Comparing PFO Outcomes of the Occlutech Flex II PFO Occluder to Standard of Care PFO Occlusion (OCCLUFLEX)

May 21, 2026 updated by: Occlutech International AB

Prospective Randomized Multi-center Controlled Clinical Investigation Comparing Patent Foramen Ovale (PFO) Outcomes of the Occlutech Flex II PFO Occluder to Standard of Care PFO Occlusion

The objective of this study is to investigate whether percutaneous PFO closure with the Occlutech Flex II PFO Occluder is non-inferior to the AMPLATZER™ PFO Occluder and Gore® Cardioform Septal Occluder in closure of the PFO, prevention of recurrent embolic stroke, and device/procedure related Serious Adverse Events (SAE).

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Active, not recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
450

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Locations

  • Canada
    • Alberta
      • Edmonton, Alberta, Canada
        • University of Alberta Mazankowski Heart Institute
    • British Columbia
      • Vancouver, British Columbia, Canada
        • Vancouver General Hospital
    • Ontario
      • Ottawa, Ontario, Canada, K1Y 4W7
        • Ottawa Heart Institute
      • Toronto, Ontario, Canada
        • Toronto General Hospital
    • Quebec
      • Montreal, Quebec, Canada
        • Centre hospitalier de l'Université de Montréal (CHUM)
      • Montreal, Quebec, Canada
        • Institut de Cardiologie de Montreal
  • Denmark
      • Aarhus, Denmark
        • Aarhus University Hospital
      • Copenhagen, Denmark, 2100
        • Rigshospitalet Copenhagen
  • Finland
      • Helsinki, Finland
        • Heart and Lung Center, Helsinki University Hospital
  • France
      • La Tronche, France, 38700
        • CHU Grenoble Alpes
      • Massy, France, 91300
        • Hopital Prive Jacques Cartier
      • Toulouse, France, 31400
        • CHU TOULOUSE Rangueil
  • Germany
      • Frankfurt, Germany, 60389
        • CardioVasculäre Centrum Frankfurt
      • Heidelberg, Germany
        • Universitätsklinik Heidelberg
      • Lübeck, Germany, 23538
        • University Heart Center Lübeck
    • Free and Hanseatic City of Hamburg
      • Hamburg, Free and Hanseatic City of Hamburg, Germany, 20246
        • Universitaetsklinikum Hamburg-Eppendorf
      • Hamburg, Free and Hanseatic City of Hamburg, Germany, 22763
        • Asklepios Klinik Altona Hamburg
  • Netherlands
      • Amsterdam, Netherlands
        • Amsterdam University Medical Center
      • Rotterdam, Netherlands
        • Erasmus University Medical Centre
  • United Kingdom
      • Belfast, United Kingdom
        • Royal Victoria Hospital
    • East Sussex
      • Brighton, East Sussex, United Kingdom
        • University Hospitals Sussex
  • United States
    • Arizona
      • Phoenix, Arizona, United States, 85016
        • Arizona Cardiovascular Research Center
    • California
      • Stanford, California, United States, 94305
        • Stanford University Medical Center
      • Thousand Oaks, California, United States, 91360
        • Los Robles Medical Center
    • Colorado
      • Lakewood, Colorado, United States, 80228
        • Colorado Heart and Vascular PC / St. Anthony Hospital
      • Littleton, Colorado, United States, 80120
        • South Denver Cardiology Associates
    • District of Columbia
      • Washington D.C., District of Columbia, United States, 20010
        • Medstar Washington Hospital Center
    • Illinois
      • Chicago, Illinois, United States, 60612
        • Rush University Medical Center
      • Peoria, Illinois, United States, 61637
        • OSF Saint Francis Medical Center
    • Kentucky
      • Louisville, Kentucky, United States, 40202
        • University of Louisville
    • Maine
      • Portland, Maine, United States, 04102
        • MaineHealth
    • Massachusetts
      • Boston, Massachusetts, United States, 02215
        • Beth Israel Deaconess Medical Center
      • Boston, Massachusetts, United States, 02114
        • Massachusetts General Hospital
      • Boston, Massachusetts, United States, 02111
        • Tufts New England Medical Center
      • Springfield, Massachusetts, United States, 01199
        • Baystate Medical Center
    • Michigan
      • Ann Arbor, Michigan, United States, 48109
        • University of Michigan
    • Minnesota
      • Duluth, Minnesota, United States, 55804
        • Essentia Health
    • Nebraska
      • Omaha, Nebraska, United States, 68198
        • University of Nebraska Medical Center
    • New Jersey
      • Paramus, New Jersey, United States, 07652
        • The Valley Hospital
    • Ohio
      • Cleveland, Ohio, United States, 44106
        • University Hospitals Cleveland Medical Center
      • Columbus, Ohio, United States, 43210
        • The Ohio State University
      • Columbus, Ohio, United States, 43214
        • Ohio Health Research Institute
    • Oklahoma
      • Oklahoma City, Oklahoma, United States, 73120
        • Oklahoma Heart Hospital
    • Oregon
      • Portland, Oregon, United States, 97239
        • Oregon Health & Science University
    • Pennsylvania
      • Pittsburgh, Pennsylvania, United States, 15213
        • UPMC Presbyterian
    • Tennessee
      • Nashville, Tennessee, United States, 37232
        • Vanderbilt Medical Center
    • Texas
      • Houston, Texas, United States, 77030
        • University of Texas Health Science Center at Houston
      • Houston, Texas, United States, 77004
        • HCA Houston Healthcare Medical Center

