Atrial Fibrillation (AF)STRATA-AFNCT07047235
Substrate Remodelling and Targeted Ablation in AF
A study testing Pulmonary vein reisolation, Ganglionic plexi ablation and Substrate ablation in people with Atrial Fibrillation (AF) and Atrial Fibrillation Mechanisms, run by Barts & The London NHS Trust at 1 site in United Kingdom.
Trial summary
Atrial fibrillation (AF) is the most common heart rhythm disorder, affecting millions worldwide and causing symptoms such as palpitations, fatigue and breathlessness. It also increases the risk of stroke and heart failure, so effective treatment is essential. Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Atrial Fibrillation (AF), Atrial Fibrillation Mechanisms, Catheter Ablation
- What is being tested?
- Pulmonary vein reisolation, Ganglionic plexi ablation and Substrate ablation
- Type of treatment
- Surgery or procedure
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 160 participants
- Where
- 1 siteUnited Kingdom
- Study dates
- 7 Nov 2025to 18 Aug 2030
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Able and willing to provide written informed consent
- Age: 18 years or older
- Clinical diagnosis: Persistent atrial fibrillation
- Treatment status: Scheduled to undergo first-time catheter ablation for persistent AF
Who cannot join
- Inability or unwillingness to provide informed consent
- Under 18 years of age
- Previous left atrial ablation for AF or other atrial arrhythmias
- Any clinical contraindications to undergoing AF catheter ablation
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Sayed Al-Aidarous, MBBS, MRCP contact
United Kingdom1 site, 1 recruiting
- Recruiting
St Bartholomew's Hospital
London
About this study
Official title: Understanding Substrate Evolution in Persistent Atrial Fibrillation to Develop Tailored Ablation Strategies
Atrial fibrillation (AF) is the most common heart rhythm disorder, affecting millions worldwide and causing symptoms such as palpitations, fatigue and breathlessness. It also increases the risk of stroke and heart failure, so effective treatment is essential.
A treatment for AF involves catheter ablation, a minimally invasive procedure where problematic areas of the heart are targeted using controlled energy. This is done by passing wires called catheters, through blood vessels at the top of the leg all the way to the heart. However, this isn't effective for everyone and approximately half of patients experience a return of AF despite treatment.
Read more
In this researcher-led study at St Bartholomew's Hospital , the investigators will use a method called electroanatomical mapping to make a 3D picture of the left atrium, the heart's upper left chamber. To make this picture more detailed, information will be collected - such as how strong electrical signals are (voltage), how fast and in which direction they travel through the heart to describe abnormal areas and areas of scar within the heart. Information will also be gathered about the routes electricity takes and the nerve activity in the heart muscle. These detailed maps will help to understand why AF can continue indefinitely in some people, why ablation works for some people and not others, and improve how ablations are done to make them more effective.
All participants will undergo catheter ablation with these mapping methods integrated into the procedure. If AF recurs, patients will be invited for a second ablation targeting specific abnormal areas depending on the amount of scar found. This will be standardised across patients.
Patients will be followed for 12 months, with structured visits at 3, 6, 9 and 12 months and 48-hour ECG recorders at 6 and 12 months. By tracking how the heart's structure and electrical behaviour evolve, the aim is to to see if map-guided ablation reduces the need for further procedures, lowers healthcare costs and improves quality of life.
Ultimately, this study will provide clear, reproducible insights into AF mechanisms and yield practical guidance so clinicians can predict who will benefit from standard ablation treatment and who may require extra, map-guided treatment.
- Conditions
- Atrial Fibrillation (AF), Atrial Fibrillation Mechanisms, Catheter Ablation, Low Voltage Areas
- Being tested
- Pulmonary vein reisolation, Ganglionic plexi ablation, Substrate ablation
- Keywords
- ganglionic plexi, autonomic remodelling, substrate remodelling, conduction velocity
- Medical subject headings
- Atrial Fibrillation
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Pulmonary vein reisolationProcedure or surgery
The pulmonary veins will be checked electrically and further ablation will be undertaken if they are not isolated.
Ganglionic plexi ablationProcedure or surgery
Sites where ganglionix plexi have been found will be ablated.
Substrate ablationProcedure or surgery
Areas of rate dependent conduction velocity slowing will be targeted using cathether ablation
| Study group | Role | What they receive |
|---|---|---|
| Minimal Low Voltage Zones Group | Active comparator | These are patients who've had recurrence of AF after their first ablation and less than 30% of their atria is comprised of low voltage zones. They will undergo autonomic ganglionic plexi site ablation combined with pulmonary vein re-isolation. Receives: Procedure: Pulmonary vein reisolation; Procedure: Ganglionic plexi ablation |
| Significant Low Voltage Zones Group | Active comparator | These are patients who've had recurrence of AF after their first ablation and greater than 30% of their atria is comprised of low voltage zones. They will undergo targeted ablation of conduction slowing sites in addition to ganlionic plexi site ablation and pulmonary vein reisolation. Receives: Procedure: Pulmonary vein reisolation; Procedure: Ganglionic plexi ablation; Procedure: Substrate ablation |
What is being measured
The primary outcome is the main question the study is designed to answer.
