Non-valvular Atrial Fibrillation (AF)NCT05567172
Watchman FLX Pro CT Pilot Study
A study testing Left atrial appendage closure device WM FLX Pro in people with Non-valvular Atrial Fibrillation (AF), run by Boston Scientific Corporation at 1 site in Denmark.
Trial summary
The primary objective of this study is to measure device tissue coverage post-implantation of the WATCHMAN FLX™ Pro Left Atrial Appendage Closure (LAAC) Device (WATCHMAN FLX Pro) using the serial advanced imaging modalities of cardiac computed tomography (CT) and transesophageal echocardiography (TEE) and assess its… Read more about this study
- Who is it for?
- Ages 18 to 90 years
- Conditions the study is for
- Non-valvular Atrial Fibrillation (AF)
- What is being tested?
- Left atrial appendage closure device WM FLX Pro
- Type of treatment
- Medical device
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 43 participants
- Where
- 1 siteDenmark
- Study dates
- 24 Mar 2023to 18 Jun 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 to 90 years
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Subject is of legal age to participate in the study per the laws of their respective geography.
- Subject has documented non-valvular atrial fibrillation (i.e., atrial fibrillation in the absence of moderate or greater mitral stenosis or a mechanical heart valve).
- Subject is clinically indicated for a WATCHMAN FLX Pro device.
- Subject is deemed suitable for the protocol-defined pharmacologic regimen.
- Subject or legal representative is able to understand and willing to provide written informed consent to participate in the study.
- Subject is able and willing to return for required follow-up visits and examinations.
Who cannot join
- Subject is currently enrolled in another investigational study, except if the subject is participating in a mandatory governmental registry, or a purely observational registry with no associated treatment.
- Subject has eGFR <30 mL/min (chronic kidney disease stage IV or stage V).
- Subject is contraindicated for TEE.
- Subject requires long-term anticoagulation therapy for reasons other than AF-related stroke risk reduction (e.g., due to an underlying hypercoagulable state).
- Subject had or is planning to have any cardiac or non-cardiac intervention or surgical procedure within 30 days prior to or 60 days after implant (including, but not limited to, cardioversion, percutaneous coronary intervention, cardiac ablation, cataract surgery, etc.).
- Subject had a prior stroke (of any cause, whether ischemic or hemorrhagic) or TIA within the 30 days prior to enrollment.
Show all 20Show fewer
- Subject had a prior major bleeding event per ISTH definitions within the 30 days prior to enrollment. Lack of resolution of related clinical sequelae or planned and pending interventions to resolve bleeding/bleeding source are a further exclusion regardless of timing of the bleeding event.
- Subject has an active bleed.
- Subject has a reversible cause for AF or has transient AF.
- Subject has no LAA or the LAA is surgically ligated.
- Subject has had a myocardial infarction (MI) documented in the clinical record as either a non-ST elevation MI (NSTEMI) or as an ST-elevation MI (STEMI), with or without intervention, within 30 days prior to enrollment.
- Subject has a history of atrial septal repair or has an atrial septal defect/patent foramen ovale (ASD/PFO) device.
- Subject has a known contraindication to percutaneous catheterization procedure.
- Subject has a cardiac tumor.
- Subject has signs/symptoms of acute or chronic pericarditis.
- Subject has an active infection.
- There is evidence of tamponade physiology.
- Subject has New York Heart Association Class IV congestive heart failure at the time of enrollment.
- Subject is of childbearing potential and is, or plans to become, pregnant during the time of the study (method of assessment per study physician's discretion).
- Subject has a documented life expectancy of less than 6 months.
Trial locations and contacts
1 site in 1 country.
About this study
Official title: A Pilot Study to Assess WATCHMAN FLX™ Pro Implants by Cardiac Computed Tomography, Magnetic Resonance Imaging and Transesophageal Echocardiography: WATCHMAN FLX Pro CT
The primary objective of this study is to measure device tissue coverage post-implantation of the WATCHMAN FLX™ Pro Left Atrial Appendage Closure (LAAC) Device (WATCHMAN FLX Pro) using the serial advanced imaging modalities of cardiac computed tomography (CT) and transesophageal echocardiography (TEE) and assess its relationship, if any, to clinical events.
