Atrial FibrillationBETTER-FITNCT05881733
Effect of a Bigger Cryoballoon on the Total Antral Lesion Size: Evaluation of POLARx FIT
A study testing POLARx FIT cryoballoon in people with Atrial Fibrillation, run by Erasmus Medical Center at 1 site in Netherlands.
Trial summary
The investigators will prospectively evaluate the extent of antral lesion created by the 31 mm balloon size of a novel cryoballoon catheter (POLARx FIT). In 20 patients with paroxysmal atrial fibrillation, the investigators will perform pre- and post-ablation high-definition 3D maps to quantify the extent of lesion… Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Atrial Fibrillation
- What is being tested?
- POLARx FIT cryoballoon
- Type of treatment
- Medical device
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 20 participants
- Where
- 1 siteNetherlands
- Study dates
- 2 Oct 2023to 23 Apr 2025
- Phase
- Interventional
- Are there results?
- Yes, posted in the registrySummary in the doctors' view
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
- History of symptomatic paroxysmal AF
- Subjects who are indicated for a PVI according to the 2020 ESC guidelines for the diagnosis and management of AF
- Subjects who are willing and capable of providing informed consent
- Subjects who are willing and capable of participating in all testing associated with this clinical investigation
- Subjects whose age is 18 years or above
Who cannot join
- Any known contraindication to an AF ablation or anticoagulation
- History of previous left atrial ablation or surgical treatment of AF, atrial flutter, or atrial tachycardia
- AF secondary to electrolyte imbalance, thyroid disease, or any other reversible or non-cardiac cause
- Significant structural heart disease as evidenced by:
- Left ventricular ejection fraction <45% based on most recent transthoracic echocardiogram (TTE) performed <6 months prior to enrollment
- LA diameter >55 mm based on most recent TTE performed <6 months prior to enrollment
Show all 19Show fewer
- Previous cardiac surgery
- Previous cardiac valvular surgical or percutaneous procedure
- Interatrial baffle, closure device, patch, or occluder
- Unstable angina or ongoing myocardial ischemia
- Moderate or severe valvular heart disease on most recent TTE performed <6 months prior to enrolment
- Congenital heart disease
- Left atrial thrombus
- History of blood clotting or bleeding disease
- Stroke or transient ischemic attack <3 months prior to enrollment
- Active systemic infection
- Common ostium PV >24 mm defined by CT-scan
- Pregnant, lactating, or women of childbearing potential who are, or plan to become, pregnant during the time of the study
- Subjects who are currently enrolled in another investigational study or registry that would directly interfere with the current study
Trial locations and contacts
1 site in 1 country.
Netherlands1 site
Erasmus Medical Center
Rotterdam, South Holland, 3015 GD
About this study
The investigators will prospectively evaluate the extent of antral lesion created by the 31 mm balloon size of a novel cryoballoon catheter (POLARx FIT). In 20 patients with paroxysmal atrial fibrillation, the investigators will perform pre- and post-ablation high-definition 3D maps to quantify the extent of lesion created by the 31 mm POLARx FIT cryoballoon.
Read the detailed description
Rationale: The next generation POLARx cryoablation balloon (CB) catheter will have the option of to deliver cryotherapy with the current balloon size of 28 mm or a new, larger 31 mm size by changing the inner balloon pressure (POLARx FIT, Boston Scientific). Currently, there is no data on the extension of left atrial (LA) lesion formation with the 31 mm balloon size of the POLARx FIT cryoablation balloon catheter. The hypothesis is that a larger CB size results in a wide antral circumferential lesion.
Objective: The primary objective is to evaluate the antral lesion size using ultrahigh-density (UHDx) mapping pre- and post-cryoablation with the 31 mm balloon size CB. Secondary objectives are the proportion of pulmonary veins (PVs) where a 31 mm CB could be positioned to achieve a grade 4 occlusion and the single shot success rate with the 31 mm balloon size CB.
Study design: Single-center, single-arm, prospective study with pre- and post-PVI UHDx mapping.
Study population: Twenty adult patients with paroxysmal AF who are scheduled to undergo pulmonary vein isolation (PVI) with a CB.
Intervention: Patients will undergo pre- and post-ablation UHDx mapping (Orion catheter and Rhythmia 3D-mapping system, Boston Scientific) during the index procedure.
Main study parameters/endpoints: The primary endpoint is the extent of the antral lesion size. Secondary endpoints are the proportion of PVs with grade 4 occlusion with the 31 mm balloon size CB, the single shot success rate of the 31 mm balloon size CB, difference in rate of achieving grade 4 occlusion in comparison to the standard (28 mm) size.
