Research reviewed by Gram suggests that switching from warfarin to rivaroxaban may slow the buildup of artery plaque and reduce calcification in mice. In a 2026 study, mice that moved from warfarin to rivaroxaban after six weeks had less artery calcification than mice kept on warfarin. These findings come from animal research and have not yet been tested in people.
Gram Research analysis of a 2026 study in TH Open looked at whether changing blood thinners could protect arteries. Warfarin is an older blood thinner that some researchers worry may encourage calcium to build up in blood vessels. Rivaroxaban is a newer option. Scientists fed mice bred to develop clogged arteries a high-fat, Western-style diet for 18 weeks. Some mice took no extra medicine, some took warfarin, some took rivaroxaban, and one group took warfarin for six weeks before switching to rivaroxaban for 12 weeks. Mice on rivaroxaban had less calcium in their arteries. The switching group had smaller plaques, less stiff blood vessels, and more stable plaques. Only rivaroxaban lowered a protein linked to plaque breakdown. Because this study was done in mice, the results cannot yet be applied directly to people.
Key Statistics
A 2026 mouse study published in TH Open found that mice switched from warfarin to rivaroxaban had a greater reduction in artery calcification than mice that stayed on warfarin for the full 18 weeks.
In that 18-week study, mice fed a Western-style diet and given rivaroxaban, either throughout or after six weeks of warfarin, developed smaller artery plaques than mice that took warfarin alone.
The 2026 mouse study found that only rivaroxaban reduced levels of MMP-9, an enzyme that can break down artery plaque, while all three blood thinner groups showed lower oxidative stress and PAR2 levels.
The Quick Take
- What they studied: Researchers wanted to know whether switching from warfarin, an older blood thinner, to rivaroxaban, a newer one, could reduce artery plaque and calcium buildup better than staying on warfarin.
- Who participated: The study used laboratory mice that were genetically altered to develop clogged arteries more easily. The exact number of mice was not stated in the summary provided. Humans did not take part.
- Key finding: Mice that switched from warfarin to rivaroxaban had a larger drop in artery calcium than mice that stayed on warfarin. Mice on rivaroxaban, whether they switched or took it from the start, also had smaller artery plaques than mice on warfarin for the full 18 weeks.
- What it means for you: This research is early and comes from animal studies, so it does not prove that switching blood thinners protects human arteries. Anyone taking warfarin should talk with their doctor before making any change, since stopping or switching medicine on your own can be dangerous.
The Research Details
The researchers used mice that lack a protein called apolipoprotein E, a protein that helps clear fats from the blood. These mice tend to develop plaque buildup in their arteries, which makes them a common model for studying heart disease. All the mice ate a Western-style diet, which is high in fat and sugar, for 18 weeks.
The mice were divided into groups. One group received no extra medicine. Another received warfarin for the full 18 weeks. A third received rivaroxaban for the full 18 weeks. A fourth group took warfarin for the first six weeks and then switched to rivaroxaban for the final 12 weeks. This last group allowed the team to test what happens when a patient changes medicines partway through treatment.
At the end of the study, the researchers examined the arteries under a microscope and tested their stiffness. They also measured calcium deposits, collagen (a structural protein that helps keep plaques stable), and levels of several proteins and markers linked to inflammation, oxidative stress, and plaque breakdown.
Using a controlled animal model lets researchers compare groups under the same diet and conditions. This makes it easier to see whether the medicine itself, rather than other factors, is linked to changes in the arteries. Including a switching group also reflects a real-world question, since many patients change blood thinners over time.
The study used clear comparison groups and measured several different signs of artery health, which strengthens confidence in the pattern of results. However, the summary does not give the number of mice per group, and the study was done in animals. Animal findings often do not carry over to people, and this study was published in a smaller journal that has not yet been widely evaluated for impact.
What the Results Show
Plaque size was similar in mice that took rivaroxaban the whole time and mice that switched from warfarin to rivaroxaban. Both groups had smaller plaques than mice on warfarin or no medicine after 18 weeks. This suggests that rivaroxaban may help limit how large artery plaques grow in this model.
Calcification, the hardening that occurs when calcium builds up in artery walls, dropped in both rivaroxaban groups. The biggest reduction appeared in the switching group compared with mice kept on warfarin. This is notable because warfarin has been linked in earlier research to calcium buildup in blood vessels, and the switch appeared to reverse some of that damage.
The switching group also showed better vessel health. Their arteries were less stiff, and they had fewer breaks in the elastic fibers that help blood vessels stretch and recoil. Their plaques also looked more stable, with more smooth muscle cells and more collagen. Stable plaques are generally less likely to rupture and cause a heart attack or stroke.
