Could a tiny implant replace daily blood thinners for AF patients?

NCT ID NCT03795298

Disease control Sponsor: Boston Scientific Corporation Source: ClinicalTrials.gov ↗

First seen Jun 25, 2026 · Last updated Jun 26, 2026 · Updated 1 time

Summary

This study tested whether a device called WATCHMAN FLX, which closes a small pouch in the heart, is a good alternative to blood thinners for preventing strokes in people with atrial fibrillation (AF) after a heart procedure called ablation. About 1,600 high-risk patients were enrolled. The goal was to see if the device could reduce strokes, deaths, and bleeding compared to standard blood thinner medications.

What this could mean

Our plain-language read of the trial. This is informational only, not medical advice or a prediction.

Active substance: WATCHMAN FLX Implant (a device that closes the left atrial appendage to prevent strokes)
What this could lead to: If successful, this could offer a long-term alternative to daily blood thinners for stroke prevention in atrial fibrillation patients after ablation.
What could go wrong: This is a completed trial, but results are not yet widely available. The device procedure carries risks like bleeding or complications, and it may not be suitable for all patients.

This is an AI summary of the original study and may miss details. Read our disclaimer.

Study facts

What this study's own registry entry says, in plain language.

Phase

Not a phased trial

Phase numbers describe drug development. The registry uses this when they do not apply, as it does for trials of devices, procedures or behaviour changes, and for observational studies.

Participants

1,600 people

The number who actually took part.

Started

May 2019

Finished

Jul 2024

Lead sponsor

A company

The lead sponsor is a pharmaceutical, biotech, or medical-device company.

Who can take part

This study's own entry requirements. Only the study team can say for certain whether you qualify.

Ages

18 years and older

Sex

Anyone

Healthy volunteers

Not accepted

This study is not open to healthy volunteers. The entry requirements below say who it is open to.

Show the full entry requirements

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: 1. The subject is of legal age to participate in the study per the laws of their respective geography. 2. Underwent a prior catheter ablation procedure for non-valvular AF between 90 and 180 days prior to randomization (sequential) or is planning to have clinically indicated catheter ablation within 10 days of randomization (concomitant). 3. The subject has a calculated CHA2DS2-VASc score of 2 or greater for males or 3 or greater for females. 4. The subject is deemed to be suitable for the defined protocol pharmacologic regimen. 5. The subject is able to undergo TEE examinations. 6. The subject or legal representative is able to understand and is willing to provide written informed consent to participate in the trial. 7. The subject is able and willing to return for required follow-up visits and examinations. Exclusion Criteria: 1. The subject is currently enrolled in another investigational study that would directly interfere with the current study, except when the subject is participating in a mandatory governmental registry, or a purely observational registry with no associated treatments. Each instance must be brought to the attention of the sponsor to determine eligibility, regardless of type of co-enrollment being proposed. 2. The subject requires long-term anticoagulation therapy for reasons other than AF-related stroke risk reduction, for example due to an underlying hypercoagulable state (i.e., even if the device is implanted, the subjects would not be eligible to discontinue OAC due to other medical conditions requiring chronic OAC therapy). 3. The subject is deemed by the treating physician to be unsuitable for chronic anticoagulation and/or aspirin therapy due to bleeding risk, allergy, or other reasons. 4. The subject had or is planning to have any cardiac or major non-cardiac interventional or surgical procedure (excluding non-valvular AF ablation and cardioversion) within 30 days prior to or 60 days after randomization \[including, but not limited to: percutaneous coronary intervention (PCI), other cardiac ablation (VT ablation, etc.), etc.\]. 5. The subject had a stroke or transient ischemic attack (TIA) within the 60 days prior to randomization. 6. The subject had a prior major bleeding event per ISTH definition within the 14 days prior to randomization. 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. 7. The 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 90 days prior to randomization. 8. The subject has a history of atrial septal repair or has an ASD/PFO device. 9. The subject has an implanted mechanical valve prosthesis in any position. 10. The subject is of childbearing potential and is, or plans to become pregnant during the time of the study (method of assessment upon study physician's discretion) 11. The subject has a documented life expectancy of less than two years. 12. The subject has a cardiac tumor. 13. The subject has signs/symptoms of acute or chronic pericarditis. 14. There is evidence of tamponade physiology. 15. Contraindications (anatomical or medical) to percutaneous catheterization procedures. 16. The subject has documented NYHA Class IV heart failure. 17. The subject has documented surgical closure of the left atrial appendage. 18. The subject has an active infection.