Read the detailed description
WATCHMAN FLX™ Pro CT is a prospective, single-arm, single-center, premarket investigation to assess device tissue coverage in subjects with non-valvular atrial fibrillation (AF) who receive the WATCHMAN FLX Pro device to reduce the risk of stroke. Serial advanced imaging modalities such as CT and TEE will be used. A core laboratory will independently assess select results.
A subject is considered enrolled in the study when the subject or the subject's legally authorized representative signs an Informed Consent Form (ICF) approved by the Independent Ethics Committee (IEC). Up to 50 subjects in whom placement of a WATCHMAN FLX Pro device is attempted will be enrolled.
A baseline assessment including TEE and/or CT imaging with optional cardiac magnetic resonance imaging (MRI) will be done within 7 days prior to the index procedure following core laboratory guidelines. Follow-up clinical assessment and imaging will occur at 14 days, 45 days, and 3 months post index procedure; only clinical assessment will be required at 12 months (unless an in-person assessment is required based on other data). Subjects who are enrolled but not implanted with a WATCHMAN FLX Pro LAAC device will be followed for safety through 12 months after the initial attempted index procedure but will not undergo imaging assessments or evaluation of biochemical markers including measures of coagulation, platelet and endothelial activation and inflammation.
- Conditions
- Non-valvular Atrial Fibrillation (AF)
- Being tested
- Left atrial appendage closure device WM FLX Pro
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Left atrial appendage closure device WM FLX ProDevice
Left atrial appendage closure
| Study group | Role | What they receive |
|---|---|---|
| Watchman FLX Pro | Experimental | Not described Receives: Device: Left atrial appendage closure device WM FLX Pro |
What is being measured
The primary outcome is the main question the study is designed to answer.
Number of Participants With Any Hypoattenuated Thickening (HAT) on the Surface of the Device
Serial measurement of any HAT on the surface of the device at 14 days, 45 days and 3 months post implant as assessed by core lab using CT imaging
Measured: 14 days to 3 months post implant
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted5 Oct 2022
- Study start24 Mar 2023
- Primary completion14 Oct 2024
- Study completion18 Jun 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 Non-valvular Atrial Fibrillation (AF)Studies of the same condition, open and under way.
- More trials run by Boston Scientific CorporationThe 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
- Masking
- None (open label)
- Enrolment
- 43 participants (actual)
Sponsor and investigators
- Lead sponsor
- Boston Scientific Corporation
- Sponsor type
- Industry (pharma, biotech, devices)
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05567172
- Sponsor's protocol ID
- S2517
- Status last verified
- Dec 2025
- First submitted
- 29 Sep 2022
- Last updated
- 9 Dec 2025
- Results posted
- Yes, on ClinicalTrials.gov
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Undecided
Study at a glance
From the registry record, last updated by the sponsor on 9 Dec 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- A Pilot Study to Assess WATCHMAN FLX™ Pro Implants by Cardiac Computed Tomography, Magnetic Resonance Imaging and Transesophageal Echocardiography: WATCHMAN FLX Pro CT
- ClinicalTrials.gov ID
- NCT05567172
- Acronym / sponsor ID
- S2517
- Conditions
- Non-valvular Atrial Fibrillation (AF)
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 43 participants (actual)
- Lead sponsor
- Boston Scientific CorporationIndustry (pharma, biotech, devices)
- Study start
- 24 Mar 2023 (actual)
- Primary completion
- 14 Oct 2024 (actual)
- Study completion
- 18 Jun 2025 (actual)
- First posted
- 5 Oct 2022 (actual)
- Results
- Posted 9 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 primary objective of this study is to measure device tissue coverage post-implantation of the WATCHMAN FLX™ Pro Left Atrial Appendage Closure (LAAC) Device (WATCHMAN FLX Pro) using the serial advanced imaging modalities of cardiac computed tomography (CT) and transesophageal echocardiography (TEE) and assess its relationship, if any, to clinical events.
