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Wildfire smoke blankets the Seattle skyline in 2020. A new study finds that pregnant people who are exposed to wildfire smoke are more likely to give birth prematurely.

About 10% of American babies are born prematurely. Birth before 37 weeks can lead to a cascade of health risks, both immediate and long-term, making prevention a vital tool for improving public health over generations. 

In recent years, researchers have identified a potential link between wildfire smoke — one of the fastest-growing sources of air pollution in the United States — and preterm birth, but no study has been big or broad enough to draw definitive conclusions. A new study led by the University of Washington makes an important contribution, analyzing data from more than 20,000 births to find that pregnant people who are exposed to wildfire smoke are more likely to give birth prematurely.

“Preventing preterm birth really pays off with lasting benefits for future health,” said lead author Allison Sherris, a UW postdoctoral researcher in environmental and occupational health sciences. “It’s also something of a mystery. We don’t always understand why babies are born preterm, but we know that air pollution contributes to preterm births, and it makes sense that wildfire smoke would as well. This study underscores that wildfire smoke is inseparable from maternal and infant health.”

In the study, published Nov. 3 in The Lancet Planetary Health, researchers used data from the Environmental influences on Child Health Outcomes (ECHO) program, a federal research project focused on how a wide range of environmental factors affect children’s health. The sample included 20,034 births from 2006-2020 across the contiguous United States.

Researchers estimated participants’ average daily exposure to fine particulate matter, or PM2.5, generated by wildfire smoke, and the total number of days they were exposed to any amount of smoke. They estimated the intensity of smoke exposure by how frequently participants were exposed to wildfire PM2.5 levels above certain thresholds.

They found that pregnant people exposed to more intense wildfire smoke were more likely to give birth prematurely. In mid-pregnancy, exposure to any smoke was associated with an elevated risk of preterm birth, with that risk peaking around the 21st week of gestation. In late pregnancy, elevated risk was most closely associated with exposure to high concentrations of wildfire PM2.5, above 10 micrograms per cubic meter.

“The second trimester is a period of pregnancy with the richest and most intense growth of the placenta, which itself is such an important part of fetal health, growth and development,” said co-author Dr. Catherine Karr, a UW professor of environmental and occupational health sciences and of pediatrics in the UW School of Medicine. “So it may be that the wildfire smoke particles are really interfering with placental health. Some of them are so tiny that after inhalation they can actually get into the bloodstream and get delivered directly into the placenta or fetus.” 

The link was strongest and most precise in the Western U.S., where people were exposed to the highest concentrations of wildfire PM2.5 and the greatest number of high-intensity smoke days. Here, the odds of preterm birth increased with each additional microgram per cubic meter of average wildfire PM2.5.

It’s possible those results were more precise simply because the West experiences more wildfire smoke on average, making the exposure model perform better, Sherris said. But there may be other factors behind the regional differences. 

The composition of wildfire smoke is different across the country. In the West, smoke tends to come from fires nearby, while in places like the Midwest, smoke has typically drifted in from faraway fires. Smoke’s toxicity changes as it ages and reacts with sunlight and airborne chemicals, which could have affected the results. Researchers also noted that external factors like co-occurring heat or housing quality may have effects that aren’t fully understood. 

Researchers hope that future studies will examine the exact mechanisms by which wildfire smoke might trigger preterm birth. But in the meantime, Sherris said, evidence for a link is now strong enough to take action. 

“There are a couple avenues for change,” Sherris said. “First, people already get a lot of public health messaging and information throughout pregnancy, so there’s an opportunity to work with clinicians to provide tools for pregnant people to protect themselves during smoke events. Public health agencies’ messaging about wildfire smoke could also be tailored to pregnant people and highlight them as a vulnerable group.”

Co-authors include Logan Dearborn, doctoral student of environmental and occupational health sciences at the UW; Christine Loftus, clinical associate professor of environmental and occupational health sciences at the UW; Adam Szpiro, professor of biostatistics at the UW; Joan Casey, associate professor of environmental and occupational health sciences and of epidemiology at the UW; Sindana Ilango, postdoctoral fellow of epidemiology at the UW; and Marissa Childs, assistant professor of environmental and occupational health sciences at the UW. A full list of co-authors is included with the paper.

This research was funded by the Environmental influences on Child Health Outcomes (ECHO) program at the National Institutes of Health under multiple awards. A full list of ECHO funding awards is included with the paper. 

For more information or to contact the researchers, email Alden Woods at acwoods@uw.edu.

Therapies that are sensitive to multiple biomarkers could allow medicines to reach only the areas of the body where they are needed. The diagram above shows three theoretical biomarkers that are present in specific, sometimes overlapping areas of the body. A therapy designed to find the unique area of overlap between the three will act on only that area.DeForest et al./Nature Chemical Biology

Targeted drug delivery is a powerful and promising area of medicine. Therapies that pinpoint the exact areas of the body where they’re needed — and nowhere they’re not — can reduce the medicine dosage and avoid potentially harmful “off target” effects elsewhere in the body. A targeted immunotherapy, for example, might seek out cancerous tissues and activate immune cells to fight the disease only in those tissues.

The tricky part is making a therapy truly “smart,” where the medicine can move freely through the body and decide which areas to target.

Researchers at the University of Washington took a significant step toward that goal by designing proteins with autonomous decision-making capabilities. In a proof-of-principles study published Oct. 9 in Nature Chemical Biology, researchers demonstrated that by adding smart tail structures to therapeutic proteins, they could control the proteins’ localization based on the presence of specific environmental cues. These protein tails fold themselves into preprogrammed shapes that define how they react to different combinations of cues. In addition, the experiment showed that the smart protein tails could be attached to a carrier material for delivery to living cells.

Advances in synthetic biology also allowed the researchers to manufacture these proteins cheaply and in a matter of days instead of months.

“We’ve been thinking about these concepts for some time but have struggled with ways to increase and automate production,” said senior author Cole DeForest, a UW professor of chemical engineering and bioengineering. “We’ve now finally figured out how to produce these systems faster, at scale and with dramatically enhanced logical complexity. We are excited about how these will lead to more sophisticated and scalable disease-honing therapies.”

The concept of programmable biomaterials isn’t new. Scientists have developed numerous strategies to make systems responsive to individual cues — such as pH levels or the presence of specific enzymes — that are associated with a particular disease or area of the body. But it’s rare to find one cue, or “biomarker,” that’s unique to one spot, so a material that hones in on just one biomarker might act on a few unintended places in addition to the target.