Assessment of Electrical, Structural and Autonomic Remodelling in Persistent Atrial Fibrillation
A primary objective of this study is to delineate the remodelling changes that occur in persistent atrial fibrillation and to utilise these to develop tailored ablation strategies.
Measured: 4 years
Establish a Predictive Model to Idenitfy Which Patients are Responders to Pulmonary Vein Isolation Alone and Who Will Require Further Tailored Ablation Strategies
Based on clinical data approximately only 50% of patients with persistent atrial fibrillation who undergo pulmonary vein isolation remain in sinus rhythm. A main aim of the study is to develop a method to identify which patients will respond to pulmonary vein isolation alone and who will require further tailored ablation strategies.
Measured: 24 months
To Assess if Ablation of Rate Dependent Conduction Velocity Slowing Sites Improves Freedom from Atrial Fibrillation
All patients who recur after their initial ablation will be invited to undergo a repeat ablation procedure. All patients will undergo ganglionic plexi ablation and reisolation their pulmonary veins. Those who have low voltage zones of more than 30% of their total left atrium will undergo further ablation of rate dependent conduction velocity slowing sites.
Measured: 5 years
Secondary outcomes (1)
Develop Personalised Electrical Atrial Models
The data taken from the electrophysiological procedures will be used to create mathematical computer models that can be used as an environment to test electrophysiological theories and response to ablation.
Measured: 5 years
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted2 Jul 2025
- Study start7 Nov 2025
- Primary completion18 Nov 2029 (estimated)
- Study completion18 Aug 2030 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Atrial Fibrillation (AF)Studies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Other
- Allocation
- Non-randomised
- Intervention model
- Parallel groups
- Model description
- This study is a single-centre, prospective mechanistic cohort investigation with a nested interventional controlled study designed to comprehensively evaluate electrophysiological substrate remodelling and its relationship with procedural outcomes in patients undergoing catheter ablation for persistent AF. Patients already undergoing a first ablation for persistent atrial fibrillation will undergo extensive structural, electrical and autonomic modelling during their index ablation procedure. They will then be followed up for 1 year. Those whose AF recurs will be invited for a repeat procedure in which all patients will undergo reisolation of the pulmonary veins and ganglionic plexi. Those whose atria is comprised of low voltage zones more than 30 will additionally undergo susbtrate modification of rate dependent conduction velocity slowing sites. All these patients will then undergo further follow up for 12 months will be compared to propensity matched controls.
- Masking
- None (open label)
- Enrolment
- 160 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Barts & The London NHS Trust
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07047235
- Sponsor's protocol ID
- 407
- Acronym
- STRATA-AF
- Status last verified
- Nov 2025
- First submitted
- 24 Jun 2025
- Last updated
- 18 Nov 2025
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 18 Nov 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Understanding Substrate Evolution in Persistent Atrial Fibrillation to Develop Tailored Ablation Strategies
- ClinicalTrials.gov ID
- NCT07047235
- Acronym / sponsor ID
- STRATA-AF / 407
- Conditions
- Atrial Fibrillation (AF), Atrial Fibrillation Mechanisms, Catheter Ablation, Low Voltage Areas
- Keywords
- ganglionic plexi, autonomic remodelling, substrate remodelling, conduction velocity
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 160 participants (estimated)
- Lead sponsor
- Barts & The London NHS TrustUniversity, hospital or other
- Study start
- 7 Nov 2025 (actual)
- Primary completion
- 18 Nov 2029 (estimated)
- Study completion
- 18 Aug 2030 (estimated)
- First posted
- 2 Jul 2025 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Atrial fibrillation (AF) is the most common heart rhythm disorder, affecting millions worldwide and causing symptoms such as palpitations, fatigue and breathlessness. It also increases the risk of stroke and heart failure, so effective treatment is essential.
A treatment for AF involves catheter ablation, a minimally invasive procedure where problematic areas of the heart are targeted using controlled energy. This is done by passing wires called catheters, through blood vessels at the top of the leg all the way to the heart. However, this isn't effective for everyone and approximately half of patients experience a return of AF despite treatment.
In this researcher-led study at St Bartholomew's Hospital , the investigators will use a method called electroanatomical mapping to make a 3D picture of the left atrium, the heart's upper left chamber. To make this picture more detailed, information will be collected - such as how strong electrical signals are (voltage), how fast and in which direction they travel through the heart to describe abnormal areas and areas of scar within the heart. Information will also be gathered about the routes electricity takes and the nerve activity in the heart muscle. These detailed maps will help to understand why AF can continue indefinitely in some people, why ablation works for some people and not others, and improve how ablations are done to make them more effective.
All participants will undergo catheter ablation with these mapping methods integrated into the procedure. If AF recurs, patients will be invited for a second ablation targeting specific abnormal areas depending on the amount of scar found. This will be standardised across patients.
