Atrial FibrillationHD-SAGANCT03363087
High Density Scar Guided Atrial Fibrillation Mapping
A study testing Mapping and ablation and Mapping in people with Atrial Fibrillation, run by University Hospital Southampton NHS Foundation Trust at 1 site in United Kingdom.
Trial summary
HD SAGA: There is increasing evidence that having AF is associated with some scarring of the upper chamber of the heart, the left atrium. There is also evidence that the amount of scarring can predict ablation success rates. Read more about this study
- Who is it for?
- Ages 18 to 90 years
- Conditions the study is for
- Atrial Fibrillation
- What is being tested?
- Mapping and ablation and Mapping
- Type of treatment
- Medical device
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 60 participants
- Where
- 1 siteUnited Kingdom
- Study dates
- 27 Aug 2019to 1 Mar 2023
- Phase
- Interventional
- Are there results?
- None posted in the registry
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 to 90 years
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- trial Fibrillation, Scheduled for ablation on clinical grounds Able/willing to consent to procedure/research protocol No contraindication to clinical ablation
Who cannot join
- Unable/unwilling to consent Contraindication to clinical ablation
Trial locations and contacts
1 site in 1 country.
United Kingdom1 site
University Hospital Southampton
Southampton, Hampshire, SO16 6YD
About this study
Official title: High Density Scar Guided Atrial Fibrillation Mapping (HD SAGA) / High Density Scar Guided Atrial Fibrillation Mapping StablePoint (HD SAGA S)/ High Density Scar Guided Atrial Fibrillation Mapping HD Grid (HD SAGA H)
HD SAGA:
There is increasing evidence that having AF is associated with some scarring of the upper chamber of the heart, the left atrium. There is also evidence that the amount of scarring can predict ablation success rates. Recently, rapid ultra high density mapping equipment has become available and this has the capability of defining the electrical scar in the atrium in detail. The equipment used to do this is standard approved equipment for the procedure but its use for making scar maps has not been fully assessed.
Read more
In the mapping phase of the study therefore, the aim will be to collect high density scar maps in AF and normal rhythm to see how they compare. Maps will be collected in different ways to see if that changes their accuracy. The study will also assess if the values previously suggested as representing scar with lower density mapping systems are still appropriate where high density mapping equipment is used. The results from this study will help to improve the understanding of scar in the atrium and help demonstrate the most efficient way to collect scar information using this high density mapping equipment. In the future, clinicians may be able to use these very detailed scar maps to tailor and refine the way they ablate patients with AF, though the focus of the current study is just on collecting the scar information.
While identifying areas requiring ablation is important to an ablation procedure, the other important aspect is the efficacy of ablation. Until now, we have been reliant on assessing our inputs into an ablation (such as the level of contact and the power delivered) but have been limited in the assessment of the output of an ablation in terms of lesion characteristics. New ablation catheter technology is now available which can assess the localised impedance drop with ablation. This is likely a better surrogate for lesion parameters than what we have previously had available and merits further study. Based on such study, we may be able to define targets for ablation which would help to guide future ablations.
HD SAGA S:
Approval amendment March 2021 In addition to the above, using new catheter technology incorporating contact force into the assessment of ablation lesion efficacy.
HD SAGA H:
Approval amendment March 2021 Using new mapping catheter (HD Grid) and algorithms (HD Wave) to compare scar maps between AF and SR and pre-establish pulmonary vein isolation lines.
Read the detailed description
HD SAGA:
The study would propose to use the Rhythmia Ultra High Density (UHD) mapping system (Boston Scientific) firstly to generate scar maps to determine if the results are comparable with previous work using lower density systems. Scar maps would be acquired in 3 groups of patients. The first group would be Redo-persistent AF ablation cases as these patients would have expected LA scar (iatrogenic and non-iatrogenic) from their previous ablation procedure. De novo persistent AF patients who would be expected to have non-iatrogenic scar. De novo paroxysmal AF patients who would be expected to have no or minimal scar. In redo AF patients, the validity of the scar maps would be further explored by undertaking re-isolation of veins based on discontinuities in the pulmonary vein isolation lines. If this is proven to be effective, it would demonstrate that the scar picked up by the system is genuine and may also suggest a more effective use of UHD systems for redo-pulmonary vein isolation (PVI).