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

18 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

No

Description

Inclusion Criteria: Subjects with a PFO and cryptogenic stroke:

  • PFO defined as visualization of microbubbles (during Trans Esophageal Echo (TEE)) in the left atrium within three cardiac cycles of right atrial opacification at rest and/or with Valsalva.
  • Cryptogenic stroke defined as a stroke of unknown cause.
  • Stroke defined as an acute focal neurological deficit, presumed to be due to focal ischemia, and either:
  • Symptoms persisting ≥24 hours OR
  • Symptoms persisting <24 hours with Magnetic Resonance Imaging (MRI) or Computer Tomography (CT) findings of a new, neuroanatomically relevant, cerebral infarct.

Exclusion Criteria:

  • Age < 18 years
  • Myocardial Infarction (MI) or unstable angina within 6 months.
  • Severe mitral valve stenosis, severe aortic valve stenosis, or severe regurgitation.
  • Left Ventricle Ejection Fraction (LVEF) <35%.
  • Uncontrolled hypertension or diabetes mellitus despite medications.
  • Subjects contraindicated for aspirin or clopidogrel.
  • Presence of other comorbid conditions, or other medical, social, or psychological conditions that, in the investigator's opinion, could limit the subject's ability to participate in the clinical trial or to comply with follow up requirements, or impact the scientific soundness of the clinical trial results.
  • Qualifying stroke with Modified Rankin score >3.
  • Anatomy in which the device would interfere with intracardiac or vascular structures.
  • Life expectancy < 2 years.
  • Participation in another clinical study that can interfere with the results of this study
  • Exclusion for patients with known causes of ischemic stroke:
  • Atrial fibrillation/atrial flutter (chronic or intermittent).
  • Left Ventricle (LV) aneurysm, intracardiac thrombus, or tumor.
  • Mitral or aortic valve vegetation or prosthesis.
  • Aortic arch plaques protruding >4 mm into the lumen.
  • Atherosclerosis or arteriopathy of intra- or extracranial vessels with >50% diameter stenosis in the artery supplying the infarcted territory.
  • Another cause of right-to-left shunting (e.g., an Atrial Septal Defect (ASD) or a fenestrated atrial septum).
  • Presence of an arterial hypercoagulable state.
  • Lacunar infarct probably due to intrinsic small vessel as the qualifying event, defined as an ischemic stroke in the distribution of a single, small deep penetrating vessel in a patient with any of the following:
  • A history of hypertension (except in the first week post stroke).
  • A history of diabetes mellitus.
  • Age ≥50 years.
  • MRI or CT with leukoaraiosis greater than symmetric, well-defined periventricular caps, or bands (European Task Force on Age-Related White Matter Changes rating scale score >0).
  • Arterial dissection as the qualifying event.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Single

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: Investigational PFO Closure Device
PFO closure with the study Occlutech Flex II PFO device.
Device: Investigational PFO Closure Device
Occlutech Flex II PFO Closure Device
Active Comparator: Standard of Care PFO Closure Device
PFO closure with either of the standard of care PFO occlusion devices; Amplatzer PFO Occluder or the Gore Cardioform PFO Occluder.
Device: Standard of Care PFO Closure Device
Amplatzer PFO Occluder and Gore Cardioform PFO Occluder

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Time Frame
Effective Closure Rate of PFO
Time Frame: Twelve Months
Twelve Months

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Time Frame
Non-Fatal Recurrent Stroke
Time Frame: Enrollment to 12 Months
Enrollment to 12 Months

Other Outcome Measures

Other Outcome Measures

For clinical trials, a planned measurement described in the protocol that is used to determine the effect of an intervention/treatment on participants. For observational studies, a measurement or observation that is used to describe patterns of diseases or traits, or associations with exposures, risk factors, or treatment. Types of outcome measures include primary outcome measure and secondary outcome measure.
Outcome Measure
Time Frame
Safety: Device and Procedure Related Serious Adverse Events
Time Frame: Enrollment to Twelve Months, Annually thereafter.
Enrollment to Twelve Months, Annually thereafter.

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Occlutech International AB

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Study Chair: David Thaler, MD, PhD, FAHA, Tufts Medical Center and Tufts University School of Medicine
  • Study Chair: Steven Yakubov, MD, FACC, MSCAI, OhioHealth Heart & Vascular

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
May 9, 2022

Primary Completion (Actual)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
November 30, 2025

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
November 1, 2029

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
September 24, 2021

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
September 24, 2021

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
October 6, 2021

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
May 22, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
May 21, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
August 1, 2025

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • OCC2021_02

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

Yes

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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