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Conditions

The condition(s) this trial relates to.

atrial fibrillation

As listed by the trial registrant

The condition terms exactly as the trial's registrant entered them.

Atrial fibrillation

Contacts and locations

Locations

Aarhus University Hospital

Aarhus, 8200, Denmark
Abbott Northwestern Hospital

Minneapolis, Minnesota, 55407, United States
Advara HeartCare

Brisbane, Queensland, 4120 QLD, Australia
AdventHealth Ocala

Ocala, Florida, 34471, United States
Alaska Regional Hospital

Anchorage, Alaska, 99508, United States
Allgemeines Krankenhaus Altona

Hamburg, 22763, Germany
Arizona Arrhythmia Research Center

Phoenix, Arizona, 85016, United States
Asklepios Klinik Saint Georg

Hamburg, 20099, Germany
Azienda Ospedaliero-Universitaria Citta della Salute e della Scienza di Torino

Torino, 10123, Italy
Baptist Health Lexington

Lexington, Kentucky, 40503, United States
Broward General Medical Center

Fort Lauderdale, Florida, 33316, United States
CHI Franciscan Health System

Tacoma, Washington, 98405, United States
CHRU de Clermont-Ferrand

Clermont-Ferrand, 63000, France
CHRU de Lille

Lille, Hauts-de-France, 59037, France
CHU Grenoble - Hopital Michallon

Grenoble, 38043, France
CHU Henri Mondor

Créteil, Île-de-France Region, 94010, France
Cardioangiologisches Centrum Bethanien

Frankfurt, 60431, Germany
Cardiology Clinic of San Antonio

San Antonio, Texas, 78229, United States
Cardiovascular Associates of the Delaware Valley

Haddon Heights, New Jersey, 08035, United States
Carolinas Medical Center

Charlotte, North Carolina, 28203, United States
Catholic Medical Center

Manchester, New Hampshire, 03102, United States
Centennial Medical Center

Nashville, Tennessee, 37203, United States
Centre Hôpital Universitaire Rangueil

Toulouse, 31400, France
Centro Cardiologico Monzino

Milan, 20138, Italy
Centura Health

Littleton, Colorado, 80120, United States
Chippenham Medical Center

Richmond, Virginia, 23225, United States
Christus Trinity Mother Frances Health System

Tyler, Texas, 75702, United States
Cleveland Clinic Foundation

Cleveland, Ohio, 44195, United States
Clinico de Valladolid

Valladolid, 47005, Spain
Clinique Pasteur

Toulouse, 31076, France
DHZC - Deutsches Herzzentrum der Charité

Berlin, 12203, Germany
Duke University Medical Center

Durham, North Carolina, 27705, United States
Edward Hospital

Naperville, Illinois, 60540, United States
Emory University Hospital

Atlanta, Georgia, 30322, United States
Grandview Medical Center

Birmingham, Alabama, 35243, United States
HealthEast St. Joseph's Hospital

Saint Paul, Minnesota, 55102, United States
Heart Center Research

Huntsville, Alabama, 35801, United States
Heart Clinic Arkansas

Little Rock, Arkansas, 72205, United States
HeartPlace Mid-Cities EP

Bedford, Texas, 76021, United States
Henry Ford Hospital

Detroit, Michigan, 48202, United States
Hospital Alvaro Cunqueiro

Vigo, 36312, Spain
Hospital Clinico Salamanca

Salamanca, 37007, Spain
Hospital Clinico San Carlos

Madrid, 28040, Spain
Hospital Europeen Georges-Pompidou

Paris, 75015, France
Hospital General Universitario

Alicante, 3010, Spain
Hospital Puerta Del Mar

Cadiz, 11009, Spain
Hospital de la Pitie-Salpetriere

Paris, Île-de-France Region, 75013, France
Intermountain Medical Center

Murray, Utah, 84107, United States
Iowa Heart Center

Des Moines, Iowa, 50266, United States
Kaiser Permanente Santa Clara Medical Center

Santa Clara, California, 95051, United States
Kansas City Cardiac Arrhythmia Research

Overland Park, Kansas, 66215, United States
Klinik für Kardiologie, Angiologie und Intensivmedizin Mittelallee

Berlin, 13353, Germany
Klinikum Coburg GmbH

Coburg, 96450, Germany
Klinikum St. Georg

Leipzig, 4129, Germany
Lahey Clinic Hospital

Burlington, Massachusetts, 01805, United States
Lankenau Institute for Medical Research

Wynnewood, Pennsylvania, 19096, United States
Lindner Center for Research and Education at Christ Hospital