In the ablation phase, we would be assessing the effect of ablation on the localised ablation characteristics of the tissue to assess how this is affected by ablation. From previous work, using conventional, wide area impedance measurements, there is a notable plateau in the impedance drop with ablation suggesting a point beyond which there is minimal efficacy gain from further ablation. One would expect this would be even more apparent with localised impedance.
Original Hypothesis - mapping phase An UHD mapping system can be utilised to generate automated, rapid, high density atrial scar maps in AF to guide a scar-based ablation strategy.
Original Hypothesis - ablation phase Localised Impedance will fall during ablation and this fall will plateau, suggesting a biophysical target for ablation
There is a small body of literature addressing contact mapping of atrial scar but this has mainly relied on lower density mapping approaches. UHD mapping systems offer the advantage of true high-density mapping with improved signal to noise ratios that one would predict will lead to the generation of more accurate maps. These advantages are also such that one would predict scar maps in AF would be more accurate. Extending the scar maps to incorporate the RA is also novel in this context and would give an insight into the degree to which AF is a bi-atrial fibrotic cardiomyopathy. As the use of UHD mapping is novel, it is important to establish how relevant criteria used in lower density, lower fidelity mapping systems are when the newer system is used, especially in defining scar.
No clinical studies have been published assessing localised impedance.
Protocol Fifteen patients listed for persistent AF ablation would be recruited including redo-ablation patients (aiming for 5 de novo and 10 redo patients). All these patients would be in AF at the time of the procedure. A further 5 patients with paroxysmal AF would also be recruited. Procedures would be performed on uninterrupted anticoagulation with a pre-procedural TOE as dictated by local guidelines. Moderate sedation or general anaesthetic procedures would be included. Intravenous heparin would be used to maintain the ACT at a therapeutic level throughout the study. All mapping would be undertaken using the Orion high density multipolar mapping catheter with the Rhythmia system. The ablation catheter used would be the IntellaNav MiFi Open Irrigated Temperature Ablation Catheter.
An RA scar map would be obtained using WCT as a reference. Double transseptal access would be obtained and the mapping and ablation catheters passed into the LA.
An LA scar map would be taken with the mapping catheter. For paroxysmal AF cases in sinus rhythm, this would be the only LA map taken. For patients in AF, maps would be taken in AF and then in sinus rhythm. In redo cases, the veins which the scar map suggests are likely to be reconnected would be noted (based on discontinuities in the wide area circumferential ablation (WACA) lines). The mapping catheter would then be used to confirm the presence of electrical reconnection of each vein. The patient would then be cardioverted if in AF and the mapping process repeated using a WCT reference. With all maps, the aim would be complete LA coverage. For the sinus rhythm maps, the LA will be divided into 5 sites: roof, posterior wall, inferior wall, septum, anterior wall bordering left atrial appendage. Within each of these sites, the pacing threshold will be assessed at 3 locations incorporating a spread of bipolar voltages.
Following the mapping phase, the case would then proceed as per the operator's standard methodology. The aim would be to collect at least 30 static study ablation points as discussed above. Vein re-isolation would be performed without any catheter measuring electrical activity in the vein, purely based on the scar map, targeting discontinuities in the WACA lines. Ablations would be static rather than drag ablations and at each point, the electrogram from the MiFi electrodes would be recorded at the start and end of ablation. Pacing would be performed during ablation and the impedance value at which pacing capture was lost would be noted. Following this ablation, the mapping catheter would be utilised to establish if the vein has been electrically disconnected based on the scar map.
At the end of the case, in sinus rhythm, scar maps of the RA would be taken. In sinus rhythm, pacing would be undertaken as for the LA at the following sites: anterior wall, posterior wall, septum and lateral wall.
The scar maps would be exported offline to allow quantitative analysis, as would the electrogram and impedance data. The analysis would be performed using the Matlab programming environment.