Patients will be followed for 12 months, with structured visits at 3, 6, 9 and 12 months and 48-hour ECG recorders at 6 and 12 months. By tracking how the heart's structure and electrical behaviour evolve, the aim is to to see if map-guided ablation reduces the need for further procedures, lowers healthcare costs and improves quality of life.
Ultimately, this study will provide clear, reproducible insights into AF mechanisms and yield practical guidance so clinicians can predict who will benefit from standard ablation treatment and who may require extra, map-guided treatment.
Study design
- Primary purpose
- Other
- Allocation
- Non-randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Number of arms
- 2
- Model description
- This study is a single-centre, prospective mechanistic cohort investigation with a nested interventional controlled study designed to comprehensively evaluate electrophysiological substrate remodelling and its relationship with procedural outcomes in patients undergoing catheter ablation for persistent AF. Patients already undergoing a first ablation for persistent atrial fibrillation will undergo extensive structural, electrical and autonomic modelling during their index ablation procedure. They will then be followed up for 1 year. Those whose AF recurs will be invited for a repeat procedure in which all patients will undergo reisolation of the pulmonary veins and ganglionic plexi. Those whose atria is comprised of low voltage zones more than 30 will additionally undergo susbtrate modification of rate dependent conduction velocity slowing sites. All these patients will then undergo further follow up for 12 months will be compared to propensity matched controls.
| Arm | Type | Receives |
|---|---|---|
| Minimal Low Voltage Zones Group | Active comparator | Procedure: Pulmonary vein reisolation, Procedure: Ganglionic plexi ablationThese are patients who've had recurrence of AF after their first ablation and less than 30% of their atria is comprised of low voltage zones. They will undergo autonomic ganglionic plexi site ablation combined with pulmonary vein re-isolation. |
| Significant Low Voltage Zones Group | Active comparator | Procedure: Pulmonary vein reisolation, Procedure: Ganglionic plexi ablation, Procedure: Substrate ablationThese are patients who've had recurrence of AF after their first ablation and greater than 30% of their atria is comprised of low voltage zones. They will undergo targeted ablation of conduction slowing sites in addition to ganlionic plexi site ablation and pulmonary vein reisolation. |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (4 listed)
- Able and willing to provide written informed consent
- Age: 18 years or older
- Clinical diagnosis: Persistent atrial fibrillation
- Treatment status: Scheduled to undergo first-time catheter ablation for persistent AF
Key exclusion criteria (4 listed)
- Inability or unwillingness to provide informed consent
- Under 18 years of age
- Previous left atrial ablation for AF or other atrial arrhythmias
- Any clinical contraindications to undergoing AF catheter ablation
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Pulmonary vein reisolationThe pulmonary veins will be checked electrically and further ablation will be undertaken if they are not isolated. | Procedure or surgery | Minimal Low Voltage Zones Group, Significant Low Voltage Zones Group |
| Ganglionic plexi ablationSites where ganglionix plexi have been found will be ablated. | Procedure or surgery | Minimal Low Voltage Zones Group, Significant Low Voltage Zones Group |
| Substrate ablationAreas of rate dependent conduction velocity slowing will be targeted using cathether ablation | Procedure or surgery | Significant Low Voltage Zones Group |
Primary outcome
Assessment of Electrical, Structural and Autonomic Remodelling in Persistent Atrial Fibrillation
Time frame: 4 years
A primary objective of this study is to delineate the remodelling changes that occur in persistent atrial fibrillation and to utilise these to develop tailored ablation strategies.
Establish a Predictive Model to Idenitfy Which Patients are Responders to Pulmonary Vein Isolation Alone and Who Will Require Further Tailored Ablation Strategies
Time frame: 24 months
Based on clinical data approximately only 50% of patients with persistent atrial fibrillation who undergo pulmonary vein isolation remain in sinus rhythm. A main aim of the study is to develop a method to identify which patients will respond to pulmonary vein isolation alone and who will require further tailored ablation strategies.
To Assess if Ablation of Rate Dependent Conduction Velocity Slowing Sites Improves Freedom from Atrial Fibrillation
Time frame: 5 years
All patients who recur after their initial ablation will be invited to undergo a repeat ablation procedure. All patients will undergo ganglionic plexi ablation and reisolation their pulmonary veins. Those who have low voltage zones of more than 30% of their total left atrium will undergo further ablation of rate dependent conduction velocity slowing sites.
1 secondary outcome
Develop Personalised Electrical Atrial Models
Time frame: 5 years
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 18 Nov 2025.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Sayed Al-Aidarous, MBBS, MRCP contact
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Pulmonary vein reisolation, Ganglionic plexi ablation and Substrate ablation in people with Atrial Fibrillation (AF) and Atrial Fibrillation Mechanisms, run by Barts & The London NHS Trust at 1 site in United Kingdom.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 4 inclusion and 4 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 18 Nov 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United Kingdom. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Shohreh Honarbakhsh, MBBS, MRCP, PhD (02037658682, shohreh.honarbakhsh@nhs.net), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Assessment of Electrical, Structural and Autonomic Remodelling in Persistent Atrial Fibrillation (time frame: 4 years). The study lists 3 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 18 Nov 2025.