prior myocardial infarction remains sparse. We aim at conducting a prospective observational multicenter registry investigating the efficacy and safety of AI-guided VA ablation in patient with ischemic and non-ischemic cardiomyopathy.

Detailed Description
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Over the last decade, radiofrequency catheter ablation (RFCA) has become an established treatment for ventricular arrhythmias (VA). RFCA uses electromagnetic energy that transforms into heat upon delivery into the myocardium and irreversibly damages the viable myocytes, causing the loss of cellular excitability. Irreversible loss of cellular excitability generally occurs at temperatures exceeding 50°C, while at lower temperatures, the damage is not permanent and myocytes can recover excitability, leading to VA recurrences. Due to the challenging nature of visualizing lesion formation in real time and ensuring an effective transmural lesion, different surrogate measures of lesion quality have been used. The fall in local impedance during ablation has been considered as a first marker of the direct effect of ablation in cardiac tissue but the generator impedance drop does not correlate well with lesion size. First, large impedance drops can indicate impeding steam pop without effective lesion formation. Second scar tissue carries a lower impedance than healthy tissue due to their higher water/collagen content and make impedance drops less reliable. One of the major determinants of lesion formation is an adequate contact between the tip of the catheter and the myocardial surface. A first major technological advancement in ablation catheters was the development of sensors at the distal tip capable of monitoring contact (contact force, CF). A recent ablation marker is the Force-Time-Integral (FTI), which multiplies CF by radiofrequency application duration. Limitations in this ablation parameter are the exclusion of maximal power settings being delivered and the assumption that a single target FTI is required in all myocardial segments with varying wall thickness and underlying substrate. Also for prolonged energy deliveries, the contribution of radiofrequency application duration is proportionally less important in lesion creation than CF1. To overcome some of these limitations, the Ablation Index (AI) was introduced. This is a variable incorporating power delivery in its formula and combining it with CF and time in a weighted equation. It has shown to be a more precise estimation of lesion depth and quality in animal models and humans1 than FTI, time alone or impedance drop. AI guidance has previously been shown to improve outcomes in atrial and ventricular ablation in patients with premature ventricular complexes (PVC). However research on outcomes following AI-guidance for VT ablation specifically in patients with structural disease and prior myocardial infarction remains sparse, with mainly research conducted in ex-vivo porcine or canine models. In theory, use of AI to guide ablation in this subpopulation of VT patients may shorten procedure time and improve procedural safety in comparison to ablation guided by less reliable conventional parameters or fixed energy application durations. The available research assessing AI-guided VT ablations in patients with structural heart diseased focused on procedural parameters and did not deliver any clinically/prognostic relevant data. While there has been a technological advancement in the monitoring and titration of energy delivered to yield effective RF lesion formation, the application of these tools have been scarcely investigated and implemented in the practice of VT ablation. Since VT recurrence in patients treated with RFCA can be related, at least partly, to inadequate RF lesion formation, it is imperative to continue to explore the need for robust, transferrable markers of ablation efficacy. Further, longer procedure time and time under general anesthesia during VT ablation procedures have been associated with higher procedural morbidity. Thus, a means of concurrently shortening procedure time while maintaining clinical effectiveness may together improve overall outcomes in patients with structural heart disease who undergo VT ablation. The present study will aim at clarifying the efficacy and safety of one of these markers of ablation efficacy, the ablation-index, in a large cohort of patients undergoing VA, thereby providing the first long-term registry on this particular ablation procedure.

Official Title
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Ablation-Index Guided Ventricular Tachycardia Ablation in Patients With Ischemic Cardiomyopathy - a Prospective, Multicenter Registry.

Conditions
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Ventricular Tachycardia, Ventricular Arrythmia, Cardiomyopathies

Intervention / Treatment
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* Device: AI-guided VA ablation


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patient ≥ 18 y.o. Structural Heart Disease: Ischemic Cardiomyopathy Sustained Scar-related Monomorphic Ventricular Tachycardia documented by ECG or CIED interrogation Exclusion Criteria: If clinical ventricular arrhythmia is predominantly PVCs, polymorphic ventricular tachycardia, or ventricular fibrillation Myocardial infarction or Cardiac Surgery within 6 months Severe mitral regurgitation Stroke or TIA within 6 months Prior Ventricular Tachycardia Ablation