One solution to this problem is to seek out a combination of biomarkers. There might be many areas of the body with particular enzyme or pH levels, but there are likely fewer areas with both of those factors. In theory, the more biomarkers a material can identify, the more finely targeted drug delivery can be.

In 2018, DeForest’s lab created a new class of materials that responded to multiple biomarkers using Boolean logic, a concept traditionally used in computer programming.

The diagrams above show linker structures that can perform different logical operations. In box 1, the protein therapeutic (star) is released from a material (pink wedge) in the presence of either biomarker X or Y; in box 2, the protein will release only if both biomarkers X and Y are present.DeForest et al./Nature Chemical Biology

“We realized that we could program how therapeutics were released based simply on how they were connected to a carrier material,” DeForest said. “For example, if we linked a therapeutic cargo to a material via two degradable groups connected in series — that is, each after the other — it would be released if either group was degraded, acting as an OR gate. When the degradable groups were instead connected in parallel — that is, each on a different half of a cycle — both groups had to be degraded for cargo release, functioning as an AND gate. Excitingly, by combining these basic gates we could readily create advanced logical circuits.”

It was a big step forward, but it wasn’t scalable — the team built these large and complex logic-responsive materials manually through traditional organic chemistry.

But over the next several years, the related field of synthetic biology advanced by leaps and bounds.

“The field has developed exciting new protein-based tools that can allow researchers to form permanent bonds between proteins,” said co-first author Murial Ross, a UW doctoral student of bioengineering. “It opened doors for new protein structures that were previously unachievable, which made more complex logical operations possible.”

Additionally, it became practical to use living cells as factories to produce these complex proteins, allowing scientists to design custom DNA blueprints for new proteins, insert the DNA into bacteria or other host cells, and then collect the proteins with the desired structure directly from the cells.

With these new tools, DeForest and his team streamlined and improved many steps of the process at once. They designed and produced proteins with tails that spontaneously fold into more bespoke shapes, creating complex “circuits” that can respond to up to five different biomarkers. These new proteins can attach to various carriers — hydrogels, tiny beads or living cells — for delivery to a cell, or theoretically a disease site. The team even loaded up one carrier with three different proteins, each programmed to deliver their unique cargo based on different sets of environmental cues.

The research team designed protein tails that fold into custom shapes to create sophisticated logical circuits. Box 1 shows a protein designed to be responsive to five different biomarkers; box 2 shows the logical conditions that must be met to fully break apart the tail and release the protein.DeForest et al./Nature Chemical Biology

“We were so excited about the results,” DeForest said. “Using the old process, it would take months to synthesize just a few milligrams of each of these materials. Now it takes us a couple of weeks to go from construct design to product. It’s been a complete game changer for us.”

“The sky’s the limit. You can create delayed and independent delivery of many different components in one treatment,” Ross said. “And I think we could create much, much larger logical circuits that a protein can be responsive to. We’re at the point now that the technology is outpacing what we’ve seriously considered in terms of applications, which is a great place to be.”

The researchers will now continue searching for more biomarkers that proteins could target. They also hope to start collaborating with other labs at the UW and beyond to build and deploy real-world therapies.

The team outlined other uses for the technology as well. The same tools could manufacture therapies within a single cell and direct them to specific regions, a sort of microcosm of how the process works in the body. DeForest also envisions diagnostic tools like blood tests that could, say, turn a certain color when a complex set of cues within the blood sample are present.

DeForest thinks the first practical applications are likely to be cancer treatments, but with more research, the possibilities feel endless.

“The dream is to be able to pick any arbitrary location inside of the body — down to individual cells — and program a material to go and act there,” he said. “That’s a tall order, but with these technologies we’re getting closer. With the right combination of biomarkers, these materials will just get more and more precise.”

Co-authors include Annabella Li, a former UW undergraduate student of chemical engineering; Shivani Kottantharayil, a UW undergraduate student of bioengineering; and Jack Hoye, a UW doctoral student of chemical engineering.

This research was funded by the National Science Foundation and the National Institutes of Health.

For more information, contact DeForest at profcole@uw.edu. 

Evidence shows that school meals are often more nutritious than meals that students eat elsewhere. Credit: SDI Productions/iStock

In the 10 years since the federal government established the Community Eligibility Provision (CEP), which enabled universal free meal programs for schools in low-income communities, studies have suggested the policy has wide-ranging benefits. Students in participating schools choose lunches with higher nutritional quality, are suspended less frequently and may perform better academically.

Now, as cuts to food assistance programs threaten to slash access to universal school meals, a new study led by the University of Washington finds another potential benefit to the programs: Students in participating schools were less likely to have high blood pressure, suggesting that universal free meals might be a powerful tool for improving public health. 

“High blood pressure is an important public health problem that isn’t studied as much on a population level as obesity,” said Anna Localio, a UW postdoctoral researcher of health systems and population health and lead author of the study. “We have evidence that CEP increases participation in school meals, and we also have evidence that school meals are more nutritious than meals that kids obtain elsewhere. This is a public health policy that is delivering nutritious meals to children who may not have previously had access.”

For the study, published Sept. 25 in JAMA Network Open, researchers linked two datasets that rarely interact. They obtained medical records of patients ages 4-18 from community health organizations, and used patients’ addresses to identify the school they attended. The data encompassed 155,778 young people attending 1,052 schools, mostly in California and Oregon.

Researchers estimated the percentage of students with high blood pressure before and after schools opted into universal free meals, and compared those results against eligible schools that had not yet participated in the program. They also tracked students’ average systolic and diastolic blood pressure readings. All data were aggregated at the school level. 

They found that school participation in the CEP was associated with a 2.71% decrease in the proportion of students with high blood pressure, corresponding to a 10.8% net drop over five years. School participation in CEP was also associated with a decrease in students’ average diastolic blood pressure. 

Participation in universal free meals was associated with an 11% net decrease in the proportion of patients with high blood pressure over a five-year period. The above chart shows the annual difference in the percentage of students with high blood pressure in participating schools and non-participating schools.

