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

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:

1. 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.
2. 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.
3. 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.

Study Overview

• Status: Withdrawn
• Conditions: Typical Atrial Flutter
• Intervention / Treatment: Device: Fluoroscopically guided ablation; Device: Contact force guided ablation; Device: Local impedance guide ablation

• Study Type: Interventional
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Karan Saraf, MBChB MRCP(UK); Phone Number: +441612761234; Email: karan.saraf@mft.nhs.uk

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 16 years to 78 years (Adult, Older Adult)
• Accepts Healthy Volunteers: No

Description

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

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

3

Arms and Interventions

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

What is the study measuring?

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

Collaborators and Investigators

• Sponsor: University of Manchester
• Collaborators: Manchester University NHS Foundation Trust

Study record dates

Study Major Dates

• Study Start (Estimated): October 30, 2022
• Primary Completion (Estimated): September 1, 2023
• Study Completion (Estimated): January 1, 2024

Study Registration Dates

• First Submitted: June 10, 2020
• First Submitted That Met QC Criteria: June 15, 2020
• First Posted (Actual): June 17, 2020

Study Record Updates

• Last Update Posted (Actual): November 1, 2023
• Last Update Submitted That Met QC Criteria: October 29, 2023
• Last Verified: October 1, 2023

More Information

Terms related to this study

• Keywords: radiofrequency ablation; contact force; local impedance
• Additional Relevant MeSH Terms: Pathologic Processes; Heart Diseases; Cardiovascular Diseases; Arrhythmias, Cardiac; Atrial Flutter
• Other Study ID Numbers: 281105

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No