Ablation-Index Guided Scar-Mediated Ventricular Tachycardia Ablation in Patients With Ischemic Cardiomyopathy

Study Overview
=================
Brief Summary
-----------------
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. The investigators aim at conducting the first randomized controlled trial testing for the superiority of an AI-guided approach regarding procedural duration.

Detailed Description
-----------------
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 CF. 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 humans 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 possibly improve procedural safety in comparison to ablation guided by less reliable conventional parameters or fixed energy application durations. First pilot studies assessing AI-guided VT ablations in patients with structural heart disease provided some observational insights on procedural parameters but our study is the first randomized controlled trial testing for the superiority of an AI-guided approach regarding procedural duration.

Official Title
-----------------
Ablation-Index Guided Scar-Mediated Ventricular Tachycardia Ablation in Patients With Ischemic Cardiomyopathy (AIM-VT) - a Prospective Single-Blinded, Multicenter Randomized Controlled Trial

Conditions
-----------------
Ventricular Tachycardia, Ischemic Cardiomyopathy

Intervention / Treatment
-----------------
* Procedure: Ablation-index guided ventricular tachycardia ablation
* Procedure: Ventricular tachycardia ablation with no AI-guidance


Participation Criteria
=================
Eligibility Criteria
-----------------
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, supraventricular tachycardia, or ventricular fibrillation Myocardial infarction or cardiac surgery within 6 months Severe mitral regurgitation Stroke or TIA within 6 months Prior VT substrate ablation in the previous 6 months NYHA functional class IV Non-ischemic VT substrate

Ages Eligible for Study
-----------------
Minimum Age: 18 Years

Sexes Eligible for Study
-----------------
All

Accepts Healthy Volunteers
-----------------
No

Study Plan
=================
How is the study designed?
-----------------

Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: AI-guided ablation<br>Use of AI guidance to conduct the ablation | Procedure: Ablation-index guided ventricular tachycardia ablation<br>* As described in arms descriptions<br>|
| Active Comparator: non-AI guided ablation<br>Ablation without AI guidance, AI values masked to the operator. | Procedure: Ventricular tachycardia ablation with no AI-guidance<br>* As described in arms descriptions<br>|

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Percentage reduction in ablation time between the groups with/without AI guidance | Percentage of reduction in ablation time in seconds, with ablation time defined as the total radiofrequency delivery time delivered during the VT ablation procedure. Total ablation time is automatically recorded by the Carto System Software and will be subsequently extracted as part of a raw unedited data file for unbiased endpoint evaluation. | intra-procedural | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Percentage of reduction in total procedural duration in seconds between the AI/not AI group | the time elapsed from injection of lidocaine as the start and removal of all catheters from the heart as the end of the procedure. Timestamps logged for these events in the EP lab will be used for unbiased endpoint evaluation. | intra-procedural | 
| Total intravenous fluids administered in milliliters (ml) | Defined as total intravenous fluid volume administered in the EP laboratory | intra-procedural | 
| Fluoroscopy duration in minutes | The time elapsed of procedural fluoroscopy usage in minutes | intra-procedural | 

 Terms related to the study
=================
Keywords Provided by Centre Hospitalier Valida
-----------------
ventricular, tachycardia, ablation index, ischemic cardiomyopathy