Characterising the Stable and Dynamic Left Atrial Substrate in Atrial Fibrillation

NCT04229472 | Completed Results

• 1 other identifier: 14295
• Study Type: interventional
• Target: 31
• Locations: 1 country
• Sites: 1

Brief Summary

Atrial fibrillation (AF) is the most common sustained arrhythmia, with increasing prevalence associated with an ageing population. Management is challenging, and invasive catheter ablation procedures are increasingly used in those with symptoms refractory to drug therapy. Unfortunately, success rates from this procedure can be limited. This is partly due to limitations in understanding of the mechanisms involved in arrhythmia propagation. There is much interest in the role of structural changes within the muscle of the left atrium resulting in scaring (known as fibrosis). This has been identified on MRI studies and invasive electroanatomical mapping using voltage amplitude of recorded signals as a surrogate measure of tissue properties. This however is affected by the technology used, as it does not routinely incorporate the effect of heart rate on conduction properties. Furthermore, although this aims to identify regions of structural changes, it does not identify more dynamic patterns of conduction seen during AF. This study aims to use a high density mapping catheter (Abbott Advisa HD grid (SE)), which employs a novel algorithm to minimise the effect of wavefront direction on the size of electrical signals. Electroanatomical mapping of the left atrium in patients with atrial fibrillation will be conducted whilst pacing at long and short cycle lengths to assess the effect of pacing rate on conduction properties, assessed using signal morphology and conduction velocity. The same procedure will also be carried out in 5 control patients to allow comparison with normal atria. Two subgroups will also analysed. In the first the aim is to compare the use of the HD grid catheter to a bipolar ablation catheter in carrying out electroanatomical mapping. In the second, to correlate electrical signals obtained with propagation patterns identified using the AcQMap non-contact mapping system and atrial properties identified on cardiac MRI.

Conditions

Atrial Fibrillation

Outcome Measures

Primary Outcomes (1)

• To Define the Normal Range of Voltage Amplitude

  Mean and distribution of left atrial voltage amplitude across the whole chamber and by segments with lower limit of normal defined as the upper 95% value within the segment with the lowest mean amplitude at long pacing cycle length.

  During ablation procedure

Secondary Outcomes (6)

• Effect of Pacing Cycle Length on Electrogram Morphology

  During ablation procedure

• Effect of Pacing Cycle Length on Conduction Velocity

  During ablation procedure

• To Compare Electroanatomic Voltage Mapping (EAVM) Performed With a Bipolar Contact Force Guided Ablation Catheter to the Abbott HD Grid Using Orthogonal Wave Analysis in Sinus Rhythm.

  During ablation procedure

• To Evaluate the Distribution of Late Gadolinium Enhancement on Cardiac MRI Relative to Electrogram Amplitude Identified Using the HD Grid

  During ablation procedure

• To Evaluate the Distribution of Electrogram Morphologies Relative to Late Gadolinium Enhancement on Cardiac MRI

  During ablation procedure

Other Outcomes (3)

• Evaluate the Effect of Cycle Length on Electrogram Morphology in Normal Subjects

  During ablation procedure

• Evaluate the Effect of Cycle Length on Electrogram Amplitude in Normal Subjects

  During ablation procedure

• Evaluate the Effect of Cycle Length on Electrogram Duration in Normal Subjects

  During ablation procedure

Study Arms (3)

Normal subject control group

EXPERIMENTAL

High density mapping of left atrial voltages in patients with supraventricular tachycardia

Diagnostic Test: High density electrophysiological mapping

Atrial fibrillation group

EXPERIMENTAL

High density mapping of left atrial voltages

Diagnostic Test: High density electrophysiological mapping

AcQMap atrial fibrillation group

EXPERIMENTAL

High density mapping of left atrial voltages and AcQMap propagation patterns alongside cardiac MRI

Diagnostic Test: High density electrophysiological mapping; Diagnostic Test: Cardiac Magnetic Resonance Imaging

Interventions

High density electrophysiological mapping DIAGNOSTIC_TEST

Recording of electrophysiological data using a high density contact catheter during pacing at the time of catheter ablation for atrial fibrillation.

AcQMap atrial fibrillation group; Atrial fibrillation group; Normal subject control group

Cardiac Magnetic Resonance Imaging DIAGNOSTIC_TEST

Late gadolinium enhance cardiac magnetic resonance imaging (in AcQMap group only)

AcQMap atrial fibrillation group

Eligibility Criteria

• Age: 18 Years+
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Participant is willing and able to give informed consent for participation in the study.
• Male or Female, aged 18 years or above.
• Diagnosed with paroxysmal or persistent atrial fibrillation and planned for a catheter ablation procedure (AF ablation group only).
• Undergoing elective left sided catheter ablation procedure involving a trans-septal approach (Control group only).
• In the Investigator's opinion the participant is able and willing to comply with all trial requirements.

You may not qualify if:

• Previous cardiac surgery.
• Previous left atrial ablation (catheter or surgical).
• Medical history including any of: atrial fibrillation, atrial flutter, hypertension, diabetes mellitus, chronic obstructive pulmonary disease, significant mitral valve disease (stenosis or regurgitation), pulmonary hypertension, obstructive sleep apnoea, ischaemic heart disease, cerebrovascular disease, peripheral vascular disease, structural heart disease (excluding known accessory pathway), congenital cardiac anomaly (excluding accessory pathway), previous left atrial ablation (catheter or surgical), cardiac surgery (control group only).
• Contraindications to MR scanning (such as metallic or electronic objects implanted in your body or history of severe claustrophobia) (AcQMap guided ablation group).
• Significantly impaired renal function (eGFR\<30ml/min).
• Female participant who is pregnant, lactating or planning pregnancy during the course of the trial.
• Any other significant disease or disorder which, in the opinion of the Investigator, may either put the participants at risk because of participation in the trial, or may influence the result of the trial, or the participant's ability to participate in the trial.
• Participants who have participated in another research trial involving an investigational medicinal product in the past 12 weeks. (Involvement in any other research trial is not a contraindication per se).

Sponsors & Collaborators

• Oxford University Hospitals NHS Trust: lead

Study Sites (1)

John Radcliffe Hospital

Oxford, Oxfordshire, OX3 9DU, United Kingdom

Location

MeSH Terms

Conditions

Atrial Fibrillation

Condition Hierarchy (Ancestors)

Arrhythmias, Cardiac; Heart Diseases; Cardiovascular Diseases; Pathologic Processes; Pathological Conditions, Signs and Symptoms

Results Point of Contact

• Title: Timothy R Betts
• Organization: Oxford University Hospitals NHS Foundation Trust

timothy.betts@cardiov.ox.ac.uk

+44 (0)1865 220256

Study Officials

• Timothy R Betts, MD MBChB FRCP

  Oxford University Hospitals NHS Trust

  PRINCIPAL INVESTIGATOR

Publication Agreements

• PI is Sponsor Employee: Yes

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: NON RANDOMIZED
• Masking: NONE
• Purpose: BASIC SCIENCE
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Primary Investigator

Study Record Dates

• First Submitted: January 7, 2020
• First Posted: January 18, 2020
• Study Start: December 7, 2020
• Primary Completion: November 2, 2023
• Study Completion: November 2, 2023
• Last Updated: August 19, 2025
• Results First Posted: August 19, 2025

Record last verified: 2025-07

Data Sharing

• IPD Sharing: Will not share

Locations

GB (1)