Detailed description
WATCHMAN FLX™ Pro CT is a prospective, single-arm, single-center, premarket investigation to assess device tissue coverage in subjects with non-valvular atrial fibrillation (AF) who receive the WATCHMAN FLX Pro device to reduce the risk of stroke. Serial advanced imaging modalities such as CT and TEE will be used. A core laboratory will independently assess select results.
A subject is considered enrolled in the study when the subject or the subject's legally authorized representative signs an Informed Consent Form (ICF) approved by the Independent Ethics Committee (IEC). Up to 50 subjects in whom placement of a WATCHMAN FLX Pro device is attempted will be enrolled.
A baseline assessment including TEE and/or CT imaging with optional cardiac magnetic resonance imaging (MRI) will be done within 7 days prior to the index procedure following core laboratory guidelines. Follow-up clinical assessment and imaging will occur at 14 days, 45 days, and 3 months post index procedure; only clinical assessment will be required at 12 months (unless an in-person assessment is required based on other data). Subjects who are enrolled but not implanted with a WATCHMAN FLX Pro LAAC device will be followed for safety through 12 months after the initial attempted index procedure but will not undergo imaging assessments or evaluation of biochemical markers including measures of coagulation, platelet and endothelial activation and inflammation.
Study design
- Primary purpose
- Treatment
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| Watchman FLX Pro | Experimental | Device: Left atrial appendage closure device WM FLX Pro |
Who may qualify
- Ages
- 18 to 90 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (6 listed)
- Subject is of legal age to participate in the study per the laws of their respective geography.
- Subject has documented non-valvular atrial fibrillation (i.e., atrial fibrillation in the absence of moderate or greater mitral stenosis or a mechanical heart valve).
- Subject is clinically indicated for a WATCHMAN FLX Pro device.
- Subject is deemed suitable for the protocol-defined pharmacologic regimen.
- Subject or legal representative is able to understand and willing to provide written informed consent to participate in the study.
Key exclusion criteria (20 listed)
- Subject is currently enrolled in another investigational study, except if the subject is participating in a mandatory governmental registry, or a purely observational registry with no associated treatment.
- Subject has eGFR <30 mL/min (chronic kidney disease stage IV or stage V).
- Subject is contraindicated for TEE.
- Subject requires long-term anticoagulation therapy for reasons other than AF-related stroke risk reduction (e.g., due to an underlying hypercoagulable state).
- Subject had or is planning to have any cardiac or non-cardiac intervention or surgical procedure within 30 days prior to or 60 days after implant (including, but not limited to, cardioversion, percutaneous coronary intervention, cardiac ablation, cataract surgery, etc.).
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 |
|---|---|---|
| Left atrial appendage closure device WM FLX ProLeft atrial appendage closure | Device | Watchman FLX Pro |
Primary outcome
Number of Participants With Any Hypoattenuated Thickening (HAT) on the Surface of the Device
Time frame: 14 days to 3 months post implant
Serial measurement of any HAT on the surface of the device at 14 days, 45 days and 3 months post implant as assessed by core lab using CT imaging
Results and safety
Loading the posted results from ClinicalTrials.gov…
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 9 Dec 2025.
- Posted resultsParticipant flow, baseline, all outcome measures and adverse events.
- Individual participant dataSharing planned: Undecided
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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.
The record lists no contact. Use the official record to reach the sponsor.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Left atrial appendage closure device WM FLX Pro in people with Non-valvular Atrial Fibrillation (AF), run by Boston Scientific Corporation at 1 site in Denmark.
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 6 inclusion and 20 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 9 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 Denmark. 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 9 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?
Number of Participants With Any Hypoattenuated Thickening (HAT) on the Surface of the Device (time frame: 14 days to 3 months post implant). 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 9 Dec 2025; AzTrials last refreshed its copy on 27 Oct 2026.