The scar analysis will exclude any portions of the LA distal to the WACA lines. The initial step will be to give a low voltage zone percentage. The next step will be to identify congruent low voltage zones and give advice regarding the ablation strategy for these - whether this involved delivering lines, for instance for a large posterior wall scar, and if the ablation needs to be extended to other inexcitable structures to prevent leaving a narrow conducting isthmus.
Study Follow up There would be no additional follow up for this study - the participants' follow up will follow the normal clinical practice at University Hospital Southampton.
HD SAGA S:
Protocol:
Twenty patients will be recruited for the HD-SAGAS cohort, all with persistent AF who will be in AF at the time of the procedure. These can be de novo or redo procedure patients.
Procedures would be performed on uninterrupted anticoagulation with a pre-procedural imaging as dictated by local guidelines. Moderate sedation or general anaesthetic procedures would be included. Intravenous heparin would be used to maintain the ACT at a therapeutic level throughout the study. All mapping would be undertaken using the Orion high density multipolar mapping catheter with the Rhythmia system. The ablation catheter used would be the Stablepoint catheter.
An LA scar map would be taken with the mapping catheter. The first map would be collected in AF. Following this, at 5 locations in the LA, aiming for a spread of voltages and locations, the contact force would be increased from 0-40g and the LI noted. The patient would then be cardioverted and a map taken in sinus rhythm with right atrial pacing. With all maps, the aim would be complete LA coverage. After cardioversion, at the same spots assessed in AF, the contact force would again be increased from 0-40g and the LI noted once more. Pacing thresholds would also be checked at these locations with a stable contact force of 10-20g to ensure good contact. The pacing phase could be after the ablation phase depending on rhythm stability.
Following the mapping phase, the case would then proceed as per the operator's standard methodology. The operator will be allowed to use whichever powers they wish to during ablation. Sites of acute reconnection would be noted.
At the end of the case, in sinus rhythm, pacing thresholds would be assessed in 5 areas in the LA, aiming for a spread of areas and voltages.
HD SAGA H:
The study would use the HD Grid catheter and Precision mapping system from Abbott. The HD Grid catheter has a unique arrangement of electrodes that allows for 3D electroanatomical maps to be generated between bipoles of different orientations. Following this a novel algorithm (HD Wave) provides the the point with largest amplitude. This abrogates the directional limitations of conventional bipolar mapping. Thus smaller more accurate areas of scar could be seen with the left atrium as has been generated in previous studies in the left ventricle.
Hypothesis The use of HD Wave mapping and the best duplicate algorithm will lead to more reliable voltage maps in AF - both throughout the LA body and in the PVI lines. The gold standard to compare with here will be the sinus rhythm maps.
Primary comparison:
Sinus rhythm HD wave versus AF HD wave map Scar volume PVI gaps
Secondary comparisons:
Scar volumes and PVI gaps Sinus rhythm HD wave versus conventional AF HD wave versus conventional
Protocol 20 patients listed for redo ablation of persistent AF, in AF at the time of procedure. All procedures would be performed using the precision mapping system.
The operator would collect a voltage map of the left atrium using the HD Grid catheter in AF. Following this, the patient would be cardioverted and another map collected with the same mapping catheter during CS proximal pacing.
The procedure would then proceed as per usual care. Subsequent to the procedure, the mapping functions would be applied to the data by Turbo mapping.
Sites of PV reconnection would be noted based on the ablations performed by the operator.
