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

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

Overview

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.

Interventions

• Procedure Ablation-index guided ventricular tachycardia ablation
  As described in arms descriptions
• Procedure Ventricular tachycardia ablation with no AI-guidance
  As described in arms descriptions

Primary outcome measures

• Percentage reduction in ablation time between the groups with/without AI guidance [Time frame: intra-procedural]

Secondary outcome measures (3)

• Percentage of reduction in total procedural duration in seconds between the AI/not AI group [Time frame: intra-procedural]
• Total intravenous fluids administered in milliliters (ml) [Time frame: intra-procedural]
• Fluoroscopy duration in minutes [Time frame: intra-procedural]

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

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: No

Study design

Allocation

Randomized

Model

Parallel assignment

Masking

Triple blind

Primary purpose

Treatment

Study locations

United States · 5 centers

• Rush University Medical Center — Chicago
• Mass General Brigham and Women's Hospital — Boston
• Medical University of Michigan — Ann Arbor
• Mayo Clinic — Rochester
• Medical University of South Carolina — Charleston

Publications

• Proietti R, Lichelli L, Lellouche N, Dhanjal T. The challenge of optimising ablation lesions in catheter ablation of ventricular tachycardia. J Arrhythm. 2020 Dec 28;37(1):140-147. doi: 10.1002/joa3.12489. eCollection 2021 Feb. PMID 33664896
• Larsen T, Du-Fay-de-Lavallaz JM, Winterfield JR, Ravi V, Rhodes P, Wasserlauf J, Trohman RG, Sharma PS, Huang HD. Comparison of ablation index versus time-guided radiofrequency energy dosing using normal and half-normal saline irrigation in a porcine left ventricular model. J Cardiovasc Electrophysiol. 2022 Apr;33(4):698-712. doi: 10.1111/jce.15379. Epub 2022 Jan 30. PMID 35048448
• Hussein A, Das M, Riva S, Morgan M, Ronayne C, Sahni A, Shaw M, Todd D, Hall M, Modi S, Natale A, Dello Russo A, Snowdon R, Gupta D. Use of Ablation Index-Guided Ablation Results in High Rates of Durable Pulmonary Vein Isolation and Freedom From Arrhythmia in Persistent Atrial Fibrillation Patients: The PRAISE Study Results. Circ Arrhythm Electrophysiol. 2018 Sep;11(9):e006576. doi: 10.1161/CIRCEP PMID 30354288
• Gasperetti A, Sicuso R, Dello Russo A, Zucchelli G, Saguner AM, Notarstefano P, Soldati E, Bongiorni MG, Della Rocca DG, Mohanty S, Carbucicchio C, Duru F, Di Biase L, Natale A, Tondo C, Casella M. Prospective use of ablation index for the ablation of right ventricle outflow tract premature ventricular contractions: a proof of concept study. Europace. 2021 Jan 27;23(1):91-98. doi: 10.1093/europace PMID 33063099
• Bates AP, Paisey J, Yue A, Banks P, Roberts PR, Ullah W. Radiofrequency Ablation of the Diseased Human Left Ventricle: Biophysical and Electrogram-Based Analysis. JACC Clin Electrophysiol. 2023 Mar;9(3):330-340. doi: 10.1016/j.jacep.2022.10.001. Epub 2022 Oct 10. PMID 36371330

Identifiers

NCT: NCT06138873 · AIM-VT

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