“In previous work on the health impacts of universal free school meals, our team found that adoption of free meals is associated with decreases in average body mass index scores and childhood obesity prevalence, which are closely linked to risk of high blood pressure,” said Jessica Jones-Smith, a professor of health, society and behavior at the University of California Irvine’s Joe C. Wen School of Population & Public Health and senior author of the study. Jones-Smith conducted much of this research while on faculty at the UW School of Public Health. “So in addition to directly affecting blood pressure through provision of healthier meals, a second pathway by which providing universal free meals might impact blood pressure is through their impact on lowering risk for high BMI.” 

Improved nutrition of school meals may have helped drive the decrease, researchers said. The 2010 law that established the CEP also created stronger nutritional requirements for school meals. As a result, those meals now more closely resemble the Dietary Approaches to Stop Hypertension (DASH) diet, which studies have shown to be an effective tool for managing hypertension. 

Despite the evidence supporting the DASH diet’s effectiveness, public health officials previously lacked an effective mechanism to encourage people with high blood pressure to follow its recommendations. “We know there are a lot of barriers to people eating this diet,” Localio said, but the combination of universal free meals and increased nutritional standards likely helped students overcome those barriers.

The study also contradicts the common misperception that universal free meals mostly benefit wealthier students, because students from low-income families would already receive free meals. The study sample consists primarily of low-income patients, with 85% of included students enrolled in public health insurance such as Medicaid.

“There is a perception that providing universally free school meals will only improve outcomes for students of relatively higher-income families, but our findings suggest that there are benefits for lower-income children as well,” Jones-Smith said. “Potential mechanisms for this include decreasing the income-related stigma around eating school lunch by providing it free to all students and eliminating the time and paperwork burden of individually applying, thus decreasing barriers to participation in school meals.”

These findings come at an uncertain time for universal free meals. A school is eligible to participate in the CEP if at least 25% of its students are identified as eligible for free meals via participation in a means-tested safety net program. In this way, recent cuts to the Supplemental Nutrition Assistance Program (SNAP), the nation’s largest food assistance program, may affect schools’ access to the program.

“We’re in a contentious time for public health, but it seems like there’s bipartisan support for healthy school meals,” Localio said. “There’s legislation being considered in a number of states to expand universal free meals, and these findings could inform that decision-making. Cutting funding to school meals would not promote children’s health.” 

Co-authors on the study include Paul Hebert, research professor emeritus of health systems and population health at the UW; Melissa Knox, teaching professor of economics at the UW; Wyatt Benksen and Aileen Ochoa of OCHIN; and Jennifer Sonney, associate professor of nursing at the UW. This study was funded by the Eunice Kennedy Shriver National Institute of Child Health & Human Development. 

For more information or to contact the researchers, email Alden Woods at acwoods@uw.edu.

Over its 80-year history, the University of Washington School of Dentistry has trained nearly 7,000 dental professionals, many of whom stay in Washington. But the School’s service doesn’t start at graduation. UW dental students, faculty members and community volunteers provide free care to communities across Washington, serving hundreds of patients each academic quarter.  

The UW’s community collaborations span the state. In recent months, the School of Dentistry has offered care in Toppenish, Moses Lake and Longview, alongside monthly service days at Union Gospel Mission in Seattle and quarterly mobile clinics. Patients receive oral health exams, fillings, tooth extractions and cleanings. 

A patient receives care at a free clinic led by the UW School of Dentistry in Aberdeen, Washington.

“The work we do in communities across the state is a great example of why the UW is often called the University for Washington,” said André Ritter, dean of the UW School of Dentistry. “These programs and partnerships advance the mission of the UW and the School in significant ways through education and clinical care.” 

The clinics are organized through the School’s Office of Educational Partnerships, which is solely focused on improving the oral health of people in the Pacific Northwest. OEP coordinates outreach programs that address the distinct needs of each community. Dental students have the opportunity to serve in outreach clinics or act as mentors for middle- and high-school students, encouraging them to pursue dental education and eventually serve their own communities.  

Dental students typically begin seeing patients near the start of their third year. At the UW, however, students have the opportunity to work in clinical settings in underserved communities the summer after their first year through the Rural and Underserved Opportunities Program (RUOP).  

The School also offers a specific educational track that trains dentists to work in rural and underserved communities. Operated in conjunction with Eastern Washington University and the UW School of Medicine, the program — Regional Initiatives in Dental Education (RIDE) — has seen over 80% of its graduates return to rural and underserved communities across the Pacific Northwest. 

“Oral health is an essential part of overall well-being, and everyone deserves access to high-quality dental care,” said Amy Kim, a UW clinical associate professor of pediatric dentistry and director of the Office of Educational Partnerships. “We recognize that it is our duty and privilege to serve those who need it most.” 

 The UW School of Dentistry will continue its service and outreach programs throughout the fall and winter quarters. For more information or to learn about upcoming service days, contact Alden Woods at acwoods@uw.edu.

A worker conducts anti-mosquito fogging in Bali, Indonesia. Credit: Pepszi/Getty Images

Warmer weather across the globe is reshaping the landscape of human health. Case in point: Dengue fever incidence could rise as much as 76% by 2050 due to climate warming across a large swath of Asia and the Americas, according to a new study led by Marissa Childs, a researcher at the University of Washington. 

Dengue fever, a mosquito-borne disease once confined largely to the tropics, often brings flu-like symptoms. Without proper medical care, it can escalate to severe bleeding, organ failure, and even death.  

The study, published Sept. 9 in PNAS, is the most comprehensive estimate yet of how temperature shifts affect dengue’s spread. It provides the first direct evidence that a warming climate has already increased the disease’s toll.  

“The effects of temperature were much larger than I expected,” said Childs, a UW assistant professor of environmental and occupational health sciences who conducted much of the research as a doctoral student at Stanford University. “Even small shifts in temperature can have a big impact for dengue transmission, and we’re already seeing the fingerprint of climate warming.” 

The study analyzed over 1.4 million observations of local dengue incidence across 21 countries in Central and South America and Southeast and South Asia, capturing both epidemic spikes and background levels of infection.  

Dengue thrives in a “Goldilocks zone” of temperatures — incidence peaks at about 27.8 degrees Celsius, or 82 degrees Fahrenheit, rising sharply as cooler regions warm but dropping slightly when already-hot areas exceed the optimal range. As a result, some of the largest increases are projected for cooler, high-population regions in countries such as Mexico, Peru and Brazil. Many other endemic regions will continue to experience larger, warming-fueled dengue burdens. By contrast, a few of the hottest lowland areas may see slight declines.  

