You can feel healthy, have no chest pain and have no history of heart disease and still have plaque building up inside your arteries.
That is one of the clearest messages from a major new study published in the New England Journal of Medicine. Researchers examined 16,808 adults ages 18 to 70 in Denmark and Spain and found signs of atherosclerosis in 57.1% of them.
The finding may sound alarming. But it needs some context.
The study does not mean that 57% of Americans or Californians have heart disease. It also does not mean that everyone should get a heart scan.
What it does show is that atherosclerosis, the buildup of plaque in artery walls, can be present years before a person knows anything is wrong.
The study, called REACT, included people divided into five age groups, with roughly equal numbers of men and women.
Researchers used 3D ultrasound to examine arteries in the neck and legs. They also used coronary CT angiography to look at the arteries supplying the heart.
Among adults ages 18 to 29, researchers detected atherosclerosis in 8.7% of men and 6.7% of women.
Put another way, roughly 1 in 13 young adults in the study had detectable plaque.
The plaque in younger participants was usually found outside the heart, in the arteries of the neck or legs, and was generally limited to one area. As people got older, plaque became more common, larger and more likely to appear in several arterial areas.
By ages 60 to 70, the prevalence had risen to roughly 9 in 10 participants.
“Silent” atherosclerosis does not mean someone is secretly having a heart attack.
In this study, “silent” refers to atherosclerosis that was detectable through imaging in people without known atherosclerotic cardiovascular disease.
Atherosclerosis is a process in which plaque builds up inside artery walls. Over time, that plaque can contribute to serious cardiovascular problems, including heart attacks and strokes.
The important point is that the process can begin long before symptoms appear.
Men and women did not show exactly the same pattern
The researchers also found differences between men and women.
Atherosclerosis became detectable earlier in men. Among women, researchers observed a later and steeper increase during midlife, around the typical age of menopause.
That is an important observation, but it does not prove that menopause itself caused the buildup of plaque.
The study shows the pattern. It does not prove the cause.
For more on the connection between menopause and cardiovascular health, see Parriva’s earlier guide on menopause and heart health.
Why this matters for the way we think about heart risk
Doctors already use information such as age, blood pressure, cholesterol levels and smoking history to estimate a person’s cardiovascular risk.
Those tools answer an important question:
How likely is this person to develop cardiovascular disease based on known risk factors?
The REACT study is asking a different question:
Can we actually see evidence of atherosclerosis already present in the arteries?
The study suggests that some people can have detectable plaque even when traditional risk assessment does not identify them as having a high estimated risk.
That does not make conventional risk assessment useless. It shows that risk estimation and imaging are answering different questions.
Cholesterol remains an important part of prevention. The new recommendations calling for earlier attention to LDL cholesterol and cardiovascular risk can be found in our report on the 2026 heart-health guidelines.
What the evidence shows
REACT found detectable atherosclerosis in more than half of its participants, including a measurable share of adults in their teens and 20s. The amount and distribution of plaque generally increased with age.
What the evidence does not show
The study does not show that every young adult should receive vascular imaging.
It does not establish that widespread CT or ultrasound screening would prevent heart attacks or strokes.
And it does not show that conventional cardiovascular risk assessment should be abandoned.
The study gives us a picture of how common detectable plaque was in this particular group. It does not by itself prove that finding plaque earlier and treating people differently will improve their long-term health.
That question needs further research.
What does this mean for Californians?
REACT was conducted in Denmark and Spain, not California. Its numbers therefore should not be treated as a direct estimate of how common silent atherosclerosis is among Californians.
But cardiovascular health is an important California issue.
You can learn more about California’s cardiovascular data among Latino residents, including heart disease, stroke and hypertension in our report on cardiovascular disease among California Latinos
That California reporting provides useful local context, but it is important not to mix the two studies.
REACT tells us about silent atherosclerosis in adults studied in Denmark and Spain. California data tell us about cardiovascular health here. Neither should be used to stand in for the other.
So what should you do with this information?
Probably not panic and not assume you need a CT scan.
A more useful takeaway is that feeling healthy does not make cardiovascular prevention irrelevant.
Know your blood pressure. Know your cholesterol. Don’t smoke. Pay attention to diabetes and family history. If you have questions about your individual heart risk, talk with a health professional who can consider your medical history and risk factors.
The bigger lesson from REACT is simple:
Heart disease does not necessarily begin when the first symptom appears. The process can be developing quietly for years.
Understanding that may give doctors another way to think about prevention. But the research still has to show whether seeing that hidden plaque earlier actually leads to better health outcomes.