Nature and extent of the burden and risks associated with participation, benefit, and group relatedness: A UHDx mapping will be acquired before and after complete PVI. The procedures will be performed under deep sedation, which is standard practice for CB procedures in our institution. The risk of additional mapping is limited. LA mapping is a standard diagnostic method for patients undergoing PVI with radiofrequency ("standard-of-care"). In the current study, UHDx mapping will now be used in patients undergoing PVI with CB. The most important complication of additional intracardiac mapping is cardiac tamponade, but this risk is low (<0.5%).
- Conditions
- Atrial Fibrillation
- Being tested
- POLARx FIT cryoballoon
- Keywords
- Cryoballoon, Atrial fibrillation
- Medical subject headings
- Atrial Fibrillation
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
POLARx FIT cryoballoonDevice
Patients will undergo cryoablation with the 31 mm balloon size of the POLARx FIT cryoballoon.
| Study group | Role | What they receive |
|---|---|---|
| Study population | Other | This study will have only a single arm. Patients will undergo pulmonary vein isolation using the 31 mm balloon size of POLARx FIT. High-definition 3D maps will be constructed before and after cryoablation to assess the antral lesion size. Receives: Device: POLARx FIT cryoballoon |
What is being measured
The primary outcome is the main question the study is designed to answer.
Percentage of Ablated Left Atrial Posterior Wall With a 31 mm Balloon Size POLARx FIT
Low-voltage areas will be quantified using a bipolar voltage <0.3 mV. The sum of the posterior ablated areas of all pulmonary veins is expressed as a percentage of the total left atrial posterior wall.
Measured: Interprocedural (directly after cryoablation)
Secondary outcomes (2)
Percentage of Pulmonary Veins With Grade 4 Occlusion With a 31 mm Balloon Size POLARx FIT
A grade 4 occlusion is defined as complete contrast stasis. Cine acquisitions of contrast vein occlusions was analyzed by two experienced observers.
Measured: Interprocedural (before cryoablation)
Percentage of Pulmonary Veins With a Single Shot Success Rate Using a 31 mm Balloon Size POLARx FIT Cryoablation Catheter
Pulmonary vein isolation will be determined using conventional criteria: entry- and exit-block as assessed with the circular mapping catheter (POLARMAP).
Measured: Interprocedural (directly after cryoablation)
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted31 May 2023
- Study start2 Oct 2023
- Primary completion29 Apr 2024
- Study completion23 Apr 2025
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Posted resultsParticipant flow, outcome measures and adverse events reported by the sponsor.
- Other trials for Atrial FibrillationStudies of the same condition, open and under way.
- More trials run by Erasmus Medical CenterThe sponsor's other registered studies.
- 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
- Treatment
- Allocation
- Not applicable
- Intervention model
- Single group
- Model description
- Prospective, single-arm, single-center, study
- Masking
- None (open label)
- Enrolment
- 20 participants (actual)
Sponsor and investigators
- Lead sponsor
- Erasmus Medical Center
- Sponsor type
- University, hospital or other
- Collaborators
- Boston Scientific Corporation
- Responsible party
- Principal investigator, Sing-Chien Yap, MD, PhD, Erasmus Medical Center
- Investigators
- Sing-Chien Yap, MD, PhD, Principal investigator, Erasmus Medical Center
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05881733
- Sponsor's protocol ID
- MEC-2023-0325
- Other IDs
- NL84423.078.23
- Acronym
- BETTER-FIT
- Status last verified
- Nov 2025
- First submitted
- 21 May 2023
- Last updated
- 4 Dec 2025
- Results posted
- Yes, on ClinicalTrials.gov
- 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 4 Dec 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Effect of a Bigger Cryoballoon on the Total Antral Lesion Size: Evaluation of POLARx FIT
- ClinicalTrials.gov ID
- NCT05881733
- Acronym / sponsor ID
- BETTER-FIT / MEC-2023-0325
- Conditions
- Atrial Fibrillation
- Keywords
- Cryoballoon, Atrial fibrillation
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 20 participants (actual)
- Lead sponsor
- Erasmus Medical CenterUniversity, hospital or other
- Collaborators
- Boston Scientific Corporation
- Study start
- 2 Oct 2023 (actual)
- Primary completion
- 29 Apr 2024 (actual)
- Study completion
- 23 Apr 2025 (actual)
- First posted
- 31 May 2023 (actual)
- Results
- Posted 4 Dec 2025
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The investigators will prospectively evaluate the extent of antral lesion created by the 31 mm balloon size of a novel cryoballoon catheter (POLARx FIT). In 20 patients with paroxysmal atrial fibrillation, the investigators will perform pre- and post-ablation high-definition 3D maps to quantify the extent of lesion created by the 31 mm POLARx FIT cryoballoon.
Detailed description
Rationale: The next generation POLARx cryoablation balloon (CB) catheter will have the option of to deliver cryotherapy with the current balloon size of 28 mm or a new, larger 31 mm size by changing the inner balloon pressure (POLARx FIT, Boston Scientific). Currently, there is no data on the extension of left atrial (LA) lesion formation with the 31 mm balloon size of the POLARx FIT cryoablation balloon catheter. The hypothesis is that a larger CB size results in a wide antral circumferential lesion.