Still, the net global effect is a steep rise in disease. 

The findings suggest that higher temperatures from climate change were responsible for an average 18% increase of dengue incidence across 21 countries in Asia and the Americas from 1995 to 2014 — translating to more than 4.6 million extra infections annually, based on current incidence estimates. Cases could climb another 49% to 76% by 2050 depending on greenhouse gas emissions levels, according to the study. At the higher end of the projections, incidence of dengue would more than double in many cooler locations, including areas in the study countries that are already home to over 260 million people.  

“Many studies have linked temperature and dengue transmission,” said senior author Erin Mordecai, a professor of biology in the Stanford School of Humanities and Sciences. “What’s unique about this work is that we are able to separate warming from all the other factors that influence dengue — mobility, land use change, population dynamics — to estimate its effect on the real-world dengue burden. This is not just hypothetical future change but a large amount of human suffering that has already happened because of warming-driven dengue transmission.” 

The researchers cautioned that their estimates are likely conservative. They do not account for regions where dengue transmission is sporadic or poorly reported, nor do they include large endemic areas such as India or Africa where detailed data is lacking or not publicly available. The researchers also highlighted recent locally acquired cases in California, Texas, Hawaii, Florida, and in Europe — a signal of the expanding range of dengue. Urbanization, human migration and the evolution of the virus could amplify risks, while medical advances may help blunt them, making projections uncertain. 

Aggressive climate mitigation would significantly reduce the dengue disease burden, according to the study. At the same time, adaptation will be essential. This includes better mosquito control, stronger health systems and potential widespread use of new dengue vaccines. 

In the meantime, the findings could help guide public health planning and strengthen efforts to hold governments and fossil fuel companies accountable for climate change damages. Attribution studies are increasingly entering courtrooms and policy debates, used to assign responsibility for climate damages and to support funds compensating countries most affected.  

“Climate change is not just affecting the weather — it has cascading consequences for human health, including fueling disease transmission by mosquitoes,” Mordecai said. “Even as the U.S. federal government moves away from investing in climate mitigation and climate and health research, this work is more crucial than ever for anticipating and mitigating the human suffering caused by fossil fuel emissions.” 

Co-authors of the study include Kelsey Lyberger of Arizona State University, Mallory Harris of the University of Maryland, and Marshall Burke of Stanford. Lyberger and Harris completed much of their work while at Stanford.   

The research was funded by the Illich-Sadowsky Fellowship through the Interdisciplinary Graduate Fellowship program at Stanford University; an Environmental Fellowship at the Harvard University Center for the Environment; the National Institutes of Health; the National Science Foundation (with the Fogarty International Center); the Stanford Center for Innovation in Global Health; the Stanford King Center on Global Development; and the Stanford Woods Institute for the Environment. 

Adapted from a press release by Stanford University. For more information or to contact the researchers, email Alden Woods at acwoods@uw.edu.

• Earlier blood transfusion after major surgery – when hemoglobin was below 10 g/dL rather than beow 7 g/dl - did not affect the risk of severe complications, such as death, heart attack, need for a heart procedure, kidney failure or stroke.
• However, the timing of the blood transfusion may be associated with a lower risk of irregular heartbeat and heart failure among people with heart disease, according to a new study of U.S. military veterans.
• Note: This trial is simultaneously published today as a full manuscript in the peer-reviewed scientific journal JAMA.

Embargoed until 3:57 p.m. CT/4:57 p.m. ET, Saturday, Nov. 8, 2025

NEW ORLEANS, Nov. 8, 2025 — An earlier blood transfusion- done when hemoglobin levels were higher - after major general or vascular surgery among people with heart disease was associated with a lower risk of some complications but not the most severe ones, 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 Transfusion Trigger after Operations in High Cardiac Risk Patients (TOP) trial investigated whether transfusing blood earlier, when hemoglobin levels drop below 10 g/dL after major surgery, may prevent complications among heart patients better than a strategy that calls for transfusions when hemoglobin levels drop below 7 g/dL. Hemoglobin is a vital component of red blood cells that transports oxygen throughout the body. 

In this study of more than 1,400 military veterans having major general or vascular surgery, hemoglobin levels were assessed after surgery and reassessed after each transfusion to determine if additional transfusions were warranted until discharge or 30 days, whichever came first.

The trial compared the combined frequency of major complications, such as death, heart attack, kidney failure, need for a heart procedure or stroke to less severe but still serious complications like pneumonia, sepsis, wound infections, new irregular heartbeat, cardiac arrest or heart failure, for the two strategies 90 days after surgery.

“When excessive blood loss or anemia occurs during or after surgery, a blood transfusion may be needed. For people with heart disease, the risk of complications due to the strain of blood loss means that the timing of a blood transfusion is critical,” explained lead author Panos Kougias, M.D., M.Sc., chair of the department of surgery at SUNY Downstate Health Sciences University in Brooklyn, New York. “The current standard of care for most patients is to wait until hemoglobin levels are low before transfusing blood.”

“Our findings suggest that persistent blood loss in patients with serious underlying heart issues does not increase the risk of serious complications, such as death, heart attack, kidney failure, need for a heart procedure or stroke. However, it might place a greater strain on the heart than the volume from a transfusion, leading to problems like heart failure and irregular heartbeat,” Kougias said. “The earlier blood transfusion strategy may protect the heart from the effects of blood loss. It’s like keeping a car’s fuel tank above half full, while the transfusion-later strategy is like adding fuel only when the low-fuel light comes on.”

The analysis found:

• Severe complication rates — death, heart attack, kidney failure, need for a heart procedure or stroke — were similar among patients who received earlier or later blood transfusion: 9.1% in the early (liberal) transfusion group vs. 10.1% in the later (restrictive) transfusion group.
• Irregular heart rhythms and heart failure occurred in 5.9% of patients in the early (liberal) transfusion group compared to 9.9% in the later (restrictive) transfusion group, representing a substantial 41% lower risk among the early transfusion group.

