August 28, 2026 — A widely used heart-health test may be less useful for many people than previously believed, according to new research that suggests coronary artery calcium scans are most valuable for patients whose risk of heart disease falls into an uncertain middle range.
The test, known as a coronary artery calcium, or CAC, scan, uses a CT scan to look for calcium deposits in the arteries that supply blood to the heart. Calcium in these arteries is a sign of plaque buildup, and higher scores generally indicate a greater risk of cardiovascular problems.
The new study, published in JAMA, examined whether adding a CAC score to a newer cardiovascular risk calculator actually improves doctors' ability to identify people who are likely to experience a heart attack or stroke.
Risk calculator may already provide enough information
Researchers studied more than 6,000 adults between ages 45 and 79 who received both a CAC scan and an assessment using the American Heart Association's PREVENT risk calculator.
Participants were then followed for about a decade to determine how accurately the two approaches predicted future cardiovascular events.
The researchers found that adding calcium scores made little difference across the overall study population. For most participants, the PREVENT calculator alone was sufficient to place them into an appropriate risk category.
The finding could have important implications as CAC scans become increasingly accessible and affordable.
The test may matter most for people in the middle
The researchers found a clearer benefit among people whose predicted risk was neither clearly low nor clearly high.
For people classified as having borderline or intermediate risk — roughly a 3 percent to 9 percent chance of cardiovascular disease over 10 years — a calcium score could help doctors make a more informed decision about treatment.
In these cases, the scan can function as a kind of tiebreaker.
A score showing calcium in the coronary arteries can strengthen the case for cholesterol-lowering treatment, while a score of zero may allow some patients to postpone medication, depending on their overall circumstances and discussions with their doctors.
What a calcium score actually measures
A CAC scan does not directly measure whether someone will have a heart attack. Instead, it detects calcified plaque in the coronary arteries.
A score of zero generally means no detectable calcified plaque and is associated with relatively low cardiovascular risk. A score above zero indicates some degree of coronary artery disease, while increasingly high scores generally correspond to greater risk.
That information can be useful when treatment decisions are unclear. But the new findings suggest that ordering the test for everyone may not provide additional information that changes medical care.
Why the PREVENT calculator is important
The PREVENT calculator considers a range of factors already known to influence cardiovascular risk. These include age, sex, blood pressure, cholesterol levels, smoking status, diabetes and kidney function.
Because the tool incorporates many of these variables, researchers found that it could accurately identify most people who were likely to experience a cardiovascular event without requiring an additional imaging test.
That is important because a CAC scan involves radiation, costs money and may not change treatment when a patient's risk is already clearly established.
If someone is already at high risk, a doctor may recommend cholesterol-lowering treatment regardless of the calcium score. Conversely, a person with clearly low risk may not need medication simply because a scan confirms a low level of plaque.
Some patients may still benefit from scanning
The study does not mean CAC scans are useless.
Doctors say the test can provide valuable additional information for patients whose risk is difficult to classify. A scan may also be considered in certain people with risk-enhancing factors that are not fully captured by standard calculators.
These can include a strong family history of heart disease, pregnancy-related conditions such as preeclampsia or gestational diabetes, or elevated levels of lipoprotein(a), a cholesterol-related particle associated with cardiovascular risk.
A calcium score may also provide additional information among people already considered high-risk. Very high scores can indicate a substantially greater burden of coronary disease and could influence decisions about how aggressively to manage cardiovascular risk.
Lifestyle remains important
Regardless of whether someone undergoes a CAC scan, doctors emphasize that the fundamentals of heart-health prevention remain important.
Maintaining a nutritious diet, exercising regularly, getting adequate sleep, avoiding tobacco and controlling blood pressure and cholesterol can all help reduce cardiovascular risk.
The study therefore does not suggest that people should ignore their heart health if they do not need a calcium scan. Instead, it highlights the importance of using the right test for the right patient.
A more targeted role for CAC testing
The findings suggest that coronary calcium scanning may be most effective when used selectively rather than as a routine test for everyone concerned about heart disease.
For people at clearly low or high risk, the scan may simply confirm what doctors already know. But for those in the middle — particularly patients deciding whether to begin preventive treatment — the additional information from a CAC score may help guide that decision.
Researchers and cardiologists say the results should therefore be viewed less as a rejection of calcium testing and more as evidence for using it strategically.
For patients wondering whether they should have a CAC scan, the most appropriate first step is to discuss their overall cardiovascular risk with a health-care professional rather than ordering the test solely for reassurance.
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