- Conditions
- Atrial Fibrillation
- Being tested
- Mapping and ablation, Mapping
- Keywords
- Atrial Scar, Atrial Fibrillation Ablation, Mapping, Persistent Atrial Fibrillation, Catheter Ablation
- Medical subject headings
- Atrial Fibrillation
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Mapping and ablationDevice
Ultra high density scar mapping Collection of impedance data during ablation
MappingDevice
Omnipolar mapping of left atrial scar and pulmonary vein isolation lines
| Study group | Role | What they receive |
|---|---|---|
| Mapping (Rhythmia) and ablation (IntellaNav MiFi) | Experimental | Automated high density biatrial scar mapping Pacing confirmation of scar Collection of impedance data during clinical ablation Receives: Device: Mapping and ablation |
| Mapping (Rhythmia) and ablation (StablePoint) | Experimental | Automated high density biatrial scar mapping Pacing confirmation of scar Collection of impedance data during clinical ablation Contact force measurements Receives: Device: Mapping and ablation |
| Mapping (Precision) | Experimental | Automated high density left atrial mapping in AF and SR in different bipole orientations Receives: Device: Mapping |
What is being measured
The primary outcome is the main question the study is designed to answer.
Scar Volume
Quantification of scar volumes - presented as a proportion of the total atrial geometry volume
Measured: Through study completion, an average of 1 year
Impedance values with ablation
Collection of localised and conventional impedance during ablation
Measured: Through study completion, an average of 1 year
Scar volume and pulmonary vein isolation line gaps
Scar volume and pulmonary vein isolation line gaps between AF and SR
Measured: Through study completion, an average of 1 year
Secondary outcomes (14)
Confirm Scar Thresholds
Pacing threshold in mV will be assessed at different levels of atrial scar
Measured: Through study completion, an average of 1 year
Compare scar volumes in AF and sinus rhythm in the same patient
Quantitative comparison - comparing the scar areas in cm2 between the two maps
Measured: Through study completion, an average of 1 year
Compare maps generated using internal unipolar reference and Wilson's Central Terminus
Quantitative comparison - comparing the scar areas in cm2 between the two maps
Measured: Through study completion, an average of 1 year
Localised impedance fall during ablation
Compare the LI fall versus time relationship to assess the nature of the relationship with the aim of generating a target for LI fall with ablation
Measured: Through study completion, an average of 1 year
Localised impedance fall versus electrogram attenuation
Compare the LI impedance fall with ablation with electrogram attenuation (on microelectrodes) to further provide evidence for an LI target
Measured: Through study completion, an average of 1 year
Localised impedance fall versus pacing capture
Compare the LI impedance fall with ablation with loss of acing capture during ablation to further provide evidence for an LI target
Measured: Through study completion, an average of 1 year
Compare localised with conventional impedance values during ablation
Compare localised with conventional impedance values during ablation
Measured: Through study completion, an average of 1 year
Compare contact force measurements to local impedance
Compare contact force (grams) measurements to local impedance (ohms) during ablation to establish if increasing levels of contact force result in greater local impedance drops
Measured: Through study completion, an average of 1 year
Compare left atrial scar area between omnipolar and bipolar mapping in atrial fibrillation
Quantative comparison in cm2 of the level of atrial scar between 2 types of map in atrial fibrillation
Measured: Through study completion, an average of 1 year
Compare left atrial scar area between omnipolar and bipolar mapping in sinus rhythm
Quantative comparison in cm2 of the level of atrial scar between 2 types of map in sinus rhythm
Measured: Through study completion, an average of 1 year
Compare left atrial scar area in omnipolar maps between sinus rhythm and atrial fibrillation
Quantative comparison in cm2 of omnipolar maps between two heart rhythms
Measured: Through study completion, an average of 1 year
Compare left atrial scar areas in bipolar maps between sinus rhythm and atrial fibrillation
Quantative comparison in cm2 of bipolar maps between two heart rhythms
Measured: Through study completion, an average of 1 year
Compare identification of pulmonary vein isolation gaps between omnipolar and bipolar maps
Identifiying the presence of gaps within previously created pulmonary vein isolation lines between omnipolar and bipolar mapping
Measured: Through study completion, an average of 1 year
Compare identification of pulmonary vein isolation gaps between sinus rhythm and atrial fibrillation
Identifiying the presence of gaps within previously created pulmonary vein isolation lines between different heart rhythms within the same patient
Measured: Through study completion, an average of 1 year
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted6 Dec 2017
- Study start27 Aug 2019
- Primary completion1 Mar 2023
- Study completion1 Mar 2023
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Atrial FibrillationStudies 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
- Diagnosis
- Allocation
- Non-randomised
- Intervention model
- Single group
- Model description
- Biatrial automated scar mapping in patients undergoing ablation for atrial fibrillation. Confirmation of scar by pacing in all patients. Collection of impedance data during clinical ablation.