“We were surprised that the restrictive transfusion strategy — giving less blood by only transfusing once patients’ hemoglobin levels were below 7 g/dL — was associated with a higher rate of heart failure,” Kougias said. “The traditional thinking has been that giving more blood may potentially overload the heart and worsen failure. Our finding suggests that in high-risk heart patients, persistent anemia might place a greater strain on the heart than the volume from a transfusion, leading to complications such as heart failure and arrhythmia. As this was a secondary outcome in our study, further research will be needed to confirm this finding.

“These results suggest that a one-size-fits-all transfusion strategy may not be best,” he said. “For some patients, waiting to transfuse remains safe and appropriate. However, for patients with serious underlying heart disease undergoing major surgery, our findings show that an earlier blood transfusion could help prevent serious heart complications, other than a heart attack.”

The study’s limitations include that most participants were men, so the results may not apply to women. In addition, health care professionals knew which patients received which transfusion strategy, which may have affected patient care. In addition, the number of severe complications was fewer than expected, which means that small differences may have gone undetected.

Study details, background and design:

• The TOP trial included 1,424 U.S. military veterans receiving care at 16 Veterans Affairs Medical Centers throughout the U.S., enrolled in the study between February 2018 to March 2023.
• Participants’ average age was 70 years old; 98% were men; and 75% self-reported they were white adults, 19% were Black adults and 4% were Hispanic or Latino adults.
• The criteria for the different transfusion strategies were hemoglobin below 10 g/dL for the early or liberal approach, and hemoglobin below 7 g/dL for the later or restrictive transfusion approach.
• Researchers measured hemoglobin levels after surgery and after each transfusion.
• Participants were followed for 90 days after surgery.

Co-authors and disclosures are listed in the abstract. This trial was funded by the Veterans Affairs Office of Research and Development. 

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.

The Association receives more than 85% of its revenue from sources other than corporations. These sources include contributions from individuals, foundations and estates, as well as investment earnings and revenue from the sale of our educational materials. Corporations (including pharmaceutical, device manufacturers and other companies) also make donations to the Association. The Association has strict policies to prevent any donations from influencing its science content and policy positions. Overall financial information is available here.

   Additional Resources:

• Multimedia is available on the right column of the release link.
• Link to abstract; and the American Heart Association’s Scientific Sessions 2025 Online Program Planner
• American Heart Association news release: Red blood cell transfusions may improve outcomes in heart attack patients with anemia (Nov. 2023)  
• About Scientific Sessions 2025
• For more news at the American Heart Association’s Scientific Sessions 2025, follow us on X @HeartNews, #AHA25

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About the American Heart Association

The American Heart Association is a relentless force for a world of longer, healthier lives. Dedicated to ensuring equitable health in all communities, the organization has been a leading source of health information for more than one hundred years. Supported by more than 35 million volunteers globally, we fund groundbreaking research, advocate for the public’s health, and provide critical resources to save and improve lives affected by cardiovascular disease and stroke. By driving breakthroughs and implementing proven solutions in science, policy, and care, we work tirelessly to advance health and transform lives every day. Connect with us on heart.org, Facebook, X or by calling 1-800-AHA-USA1.

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• Successful catheter ablation resulted in a low risk of stroke associated with atrial fibrillation (AFib), a type of irregular heart rhythm, according to an international study.
• Researchers said these findings may suggest that ongoing blood-thinning medication may not be needed after an ablation procedure.
• While catheter ablation is known to reduce the occurrence of AFib, it’s been unclear if it also reduces the increased stroke risk associated with the AFib.
•  Note: This trial is simultaneously published today as a full manuscript in the peer-reviewed scientific journal New England Journal of Medicine.

Embargoed until 2:15 p.m. CT/ 3:15 p.m. ET, Saturday, Nov. 8, 2025

NEW ORLEANS, Nov. 8, 2025 — A minimally invasive heart procedure to correct irregular heart rhythms called catheter ablation may reduce the risk of stroke enough that some patients can discontinue blood thinners, 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.

In the OCEAN Randomized Trial, researchers evaluated whether long-term oral anticoagulation is needed after successful ablation in people with an increased risk of stroke. An international group of researchers enrolled nearly 1,300 adults at multiple sites in several countries and followed their progress for three years after they had ablation to treat atrial fibrillation (AFib). Participants included people with no evidence of irregular heart rhythm recurrence and those with moderate to high stroke risk, which calls for long-term blood thinners.

According to the American Heart Association, AFib increases stroke risk by five-fold and can lead to blood clots, heart failure and death. 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.

The condition can be treated with catheter ablation, a minimally invasive nonsurgical procedure that can eliminate the electrical triggers for AFib and prevent the irregular rhythms from returning. Current American Heart Association/American College of Cardiology  guidelines recommend continuing blood-thinning medications in moderate-to-high risk individuals to prevent stroke, even after a successful ablation.

“We know that ablation for AFib is effective, however, we did not know if elimination of the arrhythmia also reduces the long-term risk of stroke,” said study author Atul Verma, M.D., director of cardiology at McGill University Health Centre in Montreal. “Many people who have undergone successful ablation will ask ‘Can I stop my blood thinners?’ Until now, we have told them to continue taking blood thinners because we had insufficient evidence to suggest it was safe to stop. So, it was important to find out if successful ablation could allow discontinuing blood thinners.”

Researchers prescribed half of the eligible participants 75-160 mg of aspirin (a mild antiplatelet) daily. The other half were prescribed 15 mg daily of oral rivaroxaban, a potent blood thinner.

The study found that prescribing the blood thinner rivaroxaban after catheter ablation to treat AFib offered no major difference in stroke protection than those taking aspirin and increased bleeding risk compared to aspirin. Specifically:

• The three-year risk of stroke, including a covert stroke, which is only detectable on brain imaging, was 0.8% in the rivaroxaban group and 1.4% in the aspirin group.
• The annual stroke risk was 0.3% in the rivaroxaban arm and 0.7% in the aspirin arm —variances not significant enough to indicate a notable difference between groups.
• There were no notable differences in major or fatal bleeding complications whether people took rivaroxaban or aspirin.
• However, clinically relevant, non-major bleeding (bleeding serious enough to cause people to seek medical attention) was 5.5% for rivaroxaban versus 1.6% for aspirin, or about 3.5 times more likely with rivaroxaban.

“In essence, catheter ablation for AFib reduced the recurrence of atrial fibrillation and can also reduce the risk of stroke associated with this common heart rhythm condition,” Verma said. “With the notably increased bleeding risk associated with rivaroxaban, we concluded that the anticoagulant did not offer any advantages in comparison to aspirin for reducing what we found to be a low stroke risk in these individuals. Now, we can advise patients that it may be safe to stop blood thinners, even if they have a moderate stroke risk.”

