Research Highlights:
- Standard care, which included medication for those eligible, was better than a promising minimally invasive procedure for people with irregular heart rhythms who had high stroke and bleeding risk.
- The procedure seals off a small pouch of heart tissue, where most blood clots form in people with irregular heartbeat. However, in older people, standard care, including the use of blood thinners when indicated, did a better job at prevention of stroke, blood clots, cardiovascular or unexplained death or major bleeding than the procedure, according to the study conducted in Germany.
- Note: The study featured in this news release is a research abstract. Abstracts presented at American Heart Association's scientific meetings are not peer-reviewed, and the findings are considered preliminary until published as a full manuscript in a peer-reviewed scientific journal.
NEW ORLEANS, Nov. 8, 2025 — For older people with irregular heart rhythms who are at high risk of stroke and bleeding, standard care (including the use of blood thinners when indicated) was found to be the better choice compared to a promising, catheter-based procedure, according to a preliminary late-breaking science presentation today at the American Heart Association's Scientific Sessions 2025. The meeting, Nov. 7-10, in New Orleans, is a premier global exchange of the latest scientific advancements, research and evidence-based clinical practice updates in cardiovascular science.
The trial, Left Atrial Appendage CLOSURE in Patients with Atrial Fibrillation at High Risk of Stroke and Bleeding Compared to Medical Therapy (CLOSURE-AF), compared a catheter-based procedure to medical therapy among patients with an irregular heart rhythm known as atrial fibrillation or AFib.
An estimated five million people in the U.S. live with AFib, and it is predicted that more than 12 million people will have it by 2030, per the Association's 2025 Heart Disease and Stroke Statistics report.
While blood thinners can be highly effective at reducing the risk of stroke among people with AFib, the medication may cause severe bleeding in some people. Due to this risk, researchers are exploring alternative treatments including this catheter-based procedure. The procedure, called a left atrial appendage closure, seals a small pouch in the heart called the left atrial appendage, or LAA, where blood clots can form. If these blood clots enter the bloodstream, it increases the risk of stroke. Closing this pouch reduces the risk of stroke. It also can allow people to stop taking blood thinners for clot prevention.
The CLOSURE AF study compared catheter-based left atrial appendage closure with physician-directed standard medical care (including timely anticoagulant blood thinning when eligible) in patients with atrial fibrillation at high risk for stroke and bleeding. The aim of the study was to demonstrate non-inferiority for catheter-based LAA closure regarding risk of stroke, systemic embolism, cardiovascular/unexplained death or major bleeding. However, this was not reached.
"We expected that catheter-based LAA closure would be comparable to physician-directed standard medical care often using blood thinning anticoagulant medications," said study lead researcher Ulf Landmesser, M.D., chairman of the department of cardiology, angiology and intensive care medicine at Deutsche Herzzentrum Charité and professor of cardiology at Charité University Medicine in Berlin. "However, this was not the case in this trial of older patients at very high risk of bleeding and stroke.
"Our findings indicate that standard physician-directed medical care, including blood thinners for eligible patients, remains a valid management option for those older patients with irregular heartbeat who are at very high risk for stroke and bleeding."
Landmesser said that the results of the procedure are different for lower-risk patients, and studies investigating this are currently underway. Moreover, ongoing studies are comparing LAA closure in addition to blood thinning in very high-risk patients.
Because medical treatments and LAA closure for AFib remain in development the results of this study may not apply to future research, other techniques or procedures.
Study details, background and design:
- More than 900 adults with AFib who were at high risk of stroke and major bleeding participated in this study.
- Participants' average age was 78 years, and 39% were women.
- They were enrolled at 42 health care sites in Germany from March 2018 to April 2024, and they were followed for a median of 3 years.
- Participants were randomly assigned to one of two treatment groups: standard medical care (including anticoagulant blood thinners, if eligible); or LAA closure.
- Researchers compared the frequency of stroke, life-threatening blood clots, cardiovascular/unexplained death and major bleeding between the two treatment groups.
Co-authors, disclosures and funding sources are listed in the abstract.
Statements and conclusions of studies that are presented at the American Heart Association's scientific meetings are solely those of the study authors and do not necessarily reflect the Association's policy or position. The Association makes no representation or guarantee as to their accuracy or reliability. Abstracts presented at the Association's scientific meetings are not peer-reviewed, rather, they are curated by independent review panels and are considered based on the potential to add to the diversity of scientific issues and views discussed at the meeting. The findings are considered preliminary until published as a full manuscript in a peer-reviewed scientific journal.