- Masking
- None (open label)
- Enrolment
- 60 participants (actual)
Sponsor and investigators
- Lead sponsor
- University Hospital Southampton NHS Foundation Trust
- Sponsor type
- University, hospital or other
- Collaborators
- Boston Scientific Corporation, Abbott
- Responsible party
- Sponsor
- Investigators
- Waqas Ullah, PhD, Principal investigator, University Hospital Southampton NHS Foundation Trust
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT03363087
- Sponsor's protocol ID
- RHM CAR0523
- Acronym
- HD-SAGA
- Status last verified
- Jun 2022
- First submitted
- 28 Jul 2017
- Last updated
- 18 May 2025
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No: No plans to share IPD
Study at a glance
From the registry record, last updated by the sponsor on 18 May 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- High Density Scar Guided Atrial Fibrillation Mapping (HD SAGA) / High Density Scar Guided Atrial Fibrillation Mapping StablePoint (HD SAGA S)/ High Density Scar Guided Atrial Fibrillation Mapping HD Grid (HD SAGA H)
- ClinicalTrials.gov ID
- NCT03363087
- Acronym / sponsor ID
- HD-SAGA / RHM CAR0523
- Conditions
- Atrial Fibrillation
- Keywords
- Atrial Scar, Atrial Fibrillation Ablation, Mapping, Persistent Atrial Fibrillation, Catheter Ablation
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 60 participants (actual)
- Lead sponsor
- University Hospital Southampton NHS Foundation TrustUniversity, hospital or other
- Collaborators
- Boston Scientific Corporation, Abbott
- Study start
- 27 Aug 2019 (actual)
- Primary completion
- 1 Mar 2023 (actual)
- Study completion
- 1 Mar 2023 (actual)
- First posted
- 6 Dec 2017 (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.
HD SAGA:
There is increasing evidence that having AF is associated with some scarring of the upper chamber of the heart, the left atrium. There is also evidence that the amount of scarring can predict ablation success rates. Recently, rapid ultra high density mapping equipment has become available and this has the capability of defining the electrical scar in the atrium in detail. The equipment used to do this is standard approved equipment for the procedure but its use for making scar maps has not been fully assessed.
In the mapping phase of the study therefore, the aim will be to collect high density scar maps in AF and normal rhythm to see how they compare. Maps will be collected in different ways to see if that changes their accuracy. The study will also assess if the values previously suggested as representing scar with lower density mapping systems are still appropriate where high density mapping equipment is used. The results from this study will help to improve the understanding of scar in the atrium and help demonstrate the most efficient way to collect scar information using this high density mapping equipment. In the future, clinicians may be able to use these very detailed scar maps to tailor and refine the way they ablate patients with AF, though the focus of the current study is just on collecting the scar information.
While identifying areas requiring ablation is important to an ablation procedure, the other important aspect is the efficacy of ablation. Until now, we have been reliant on assessing our inputs into an ablation (such as the level of contact and the power delivered) but have been limited in the assessment of the output of an ablation in terms of lesion characteristics. New ablation catheter technology is now available which can assess the localised impedance drop with ablation. This is likely a better surrogate for lesion parameters than what we have previously had available and merits further study. Based on such study, we may be able to define targets for ablation which would help to guide future ablations.
HD SAGA S:
Approval amendment March 2021 In addition to the above, using new catheter technology incorporating contact force into the assessment of ablation lesion efficacy.
HD SAGA H:
Approval amendment March 2021 Using new mapping catheter (HD Grid) and algorithms (HD Wave) to compare scar maps between AF and SR and pre-establish pulmonary vein isolation lines.