Study details, background and design:

• The study included 1,284 adults, average age 66 years, 71% men, who on average were within 16.4 months of their last ablation procedure.
• Participants were enrolled in health care centers in Canada, Australia, Germany, Belgium, Israel and China between March 30, 2016, and July 25, 2022, and their progress was followed for three years.
• Researchers used the CHA₂DS₂-VASc score, which measures a person with AFib’s risk of stroke on a scale of 0 to 9 based on the presence of other conditions, such as heart failure, hypertension, diabetes, prior stroke or vascular disease, plus their age and sex. In this study, the average CHA₂DS₂-VASc score at enrollment was 2.2, and nearly 32% of participants had a score of 3 or higher, which is considered high risk.
• Researchers collected data on stroke, systemic embolism and bleeding events, and all participants had  brain magnetic resonance imaging (MRI) at enrollment and again at three years.
• Participants were randomly assigned to one of two groups for the duration of the trial:   aspirin 75-160 mg daily or rivaroxaban 15 mg daily.
• Data was analyzed between the two groups: rivaroxaban (anticoagulation) vs. aspirin (antiplatelet).

Among the study’s limitations, only a small percentage of participants a CHA₂DS₂-VASc score of 4 or higher. As a result, the findings may not be relevant to higher-risk individuals.

Co-authors, funding information and disclosures 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.

The Association receives more than 85% of its revenue from sources other than corporations. These sources include contributions from individuals, foundations and estates, as well as investment earnings and revenue from the sale of our educational materials. Corporations (including pharmaceutical, device manufacturers and other companies) also make donations to the Association. The Association has strict policies to prevent any donations from influencing its science content and policy positions. Overall financial information is available here.

Additional Resources:

• Multimedia is available on the right column of the release link.
• View the abstract in the American Heart Association Scientific Sessions 2025 Online Program Planner
• American Heart Association news release: New research finds 62% of AFib patients were unaware of the condition before diagnosis (Sept. 2025)
• American Heart Association health information: Fact Sheet: What Is Atrial Fibrillation?
• American Heart Association health initiative: My AFib Experience®
• About Scientific Sessions 2025  
• For more news at AHA Scientific Sessions 2025, follow us on X @HeartNews,#AHA25

###

About the American Heart Association

The American Heart Association is a relentless force for a world of longer, healthier lives. Dedicated to ensuring equitable health in all communities, the organization has been a leading source of health information for more than one hundred years. Supported by more than 35 million volunteers globally, we fund groundbreaking research, advocate for the public’s health, and provide critical resources to save and improve lives affected by cardiovascular disease and stroke. By driving breakthroughs and implementing proven solutions in science, policy, and care, we work tirelessly to advance health and transform lives every day. Connect with us on heart.org, Facebook, X or by calling 1-800-AHA-USA1.

For Media Inquiries and American Heart Association Expert Perspective:

American Heart Association Communications & Media Relations in Dallas: 214-706-1173;ahacommunications@heart.org

Bridgette McNeill: bridgette.mcneill@heart.org

For Public Inquiries: 1-800-AHA-USA1 (242-8721)

heart.org and stroke.org

• 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.

Embargoed until 2 p.m. C.T./3 p.m. ET, Saturday, Nov. 8, 2025

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.

The Association receives more than 85% of its revenue from sources other than corporations. These sources include contributions from individuals, foundations and estates, as well as investment earnings and revenue from the sale of our educational materials. Corporations (including pharmaceutical, device manufacturers and other companies) also make donations to the Association. The Association has strict policies to prevent any donations from influencing its science content and policy positions. Overall financial information is available here.

Additional Resources:

• Multimedia is available on the right column of the release link.
• Link to abstract; and the American Heart Association’s Scientific Sessions 2025 Online Program Planner
• American Heart Association news release: New research finds 62% of AFib patients were unaware of the condition before diagnosis (Sept. 2025)
• American Heart Association news release: Regular dental flossing may lower risk of stroke from blood clots, irregular heartbeats | American Heart Association (Jan. 2025)
• American Heart Association news release: Early Rhythm Control, Lifestyle Modification and More Tailored Stroke Risk Assessment Are Top Goals in Managing Atrial Fibrillation (Nov. 2023)
• American Heart Association Guideline: 2023 ACC/AHA/ACCP/HRS Guideline for the Diagnosis and Management of Atrial Fibrillation: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines
• American Heart Association health information: FAQ About AFib
• American Heart Association health information: Join an online peer group and community for people living with atrial fibrillation
• About Scientific Sessions 2025
• For more news at the American Heart Association’s Scientific Sessions 2025, follow us on X @HeartNews,#AHA25

###

About the American Heart Association

The American Heart Association is a relentless force for a world of longer, healthier lives. Dedicated to ensuring equitable health in all communities, the organization has been a leading source of health information for more than one hundred years. Supported by more than 35 million volunteers globally, we fund groundbreaking research, advocate for the public’s health, and provide critical resources to save and improve lives affected by cardiovascular disease and stroke. By driving breakthroughs and implementing proven solutions in science, policy, and care, we work tirelessly to advance health and transform lives every day. Connect with us on heart.org, Facebook, X or by calling 1-800-AHA-USA1.

For Media Inquiries and American Heart Association Expert Perspective: 214-706-1173

American Heart Association Communications & Media Relations in Dallas: ahacommunications@heart.org

Bridgette McNeill: bridgette.mcneill@heart.org

For Public Inquiries: 1-800-AHA-USA1 (242-8721)

heart.org and stroke.org

• A one-month course of dual clot-preventing therapy followed by a single clot-prevention medication for the remainder of the standard 12-month regimen in adults with atrial fibrillation (AFib) who received a coronary stent was as effective as one year of continuous dual therapy for preventing stroke, heart attack and death.
• Participants treated with the one-month regimen experienced fewer bleeding problems than those in the year-long dual-treatment group.
• This is the first study to suggest the one-month strategy is as safe and effective as the standard year-long regimen of dual clot-preventing therapy for people with AFib treated with a stent.
• 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.