Objective: The primary objective is to evaluate the antral lesion size using ultrahigh-density (UHDx) mapping pre- and post-cryoablation with the 31 mm balloon size CB. Secondary objectives are the proportion of pulmonary veins (PVs) where a 31 mm CB could be positioned to achieve a grade 4 occlusion and the single shot success rate with the 31 mm balloon size CB.
Study design: Single-center, single-arm, prospective study with pre- and post-PVI UHDx mapping.
Study population: Twenty adult patients with paroxysmal AF who are scheduled to undergo pulmonary vein isolation (PVI) with a CB.
Intervention: Patients will undergo pre- and post-ablation UHDx mapping (Orion catheter and Rhythmia 3D-mapping system, Boston Scientific) during the index procedure.
Main study parameters/endpoints: The primary endpoint is the extent of the antral lesion size. Secondary endpoints are the proportion of PVs with grade 4 occlusion with the 31 mm balloon size CB, the single shot success rate of the 31 mm balloon size CB, difference in rate of achieving grade 4 occlusion in comparison to the standard (28 mm) size.
Nature and extent of the burden and risks associated with participation, benefit, and group relatedness: A UHDx mapping will be acquired before and after complete PVI. The procedures will be performed under deep sedation, which is standard practice for CB procedures in our institution. The risk of additional mapping is limited. LA mapping is a standard diagnostic method for patients undergoing PVI with radiofrequency ("standard-of-care"). In the current study, UHDx mapping will now be used in patients undergoing PVI with CB. The most important complication of additional intracardiac mapping is cardiac tamponade, but this risk is low (<0.5%).
Study design
- Primary purpose
- Treatment
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 1
- Model description
- Prospective, single-arm, single-center, study
| Arm | Type | Receives |
|---|---|---|
| Study population | Other | Device: POLARx FIT cryoballoonThis study will have only a single arm. Patients will undergo pulmonary vein isolation using the 31 mm balloon size of POLARx FIT. High-definition 3D maps will be constructed before and after cryoablation to assess the antral lesion size. |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (5 listed)
- History of symptomatic paroxysmal AF
- Subjects who are indicated for a PVI according to the 2020 ESC guidelines for the diagnosis and management of AF
- Subjects who are willing and capable of providing informed consent
- Subjects who are willing and capable of participating in all testing associated with this clinical investigation
- Subjects whose age is 18 years or above
Key exclusion criteria (19 listed)
- Any known contraindication to an AF ablation or anticoagulation
- History of previous left atrial ablation or surgical treatment of AF, atrial flutter, or atrial tachycardia
- AF secondary to electrolyte imbalance, thyroid disease, or any other reversible or non-cardiac cause
- Significant structural heart disease as evidenced by:
- History of blood clotting or bleeding disease
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 |
|---|---|---|
| POLARx FIT cryoballoonPatients will undergo cryoablation with the 31 mm balloon size of the POLARx FIT cryoballoon. | Device | Study population |
Primary outcome
Percentage of Ablated Left Atrial Posterior Wall With a 31 mm Balloon Size POLARx FIT
Time frame: Interprocedural (directly after cryoablation)
Low-voltage areas will be quantified using a bipolar voltage <0.3 mV. The sum of the posterior ablated areas of all pulmonary veins is expressed as a percentage of the total left atrial posterior wall.
2 secondary outcomes
Percentage of Pulmonary Veins With Grade 4 Occlusion With a 31 mm Balloon Size POLARx FIT
Time frame: Interprocedural (before cryoablation)
Percentage of Pulmonary Veins With a Single Shot Success Rate Using a 31 mm Balloon Size POLARx FIT Cryoablation Catheter
Time frame: Interprocedural (directly after cryoablation)
Results and safety
Loading the posted results from ClinicalTrials.gov…
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 4 Dec 2025.
- Posted resultsParticipant flow, baseline, all outcome measures and adverse events.
- Individual participant dataSharing planned: No
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Atrial Fibrillation (AF)
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.
Sing-Chien Yap, MD, PhD principal investigator
Erasmus Medical Center
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing POLARx FIT cryoballoon in people with Atrial Fibrillation, run by Erasmus Medical Center at 1 site in Netherlands.
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 5 inclusion and 19 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 4 Dec 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 Netherlands. 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?
Yes. Results are posted in the registry (first posted 4 Dec 2025). A summary is in the For doctors view, and the full results are on ClinicalTrials.gov.
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?
Percentage of Ablated Left Atrial Posterior Wall With a 31 mm Balloon Size POLARx FIT (time frame: Interprocedural (directly after cryoablation)). 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 4 Dec 2025.