Detailed description
HD SAGA:
The study would propose to use the Rhythmia Ultra High Density (UHD) mapping system (Boston Scientific) firstly to generate scar maps to determine if the results are comparable with previous work using lower density systems. Scar maps would be acquired in 3 groups of patients. The first group would be Redo-persistent AF ablation cases as these patients would have expected LA scar (iatrogenic and non-iatrogenic) from their previous ablation procedure. De novo persistent AF patients who would be expected to have non-iatrogenic scar. De novo paroxysmal AF patients who would be expected to have no or minimal scar. In redo AF patients, the validity of the scar maps would be further explored by undertaking re-isolation of veins based on discontinuities in the pulmonary vein isolation lines. If this is proven to be effective, it would demonstrate that the scar picked up by the system is genuine and may also suggest a more effective use of UHD systems for redo-pulmonary vein isolation (PVI).
In the ablation phase, we would be assessing the effect of ablation on the localised ablation characteristics of the tissue to assess how this is affected by ablation. From previous work, using conventional, wide area impedance measurements, there is a notable plateau in the impedance drop with ablation suggesting a point beyond which there is minimal efficacy gain from further ablation. One would expect this would be even more apparent with localised impedance.
Original Hypothesis - mapping phase An UHD mapping system can be utilised to generate automated, rapid, high density atrial scar maps in AF to guide a scar-based ablation strategy.
Original Hypothesis - ablation phase Localised Impedance will fall during ablation and this fall will plateau, suggesting a biophysical target for ablation
There is a small body of literature addressing contact mapping of atrial scar but this has mainly relied on lower density mapping approaches. UHD mapping systems offer the advantage of true high-density mapping with improved signal to noise ratios that one would predict will lead to the generation of more accurate maps. These advantages are also such that one would predict scar maps in AF would be more accurate. Extending the scar maps to incorporate the RA is also novel in this context and would give an insight into the degree to which AF is a bi-atrial fibrotic cardiomyopathy. As the use of UHD mapping is novel, it is important to establish how relevant criteria used in lower density, lower fidelity mapping systems are when the newer system is used, especially in defining scar.
No clinical studies have been published assessing localised impedance.
Protocol Fifteen patients listed for persistent AF ablation would be recruited including redo-ablation patients (aiming for 5 de novo and 10 redo patients). All these patients would be in AF at the time of the procedure. A further 5 patients with paroxysmal AF would also be recruited. Procedures would be performed on uninterrupted anticoagulation with a pre-procedural TOE as dictated by local guidelines. Moderate sedation or general anaesthetic procedures would be included. Intravenous heparin would be used to maintain the ACT at a therapeutic level throughout the study. All mapping would be undertaken using the Orion high density multipolar mapping catheter with the Rhythmia system. The ablation catheter used would be the IntellaNav MiFi Open Irrigated Temperature Ablation Catheter.
An RA scar map would be obtained using WCT as a reference. Double transseptal access would be obtained and the mapping and ablation catheters passed into the LA.
An LA scar map would be taken with the mapping catheter. For paroxysmal AF cases in sinus rhythm, this would be the only LA map taken. For patients in AF, maps would be taken in AF and then in sinus rhythm. In redo cases, the veins which the scar map suggests are likely to be reconnected would be noted (based on discontinuities in the wide area circumferential ablation (WACA) lines). The mapping catheter would then be used to confirm the presence of electrical reconnection of each vein. The patient would then be cardioverted if in AF and the mapping process repeated using a WCT reference. With all maps, the aim would be complete LA coverage. For the sinus rhythm maps, the LA will be divided into 5 sites: roof, posterior wall, inferior wall, septum, anterior wall bordering left atrial appendage. Within each of these sites, the pacing threshold will be assessed at 3 locations incorporating a spread of bipolar voltages.
Following the mapping phase, the case would then proceed as per the operator's standard methodology. The aim would be to collect at least 30 static study ablation points as discussed above. Vein re-isolation would be performed without any catheter measuring electrical activity in the vein, purely based on the scar map, targeting discontinuities in the WACA lines. Ablations would be static rather than drag ablations and at each point, the electrogram from the MiFi electrodes would be recorded at the start and end of ablation. Pacing would be performed during ablation and the impedance value at which pacing capture was lost would be noted. Following this ablation, the mapping catheter would be utilised to establish if the vein has been electrically disconnected based on the scar map.