Embargoed until 1:45 p.m., CT/2:45 p.m. ET, Saturday, Nov. 8, 2025

NEW ORLEANS, Nov. 8, 2025 — New research found a simplified clot-preventing medication regimen following stent placement in adults with atrial fibrillation was just as safe and effective in preventing strokes, heart attack and death, when compared to a standard year-long treatment regimen, 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.

This study included adults with atrial fibrillation (AFib), a common heart rhythm disorder, who received a stent in a heart artery to improve blood flow. Standard treatment after a stent implantation is a prescription for two clot-preventing medications for one year, however, these medications can also increase the risk of serious bleeding, explained study author Yohei Sotomi, M.D., Ph.D., director of the Osaka Cardiovascular Conference Multicenter Clinical Research Lab in the Department of Cardiovascular Medicine at University of Osaka Graduate School of Medicine in Osaka, Japan. The two medications included a direct oral anticoagulant, such as dabigatran, rivaroxaban, apixaban and edoxaban to help prevent strokes; and a P2Y12 inhibitor, such as clopidogrel or prasugrel, to prevent clots in the stent.

In this study, the OPTIMA-AF trial, researchers explored if using both medications for one month among people with AFib who received a stent would be equally safe and effective as 12 months of treatment, while helping to reduce bleeding risk associated with the medications.

“Previous studies confirmed that using two anti-clotting agents instead of three reduced bleeding, however, no study has tested whether the duration of dual therapy could be safely shortened to just one month,” Sotomi said. “Our study is the first to show that a one-month strategy is both safe and effective, offering real-world benefits for patients and doctors.”

Researchers studied more than 1,000 adults in Japan who had AFib and received a stent in a heart artery. After the stent placement procedure, half of the study participants were prescribed both types of medications for one month, then only the direct oral anticoagulant for the remaining 11 months. The other half of participants continued dual therapy for 12 months.

Participants were followed for one year to monitor if they had a stroke, heart attack or died. Researchers also analyzed how many participants had bleeding complications such as gastrointestinal bleeding.

The analysis found:

• 5.4% of participants in the one-month group and 4.5% in the 12-month group had a heart attack, stroke or died, which researchers said suggests the shorter approach was equally effective.
• Participants in the one-month dual-treatment group had notably fewer bleeding complications: 4.8% versus 9.5% in the 12-month group.
• Most of the bleeding reduction came from less serious bleeds that required medical attention, which affects quality of life and can increase health care costs for emergency or clinic visits, lab and imaging tests.

“These results may help doctors feel more confident in prescribing shorter durations of dual antithrombotic therapy after stenting among some patients with AFib,” Sotomi said. “By reducing the length of time individuals are exposed to combination therapy, we can lower the risk of bleeding — a serious concern for many older adults—without increasing their risk of stroke or heart attack.”

Up to one in 10 people who receive a stent also have AFib, a disorder that increases stroke risk by five-fold and can lead to blood clots, heart failure and death, Sotomi said. According to the American Heart Association 2025 Heart and Stroke statistics, an estimated five million adults in the U.S. have AFib, and it is predicted that more than 12 million people in the U.S. will have it by 2030.

The study was conducted in Japan, so its findings may not directly apply to people in other countries. Another limitation is that study participants mostly had stable heart disease, so results may not apply to patients with higher risk for blood clots. In addition, only about 20% of the study population were women, so generalizability to women is limited.

Study details, background and design:

• The study included 1,101 adults with an average age of 75.2 years old; 79% were men; and all had atrial fibrillation and underwent a procedure to implant a drug-eluting stent.
• The study enrolled participants with AFib who received stents at 75 hospitals in Japan between October 2019 and September 2024.
• Researchers collected data on rates of death, stroke, heart attack, clotting in stents and bleeding events.
• The trial compared one-month versus 12-month dual antithrombotic therapy with a direct oral anticoagulant and a P2Y12 inhibitor, followed by the oral anticoagulant alone, with outcomes assessed at 12 months.
• Participants and researchers knew which regimen each participant received; however, assignment to the regimens was by chance.

Co-authors, their disclosures and funding information is 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.

The Association receives more than 85% of its revenue from sources other than corporations. These sources include contributions from individuals, foundations and estates, as well as investment earnings and revenue from the sale of our educational materials. Corporations (including pharmaceutical, device manufacturers and other companies) also make donations to the Association. The Association has strict policies to prevent any donations from influencing its science content and policy positions. Overall financial information is available here.

Additional Resources:

• Multimedia is available on the right column of the release link.
• View the abstract in the American Heart Association Scientific Sessions 2025 Online Program Planner
• American Heart Association health information: Learn about AFib and your heart (Video)
• Watch an animation of atrial fibrillation. 
• American Heart Association health information: What Is a Coronary Artery Stent?
• American Heart Association patient support network: MyAFibExperience® 
• American Heart Association guidelines: 2023 ACC/AHA/ACCP/HRS Guideline for the Diagnosis and Management of Atrial Fibrillation: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines
• About Scientific Sessions 2025
• For more news at AHA Scientific Sessions 2025, follow us on X @HeartNews,#AHA25

###

About the American Heart Association

The American Heart Association is a relentless force for a world of longer, healthier lives. Dedicated to ensuring equitable health in all communities, the organization has been a leading source of health information for more than one hundred years. Supported by more than 35 million volunteers globally, we fund groundbreaking research, advocate for the public’s health, and provide critical resources to save and improve lives affected by cardiovascular disease and stroke. By driving breakthroughs and implementing proven solutions in science, policy, and care, we work tirelessly to advance health and transform lives every day. Connect with us on heart.org, Facebook, X or by calling 1-800-AHA-USA1.

For Media Inquiries and American Heart Association Expert Perspective:

American Heart Association Communications & Media Relations in Dallas: 214-706-1173;ahacommunications@heart.org

Bridgette McNeill: bridgette.mcneill@heart.org

For Public Inquiries: 1-800-AHA-USA1 (242-8721)

heart.org and stroke.org

• For people who have experienced a heart attack or stroke, or who are at high risk of one and need further cholesterol lowering, a new daily pill may be a more convenient yet similarly effective option to injectable therapies.
• The oral medication, enlicitide, lowered LDL cholesterol by up to 60% and could eventually offer an option for people whose LDL levels remain above goal despite lifestyle changes and standard cholesterol medications like statins.
• A longer, ongoing cardiovascular outcomes study will examine whether enlicitide can reduce the risk of heart attack or stroke.
• Note: The study featured in this news release is a research abstract. Abstracts presented at the 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.