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| AI-guided VA ablation<br>This is a prospective observational multicenter registry. Patients presenting for a VT ablation at Rush will be screened for inclusion/exclusion criteria and will be included in the study appropriately. The EP specialist conducting the ablation and/or the electrophysiology fellows involved in the procedure will be responsible for patients screening and inclusion. Further data completion (pre-ablation diagnostic procedures, baseline characteristics, ablation data, periprocedural period before discharge home) will be extracted from EPIC and from the study center's Cardiac Mapping System's hard drive. Follow-up data will be collected from any in-person and virtual clinic visits as per standard of care within 12 months after the index ablation procedure. Follow-up data will also be collected by chart review from routine in-person and remote device interrogations of their ICD devices also conducted as standard of care. | Device: AI-guided VA ablation<br>* Ablation of ventricular arrhythmia as guided by the ablation index, using Carto 3 electroanatomic mapping system, QDOT Micro ablation catheter, and multipolar mapping catheters (Optrell, Decanav)<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Procedure duration | Total duration of the procedure from injection of lidocaine to removal of sheaths | intra-procedural | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Fluoroscopy time | Total fluoroscopy time of the procedure | intra-procedural | 
| Number of RF applications | Median/mean number of RF applications used per patient during the procedure | intra-procedural | 
| Total RF duration | Total duration of radiofrequency ablation during the procedure | intra-procedural | 
| Average RF time per lesion | Average duration of radiofrequency application per lesion | intra-procedural | 
| Ablation index per lesion | Average ablation index per lesion | intra-procedural | 
| Impedance drop from baseline per lesion | Average of the impedance drop from baseline for each lesion | intra-procedural | 
| Acute procedural success | Acute freedom from VT (non-inducibility of clinical VT, non-inducibility of any VT, elimination of late potentials and each component separately) | intra-procedural | 
| Complications (composite) | Rate of complications within 7 days after procedure of a composite safety outcome including bleeding (major and minor), death, pericardial effusion, cardiac tamponade, stroke, arterial thromboembolism, steam pops, thrombus formation, cardiogenic shock, phrenic nerve paralysis, congestive heart failure | 7 days | 
| Complications (single elements) | Rate of complications within 7 days after procedure of a components of a safety outcome including bleeding (major and minor), death, pericardial effusion, cardiac tamponade, stroke, arterial thromboembolism, steam pops, thrombus formation, cardiogenic shock, phrenic nerve paralysis, congestive heart failure | 7 days | 
| Recurrence of Sustained Ventricular Tachycardia or ICD therapy | Recurrence of a sustained VT or need for ICD therapy up to 1 year (time-to-failure analysis as well as cumulative analysis) | 1 year | 
| Hospitalization for Ventricular Tachycardia | Hospitalization for Ventricular Tachycardia up to 1 year (time-to-failure analysis as well as cumulative analysis) | 1 year | 
| Outcome of death after ablation procedure from cardiovascular or non-cardiovascular cause | Overall death up to 1-year (cardiovascular and non-cardiovascular as well as single components separately) | 1 year | 
| Outcome of repeat ablation procedure for sustained ventricular tachycardia or appropriate ICD therapy after index ventricular tachycardia ablation procedure | Outcome of repeat ablation procedure for sustained ventricular tachycardia or appropriate ICD therapy after index ventricular tachycardia ablation procedure at 1 year (time-to-failure analysis as well as cumulative analysis) | 1 year | 
| Drug prescription pattern | Prescription pattern of anti-arrhythmic drugs (amiodarone, sotalol, mexilitene, quinidine, disopyramide) before and after ablation in the cohort | 1 year | 
| Feasibility of AI-guided ablation (objective) | Assessment of the number of applied lesions failing protocol restrictions of an AI cut-off of 550 ± 55 (10% variation allowed) | intra-procedural | 
| Feasibility of AI-guided ablation (subjective) | Assessment of proceduralist comfort and learning curve through repeating surveys after 10, 25 procedures | intra-procedural | 
| Numerical AI differences in patients experiencing a VT recurrence in the follow-up versus patients not experiencing any recurrences | Median, maximal, minimal and median of the maximal AI applications in patients experience or not a VT recurrence in the follow-up | 1 year | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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ventricular, arrythmia, fibrillation, ventricular tachycardia, cardiomyopathy, ablation, ablation index