At the end of the case, in sinus rhythm, scar maps of the RA would be taken. In sinus rhythm, pacing would be undertaken as for the LA at the following sites: anterior wall, posterior wall, septum and lateral wall.
The scar maps would be exported offline to allow quantitative analysis, as would the electrogram and impedance data. The analysis would be performed using the Matlab programming environment.
The scar analysis will exclude any portions of the LA distal to the WACA lines. The initial step will be to give a low voltage zone percentage. The next step will be to identify congruent low voltage zones and give advice regarding the ablation strategy for these - whether this involved delivering lines, for instance for a large posterior wall scar, and if the ablation needs to be extended to other inexcitable structures to prevent leaving a narrow conducting isthmus.
Study Follow up There would be no additional follow up for this study - the participants' follow up will follow the normal clinical practice at University Hospital Southampton.
HD SAGA S:
Protocol:
Twenty patients will be recruited for the HD-SAGAS cohort, all with persistent AF who will be in AF at the time of the procedure. These can be de novo or redo procedure patients.
Procedures would be performed on uninterrupted anticoagulation with a pre-procedural imaging as dictated by local guidelines. Moderate sedation or general anaesthetic procedures would be included. Intravenous heparin would be used to maintain the ACT at a therapeutic level throughout the study. All mapping would be undertaken using the Orion high density multipolar mapping catheter with the Rhythmia system. The ablation catheter used would be the Stablepoint catheter.
An LA scar map would be taken with the mapping catheter. The first map would be collected in AF. Following this, at 5 locations in the LA, aiming for a spread of voltages and locations, the contact force would be increased from 0-40g and the LI noted. The patient would then be cardioverted and a map taken in sinus rhythm with right atrial pacing. With all maps, the aim would be complete LA coverage. After cardioversion, at the same spots assessed in AF, the contact force would again be increased from 0-40g and the LI noted once more. Pacing thresholds would also be checked at these locations with a stable contact force of 10-20g to ensure good contact. The pacing phase could be after the ablation phase depending on rhythm stability.
Following the mapping phase, the case would then proceed as per the operator's standard methodology. The operator will be allowed to use whichever powers they wish to during ablation. Sites of acute reconnection would be noted.
At the end of the case, in sinus rhythm, pacing thresholds would be assessed in 5 areas in the LA, aiming for a spread of areas and voltages.
HD SAGA H:
The study would use the HD Grid catheter and Precision mapping system from Abbott. The HD Grid catheter has a unique arrangement of electrodes that allows for 3D electroanatomical maps to be generated between bipoles of different orientations. Following this a novel algorithm (HD Wave) provides the the point with largest amplitude. This abrogates the directional limitations of conventional bipolar mapping. Thus smaller more accurate areas of scar could be seen with the left atrium as has been generated in previous studies in the left ventricle.
Hypothesis The use of HD Wave mapping and the best duplicate algorithm will lead to more reliable voltage maps in AF - both throughout the LA body and in the PVI lines. The gold standard to compare with here will be the sinus rhythm maps.
Primary comparison:
Sinus rhythm HD wave versus AF HD wave map Scar volume PVI gaps
Secondary comparisons:
Scar volumes and PVI gaps Sinus rhythm HD wave versus conventional AF HD wave versus conventional
Protocol 20 patients listed for redo ablation of persistent AF, in AF at the time of procedure. All procedures would be performed using the precision mapping system.
The operator would collect a voltage map of the left atrium using the HD Grid catheter in AF. Following this, the patient would be cardioverted and another map collected with the same mapping catheter during CS proximal pacing.
The procedure would then proceed as per usual care. Subsequent to the procedure, the mapping functions would be applied to the data by Turbo mapping.
Sites of PV reconnection would be noted based on the ablations performed by the operator.