Cincinnati, Ohio, 45219, United States
Manatee Memorial Hospital

Bradenton, Florida, 34205, United States
Marian Regional Medical Center

Santa Maria, California, 93454, United States
Marin General Hospital

Larkspur, California, 94939, United States
Massachusetts General Hospital

Boston, Massachusetts, 02114, United States
Mayo Clinic

Rochester, Minnesota, 55905, United States
Medical Center of the Rockies (Loveland)

Loveland, Colorado, 80538, United States
Memorial Hospital

Colorado Springs, Colorado, 80909, United States
Mercy Research

St Louis, Missouri, 63141, United States
Methodist Hospital of Indianapolis

Indianapolis, Indiana, 46202, United States
Mills Peninsula Health Services

Burlingame, California, 94010, United States
Monash Health

Clayton, Victoria, 3168, Australia
Monongalia General Hospital

Morgantown, West Virginia, 26506, United States
Montefiore Medical Center

The Bronx, New York, 10467, United States
Mount Sinai Medical Center

New York, New York, 10029, United States
MyMichigan Medical Center Midland

Midland, Michigan, 48670, United States
Nebraska Heart Institute

Lincoln, Nebraska, 68526, United States
Nebraska Methodist Hospital

Omaha, Nebraska, 68114, United States
New York University Medical Center

New York, New York, 10016, United States
Northwell Health

Bay Shore, New York, 11706, United States
OhioHealth Research and Innovation Institute - Riverside Methodist Hospital

Columbus, Ohio, 43214, United States
Onze Lieve Vrouw Ziekenhuis

Aalst, East Flanders, 9300, Belgium
Overland Park Regional Medical Center

Kansas City, Kansas, 66160, United States
PeaceHealth Southwest Medical

Vancouver, Washington, 98664, United States
Phoenix Cardiovascular Research Group

Phoenix, Arizona, 85016, United States
Pinnacle Health at Harrisburg Hospital

Harrisburg, Pennsylvania, 17101, United States
Poznan University of Medical Sciences

Poznan, 61-848, Poland
Presbyterian University of Pennsylvania Medical Center

Philadelphia, Pennsylvania, 19104, United States
Rex Hospital

Raleigh, North Carolina, 27607, United States
Saint Thomas Health

Nashville, Tennessee, 37205, United States
Scripps Memorial Hospital

La Jolla, California, 92037, United States
Sharp Memorial Hospital

San Diego, California, 92123, United States
St. Alphonsus Regional Medical Center

Boise, Idaho, 83704, United States
St. Antonius Ziekenhuis

Nieuwegein, Utrecht, 3430 EM, Netherlands
St. Bernard's Medical Center

Jonesboro, Arkansas, 72401, United States
St. John's Hospital

Springfield, Illinois, 62701, United States
St. Josefs-Hospital GmbH

Wiesbaden, 65189, Germany
St. Luke's Hospital of Kansas City

Kansas City, Missouri, 64111, United States
St. Lukes Idaho Cardiology Associates

Boise, Idaho, 83712, United States
St. Mark's Hospital

Salt Lake City, Utah, 84124, United States
St. Vincent Heart Center of Indiana

Indianapolis, Indiana, 46290, United States
St. Vincent's Medical Center

Jacksonville, Florida, 32204, United States
St.Johann Nepomuk Katholisches Hospitalvereinigung Thüringen GmbH

Erfurt, 99097, Germany
Tallahassee Memorial Hospital

Tallahassee, Florida, 32308, United States
Texas Cardiac Arrhythmia Research

Austin, Texas, 78705, United States
The Heart Hospital Baylor Plano

Plano, Texas, 75093, United States
Universitaetsklinikum Schleswig-Holstein

Lübeck, D-23538, Germany
Universitatsklinik Greifswald

Greifswald, 17475, Germany
University of Kansas Hospital

Kansas City, Kansas, 66160, United States
University of Pittsburgh Medical Center

Pittsburgh, Pennsylvania, 15237, United States
University of Southern California Hospital

Los Angeles, California, 90017, United States
Valley Hospital

Ridgewood, New Jersey, 07450, United States
Vanderbilt University Medical Center

Nashville, Tennessee, 37232, United States
Washington Hospital Center

Washington D.C., District of Columbia, 20010, United States
Wellstar Kennestone Hospital

Marietta, Georgia, 30060, United States
West Virginia University Hospitals

Morgantown, West Virginia, 26506, United States
Yale University School of Medicine

New Haven, Connecticut, 06510, United States
York Hospital

York, Pennsylvania, 17403, United States

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