All three blood thinner groups showed lower levels of a protein called PAR2 and less oxidative stress, a type of cell damage caused by unstable molecules. Only the rivaroxaban groups showed reduced levels of MMP-9, an enzyme that can break down the structure of plaques.
The reduction in PAR2 and oxidative stress across all three blood thinner groups suggests that these medicines may affect inflammation and cell damage in plaques. Because warfarin also lowered these markers, the difference between the medicines seems to lie mainly in calcification, plaque stability, and MMP-9 levels. These results point to rivaroxaban offering broader protection for artery walls than warfarin in this model.
Warfarin has long been a standard blood thinner, and earlier research has raised concerns that it may interfere with vitamin K pathways that help keep calcium out of blood vessels. Newer blood thinners such as rivaroxaban do not depend on vitamin K in the same way. This study adds to growing interest in whether those newer medicines may protect arteries as well as prevent clots, although more research in people is needed to confirm this.
The most important limitation is that the study used mice, not people. Mouse biology differs from human biology in many ways, so the results may not match what happens in patients. The summary also does not state how many mice were in each group, which makes it harder to judge how strong the results are. Mice were fed a specific high-fat diet, so the findings may not apply to people with different diets or health conditions. Finally, the study shows associations and effects in a lab setting, not proof of long-term benefits for human heart health.
The Bottom Line
Based on this mouse study alone, the evidence is early and preliminary. It suggests that rivaroxaban may reduce artery calcification and plaque instability more than warfarin in this model, but these results should be treated as a reason for further research, not a reason to change medicine. Confidence in applying these findings to people is currently low. Any decision about switching blood thinners should be made with a doctor who knows your full health history.
People taking warfarin, doctors who prescribe blood thinners, and researchers studying heart disease and artery health may find this research especially relevant. People who are not taking any blood thinner or who have no heart or circulation conditions should not change their medicine based on this study. Anyone currently taking warfarin should keep taking it as prescribed until a healthcare provider advises otherwise.
Because this research was done in mice over 18 weeks, it is not possible to say how long any benefits would take in people. Human studies would need to track artery calcification and plaque changes over months or years. Anyone considering a change in medicine should expect a doctor to review blood test results, imaging, and overall risk before any decision is made, and it may take many months to see meaningful changes in artery health.
Frequently Asked Questions
Does switching from warfarin to rivaroxaban reduce artery calcification?
In a 2026 mouse study, rivaroxaban lowered artery calcification in both treatment groups. The switching group, which moved from warfarin to rivaroxaban, showed a larger reduction than mice that stayed on warfarin. Results come from animal research and have not been confirmed in human patients.
Is rivaroxaban better than warfarin for protecting arteries?
Early animal research suggests rivaroxaban may protect artery walls better than warfarin. Mice on rivaroxaban had more stable plaques and less stiff blood vessels in an 18-week study. Human clinical trials are needed before drawing firm conclusions about heart protection in people.
Should I switch from warfarin to rivaroxaban based on this study?
No single study should guide a medicine change. This 2026 study was done in mice, and blood thinner decisions depend on your health history, kidney function, and clotting risk. Talk with your doctor before changing any prescription, and never stop warfarin without medical guidance.
What does warfarin do to blood vessels according to recent research?
Warfarin has been linked in earlier research to vascular calcification, a hardening of blood vessel walls caused by calcium buildup. It works partly by interfering with vitamin K pathways. This 2026 mouse study found that switching to rivaroxaban reduced calcification compared with continued warfarin use.
Want to Apply This Research?
- Log which blood thinner you take, the dose, and the date of any change. Also record your doctor’s latest blood pressure, cholesterol, and blood clotting test results when available. Keeping these numbers together makes it easier to share an accurate history with your healthcare provider.
- Set a reminder to take your blood thinner at the same time each day, and note any missed doses in the app. If you are taking warfarin, log your diet’s vitamin K intake, such as leafy greens, because changes in vitamin K can affect warfarin’s strength. Discuss any planned medicine changes with your doctor before acting on them.
- Review your logged medicine history and any test results with your doctor at each scheduled visit, usually every few months. Track trends over time rather than single readings. Over the long term, you can use the app to note symptoms such as chest pain, shortness of breath, or unusual bruising, and share them with your care team promptly.
This article summarizes an early animal study and is for general information only. It is not medical advice. The research was done in mice, and results may not apply to people. Do not start, stop, or change any blood thinner without consulting your doctor or pharmacist, as stopping anticoagulants suddenly can increase the risk of clots, stroke, or bleeding.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.