Embargoed until 1:30 p.m. CT/2:30 p.m. ET, Saturday, Nov. 8, 2025

This news release contains updated information from the research authors that was not in the abstract.

NEW ORLEANS, Nov. 8, 2025 — Among people with a previous heart attack or stroke, or who are at high risk for one, a daily oral medication may offer an effective alternative to injections of PCSK9 inhibitors to lower low-density lipoprotein (LDL or “bad” cholesterol), 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.

“This oral medication is set to be another powerful addition to the treatments we currently have to lower LDL cholesterol and hopefully prevent cardiovascular events,” said lead study author Ann Marie Navar, M.D., Ph.D., FAHA, an associate professor of cardiology at the University of Texas Southwestern Medical Center in Dallas. “Many patients struggle to reach guideline-recommended cholesterol targets despite currently available therapies, leaving them at unnecessary risk of stroke and/or heart attack.”

In the last decade, a new FDA-approved type of medication became available to reduce bad cholesterol in people who don’t achieve recommended levels despite lifestyle changes and maximum treatment with statin medications. Known as PCSK9 inhibitors, these medications include antibodies that block the PCSK9 protein from binding to the LDL receptor, and small interfering RNA, which reduce the production of the PCSK9 protein. Inhibiting PCSK9 helps increase the number of LDL receptors available to help clear “bad” cholesterol out of the bloodstream. Both classes of PCSK9 inhibitors are only administered by injection under the skin.

In 2021, studies found that an investigational, oral small molecule macrocyclic peptide, enlicitide, can also block PCSK9 from binding to LDL receptors, thereby reducing blood levels of LDL when taken daily. This study, Efficacy and Safety of Enlicitide, an Oral PCSK9 Inhibitor, for Lowering LDL Cholesterol in Adults with or At-Risk for ASCVD: The Phase 3 CORALreef Lipids Trial (CORALreef Lipids), is a phase 3 trial in adults evaluating the safety and LDL-lowering ability of enlicitide.

After 24 weeks of daily treatment, the analysis found that compared with those taking a placebo, participants taking enlicitide had:

• up to a 60% reduction in LDL cholesterol, with sustained reductions at 52 weeks;
• a 53% reduction in non-HDL, a combination of all types of cholesterol except for HDL (“good cholesterol”);
• a 50% reduction in ApoB, a protein that helps carry fat and various “bad” types of cholesterol throughout the body;
• a 28% reduction in Lp(a), a different type of lipoprotein that is structurally similar to LDL, determined by genetics and a risk factor for heart disease; and
• a similar rate of serious side effects (10% in enlicitide vs. 12% in placebo), a small proportion of participants left the study early because of side effects (3% vs.4%, respectively).

In this study, 7 out of 10 participants taking enlicitide had at least a 50% reduction in LDL-C and also achieved an LDL below 70 mg/dL, and more than two-thirds reduced their LDL-C by at least 50% or more and also achieved levels below 55 mg/dL.

“In addition to these dramatic improvements when compared with placebo, daily enlicitide resulted in almost identical changes in LDL, non-HDL and ApoB to those achieved with the injectable antibodies alirocumab and evolocumab,” Navar said. “And, results with enlicitide were numerically better than what has been shown for the siRNA medication inclisiran, which blocks the production of the PCSK9 protein.”

Study details, background or design:

• The study enrolled 2,912 adults (average age of 63 years; 39% were women) with a previous heart attack or stroke or assessed to be at intermediate or high risk of a heart attack or stroke within the next 10 years.
• All participants had LDL levels above recommended levels despite being on a stable course of lipid-lowering therapy for 30 days or more, including treatment with least moderate or high-intensity statin therapy (or with a history of intolerance to statins).
• At the start of the study, 97% of participants were taking statins, and 26% were also taking a medication that reduces the absorption of cholesterol in the small intestines such as ezetimibe.
• Participants were randomized in a 2-to-1 ratio to receive either 20 mg enlicitide once daily (n=1,935) or placebo (n=969). Five participants never received the study medication, and three were excluded for being enrolled in multiple trials across multiple sites.
• The study data was collected between August 2023 and July 2025 at 168 health care centers in 14 countries.

“The CORALreef outcomes trial is still ongoing and will determine if and by how much the lower LDLs achieved with enlicitide will prevent major cardiovascular events,” Navar said.

Co-authors, their disclosures and funding information 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.

The Association receives more than 85% of its revenue from sources other than corporations. These sources include contributions from individuals, foundations and estates, as well as investment earnings and revenue from the sale of our educational materials. Corporations (including pharmaceutical, device manufacturers and other companies) also make donations to the Association. The Association has strict policies to prevent any donations from influencing its science content and policy positions. Overall financial information is available here.

Additional Resources:

• Multimedia is available on the right column of the release link.
• View the abstract in the American Heart Association Scientific Sessions 2025 Online Program Planner
• American Heart Association news release: In a small international trial, novel oral medication muvalaplin lowered Lp(a) (Nov. 2024)
• American Heart Association news release: New research project aims to set a standardized approach to lipoprotein(a) management (March 2023)
• American Heart Association health information: Lipoprotein (a) Meaning and How Does it Impact My Heart Health?
• About Scientific Sessions 2025  
• For more news at the American Heart Association’s Scientific Sessions 2025, follow us on X @HeartNews,#AHA25

###

About the American Heart Association

The American Heart Association is a relentless force for a world of longer, healthier lives. Dedicated to ensuring equitable health in all communities, the organization has been a leading source of health information for more than one hundred years. Supported by more than 35 million volunteers globally, we fund groundbreaking research, advocate for the public’s health, and provide critical resources to save and improve lives affected by cardiovascular disease and stroke. By driving breakthroughs and implementing proven solutions in science, policy, and care, we work tirelessly to advance health and transform lives every day. Connect with us on heart.org, Facebook, X or by calling 1-800-AHA-USA1.

For Media Inquiries and American Heart Association Expert Perspective:

American Heart Association Communications & Media Relations in Dallas: 214-706-1173;ahacommunications@heart.org

Karen Astle: Karen.Astle@heart.org

For Public Inquiries: 1-800-AHA-USA1 (242-8721)

heart.org and stroke.org