Study design
- Primary purpose
- Diagnosis
- Allocation
- Non-randomised
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 3
- Model description
- Biatrial automated scar mapping in patients undergoing ablation for atrial fibrillation. Confirmation of scar by pacing in all patients. Collection of impedance data during clinical ablation.
| Arm | Type | Receives |
|---|---|---|
| Mapping (Rhythmia) and ablation (IntellaNav MiFi) | Experimental | Device: Mapping and ablationAutomated high density biatrial scar mapping Pacing confirmation of scar Collection of impedance data during clinical ablation |
| Mapping (Rhythmia) and ablation (StablePoint) | Experimental | Device: Mapping and ablationAutomated high density biatrial scar mapping Pacing confirmation of scar Collection of impedance data during clinical ablation Contact force measurements |
| Mapping (Precision) | Experimental | Device: MappingAutomated high density left atrial mapping in AF and SR in different bipole orientations |
Who may qualify
- Ages
- 18 to 90 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (1 listed)
- trial Fibrillation, Scheduled for ablation on clinical grounds Able/willing to consent to procedure/research protocol No contraindication to clinical ablation
Key exclusion criteria (1 listed)
- Unable/unwilling to consent Contraindication to clinical 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 |
|---|---|---|
| Mapping and ablationUltra high density scar mapping Collection of impedance data during ablation | Device | Mapping (Rhythmia) and ablation (IntellaNav MiFi), Mapping (Rhythmia) and ablation (StablePoint) |
| MappingOmnipolar mapping of left atrial scar and pulmonary vein isolation lines | Device | Mapping (Precision) |
Primary outcome
Scar Volume
Time frame: Through study completion, an average of 1 year
Quantification of scar volumes - presented as a proportion of the total atrial geometry volume
Impedance values with ablation
Time frame: Through study completion, an average of 1 year
Collection of localised and conventional impedance during ablation
Scar volume and pulmonary vein isolation line gaps
Time frame: Through study completion, an average of 1 year
Scar volume and pulmonary vein isolation line gaps between AF and SR
14 secondary outcomes
Confirm Scar Thresholds
Time frame: Through study completion, an average of 1 year
Compare scar volumes in AF and sinus rhythm in the same patient
Time frame: Through study completion, an average of 1 year
Compare maps generated using internal unipolar reference and Wilson's Central Terminus
Time frame: Through study completion, an average of 1 year
Localised impedance fall during ablation
Time frame: Through study completion, an average of 1 year
Localised impedance fall versus electrogram attenuation
Time frame: Through study completion, an average of 1 year
Localised impedance fall versus pacing capture
Time frame: Through study completion, an average of 1 year
Compare localised with conventional impedance values during ablation
Time frame: Through study completion, an average of 1 year
Compare contact force measurements to local impedance
Time frame: Through study completion, an average of 1 year
Compare left atrial scar area between omnipolar and bipolar mapping in atrial fibrillation
Time frame: Through study completion, an average of 1 year
Compare left atrial scar area between omnipolar and bipolar mapping in sinus rhythm
Time frame: Through study completion, an average of 1 year
Compare left atrial scar area in omnipolar maps between sinus rhythm and atrial fibrillation
Time frame: Through study completion, an average of 1 year
Compare left atrial scar areas in bipolar maps between sinus rhythm and atrial fibrillation
Time frame: Through study completion, an average of 1 year
Compare identification of pulmonary vein isolation gaps between omnipolar and bipolar maps
Time frame: Through study completion, an average of 1 year
Compare identification of pulmonary vein isolation gaps between sinus rhythm and atrial fibrillation
Time frame: Through study completion, an average of 1 year
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 18 May 2025.
- Individual participant dataSharing planned: No. No plans to share IPD
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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. This study is not recruiting at the moment.
Waqas Ullah, PhD principal investigator
University Hospital Southampton NHS Foundation Trust
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Mapping and ablation and Mapping in people with Atrial Fibrillation, run by University Hospital Southampton NHS Foundation 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 1 inclusion and 1 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: finished, as of the sponsor's last update on 18 May 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?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Scar Volume (time frame: Through study completion, an average of 1 year). 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 May 2025.