Fluoroscopic, Contact Force and Local Impedance With Ultra-high Density Mapping Guided Radiofrequency Ablation Comparison for cavoTricuspid Isthmus dependenT Atrial fluttER: the FLUTTER Study

Study Overview
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Brief Summary
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Catheter ablation is a first-line treatment for patients with cavotricuspid isthmus (CTI) dependent atrial flutter (AFL; also known as typical AFL), a common arrhythmia. This is done using radiofrequency (RF) catheters and single-procedure success is approximately 95%. Ablation is often done using one of three methods: fluoroscopically, using X-rays to guide the operator to visualise catheter position within the heart. This method involves the most radiation exposure to patient and operator. Ablation is generally performed for a set time-period (eg. 30-60secs) to ensure each ablation lesion is successful. using a 3-dimensional mapping system which allows the catheters to be magnetically located and visualised on a monitor without X-rays, and using contact force (CF) sensing catheters. This requires minimal X-ray use, and by ensuring a minimum degree of force between catheter tip and the heart before applying RF for a set time-period (eg. 30 seconds), operators can be more confident of successful lesions. using an ultra-high density mapping system which uses magnetic tracking as above, but allows higher resolution visualisation of the cardiac electrical system with potential for improving procedure success; this has not yet been formally evaluated for AFL. Catheters using this method use local impedance (LI) instead of CF. This is a direct measure of heart tissue impedance with real-time changes during ablation. A minimum drop or plateau in the LI value during ablation allows confidence of lesion success, without the need to ablate for a pre-defined time-period. This could potentially reduce ablation time and subsequent complications, but has also not yet been formally compared to the above for this indication. This prospective randomised study aims to compare these three standard of care procedures to determine if differences in ablation metrics, efficacy and safety exist.

Official Title
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Fluoroscopic, Contact Force and Local Impedance With Ultra-high Density Mapping Guided Radiofrequency Ablation Comparison for cavoTricuspid Isthmus dependenT Atrial fluttER: the FLUTTER Study

Conditions
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Typical Atrial Flutter

Intervention / Treatment
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* Device: Fluoroscopically guided ablation
* Device: Contact force guided ablation
* Device: Local impedance guide ablation


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patients under the care of the NHS Aged 18-80 years Symptoms and 12-lead ECG suggestive of typical (cavotricuspid isthmus dependent) atrial flutter Due to undergo first-time cavotricuspid isthmus ablation (including as part of a combined ablation if also having pulmonary vein isolation for atrial fibrillation) on clinical grounds Exclusion Criteria: Pre-procedure: Inability to given informed consent / lack of mental capacity Obesity (BMI >40) Congenital heart disease or tricuspid valve abnormalities likely to prolong procedure time, including Ebstein anomaly, atrial septal defects, tricuspid valve repair or replacement, severe tricuspid valve regurgitation Inability or unwillingness to receive oral anticoagulation with a vitamin K antagonist (VKA) or non-VKA oral anticoagulant (NOAC) Previous cavotricuspid isthmus ablation procedure Known infiltrative cardiomyopathy Pregnancy Age < 18 or >80 Inability to speak adequate English/need for an interpreter for study consent process Post procedure: - arrhythmia mechanism found not to be cavotricuspid isthmus dependent atrial flutter

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 80 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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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Interventional Model Description: 114 patients randomised 1:1:1 to either fluoroscopically guided OR contact force guided OR local impedance guided radiofrequency catheter ablation of typical atrial flutter
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Fluoroscopically guided ablation<br>These patients will receive one catheter ablation of typical atrial flutter by fluoroscopically guided radiofrequency ablation catheters | Device: Fluoroscopically guided ablation<br>* Catheter ablation of the cavotricuspid isthmus using ablation catheters guided by fluoroscopy<br>|
| Active Comparator: Contact force guided ablation<br>These patients will receive one catheter ablation of typical atrial flutter by contact force guided radiofrequency ablation catheters using the CARTO 3D electroanatomic mapping system | Device: Contact force guided ablation<br>* Catheter ablation of the cavotricuspid isthmus using ablation catheters guided by contact force measurement and 3D electroanatomic mapping<br>|
| Active Comparator: Local impedance guided ablation<br>These patients will receive one catheter ablation of typical atrial flutter by local impedence guided radiofrequency ablation catheters using the Rhythmia Ultra-high density 3D electroanatomic mapping system | Device: Local impedance guide ablation<br>* Catheter ablation of the cavotricuspid isthmus using ablation catheters guided by local impedance measurement and ultra-high density 3D electroanatomic mapping<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Time from first application of radiofrequency energy to confirmation of bidirectional cavotricuspid isthmus block | Time from first application of radiofrequency energy to confirmation of bidirectional cavotricuspid isthmus block | At time of procedure | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Mean total ablation time to achieve bidirectional cavotricuspid isthmus block | Mean total ablation time to achieve bidirectional cavotricuspid isthmus block | At time of procedure | 
| Mean total radiation exposure | Mean total radiation exposure | At time of procedure | 
| Mean total number of ablation lesions required to achieve bidirectional cavotricuspid isthmus block | Mean total number of ablation lesions required to achieve bidirectional cavotricuspid isthmus block | At time of procedure | 
| Number of cases where bidirectional cavotricuspid isthmus block was not achieved after the first pass of ablation | Number of cases where bidirectional cavotricuspid isthmus block was not achieved after the first pass of ablation | At time of procedure | 
| Mean time taken for second pass ablation (with or without the use of 3D mapping) to achieve bidirectional cavotricuspid isthmus block | Mean time taken for second pass ablation (with or without the use of 3D mapping) to achieve bidirectional cavotricuspid isthmus block | At time of procedure | 
| Locations of breakthrough across the initial ablation line | Locations of breakthrough across the initial ablation line | At time of procedure | 
| Frequency of procedural complications | Frequency of procedural complications | At time of and immediately following procedure | 
| Acute and medium-term success rates | Acute and medium-term success rates | 12 months | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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radiofrequency ablation, contact force, local impedance