A coronary artery calcium scan can turn a vague concern about heart disease into a number.
But what does a CAC score mean?
CAC stands for coronary artery calcium. A CAC score measures the amount of calcified plaque detected in the arteries that supply blood to the heart. The result can help doctors estimate cardiovascular risk and decide whether more intensive prevention may be appropriate.
A CAC score is not a diagnosis, a guarantee that a heart attack will or will not occur, or a substitute for medical care. It is one piece of evidence that can help a clinician and patient make a more informed decision about cholesterol treatment and other heart-health strategies.
The American College of Cardiology and American Heart Association updated their cholesterol guidance in 2026 and now place greater emphasis on selective CAC testing when cardiovascular risk or the need for lipid-lowering treatment remains uncertain.
What Does a CAC Score Mean?
A CAC score comes from a noncontrast CT scan of the heart. The scan looks for calcium deposits in the coronary arteries and calculates an Agatston score based on the amount and density of detected calcium.
Put simply:
The higher the CAC score, the more calcified coronary plaque has been detected.
A higher CAC burden is generally associated with a higher risk of cardiovascular events than a lower score. But the number should always be interpreted alongside other factors, including age, blood pressure, cholesterol, diabetes, smoking, family history and other cardiovascular risk factors.
The American College of Cardiology’s 2026 discussion of the updated dyslipidemia guideline explains how CAC can be used to refine cardiovascular risk and guide decisions about lipid-lowering treatment.
What a CAC scan does—and does not—show
A CAC scan detects calcified plaque, not every type of plaque.
Some coronary plaque can be noncalcified and may not appear on a calcium scan. The test also does not directly show how severely an artery is narrowed.
That distinction is important.
Someone can have a high CAC score without experiencing chest pain, while someone with new chest pain may need a completely different type of evaluation even if their CAC score is zero.
RadiologyInfo explains that a calcium score measures calcified plaque and does not determine whether a particular coronary artery is narrowed.
CAC Score Ranges: What Do They Mean?
There is no single CAC number that tells every person exactly what treatment they need. Age, sex, existing medical conditions, cholesterol levels and other risk factors matter.
Still, these broad categories are commonly used to explain CAC results:
| CAC score | General interpretation | What it may mean for prevention |
|---|---|---|
| 0 | No detectable coronary calcium | Generally associated with lower short-term cardiovascular risk, but does not mean zero risk |
| 1–99 | Mild amount of calcified plaque | Indicates coronary atherosclerosis is present; overall risk and age help determine next steps |
| 100–399 | Moderate plaque burden | Generally associated with higher cardiovascular risk and often warrants a more intensive prevention discussion |
| 400+ | Extensive calcified plaque | Indicates a substantial plaque burden and warrants careful clinical evaluation and risk-factor management |
| 1,000+ | Very high plaque burden | Represents extensive coronary calcium and generally places the patient in a substantially higher-risk category |
These categories are descriptive, not automatic treatment instructions.
The 2026 ACC/AHA guideline describes CAC as a tool for refining risk and helping determine the intensity of LDL-lowering treatment. It specifically notes that CAC can help when the decision about treatment is uncertain.
What does a CAC score of 0 mean?
A CAC score of 0 means that no coronary artery calcium was detected on the scan.
For many people without symptoms, this is reassuring and is associated with a relatively low near-term risk of cardiovascular events.
But CAC = 0 does not mean zero heart disease risk.
A person can still have:
- Noncalcified plaque
- High LDL cholesterol
- Diabetes
- High blood pressure
- A strong family history of early heart disease
- Smoking-related cardiovascular risk
- Other factors that increase cardiovascular risk
The 2026 ACC/AHA guidance says a CAC score of zero can support deferring lipid-lowering treatment in certain lower- or intermediate-risk people when other important risk conditions are absent.
That is different from saying everyone with a CAC score of zero should stop or avoid cholesterol medication.
What does a CAC score of 1–99 mean?
A score between 1 and 99 means that some calcified coronary plaque was detected.
The finding can be particularly informative in younger adults because coronary calcium is less common at younger ages.
A CAC score in this range generally means that coronary atherosclerosis is already detectable, even if the person has no symptoms.
The appropriate response depends on the patient’s overall cardiovascular risk and the reason the CAC test was performed.
What does a CAC score of 100–399 mean?
A score between 100 and 399 indicates a larger burden of calcified plaque.
This finding generally deserves a more detailed discussion of cardiovascular risk, cholesterol levels, blood pressure, diabetes, smoking and lifestyle.
The 2026 ACC/AHA guideline emphasizes lowering LDL cholesterol according to the individual’s overall risk and the amount of coronary calcium detected.
What does a CAC score of 400 or higher mean?
A CAC score of 400 or higher indicates a substantial amount of calcified coronary plaque.
It does not mean that a heart attack is about to happen, and it does not automatically mean an artery is completely blocked.
However, a high score is an important finding that deserves a careful review with a healthcare professional.
Depending on the person’s symptoms and overall risk, the clinician may focus on more intensive management of LDL cholesterol and other cardiovascular risk factors and may consider whether additional evaluation is appropriate.
Why Does Age Matter When Interpreting a CAC Score?
The same CAC score can mean different things for people of different ages.
For example, a CAC score of 50 may have a different significance in a 45-year-old than in a 75-year-old.
Some reports therefore provide a CAC percentile, which compares a person’s score with people of similar age and sex.
The percentile can provide useful context, but it should not replace consideration of the actual calcium score and the person’s overall cardiovascular risk.
This is particularly important when CAC is used to refine a treatment decision rather than simply to describe the presence of coronary plaque.
Why Might a Doctor Recommend a CAC Scan?
CAC testing is primarily useful when a person does not have known coronary artery disease and the decision about preventive treatment remains uncertain.
The 2026 ACC/AHA dyslipidemia guideline recommends selective use of CAC testing for men age 40 and older and women age 45 and older with borderline or intermediate estimated cardiovascular risk when the result could help with the decision about lipid-lowering treatment.
For example, imagine two people with similar LDL cholesterol levels.
One may have little or no detectable coronary calcium, while another may have substantial calcified plaque.
That information can change the discussion about cardiovascular risk and the potential benefits of treatment.
This is why CAC is sometimes described as a risk-refinement tool rather than simply another heart test.
For more information about how cholesterol, blood pressure, diabetes and other factors fit into preventive care, see Good Morning Healthcare’s Preventive Screening Checklist: What Tests Do You Really Need?.
CAC Score and Statins: What Is the Connection?
One of the most common reasons a doctor may order a CAC scan is to help decide whether cholesterol-lowering treatment is appropriate when the answer is not obvious.
The older ACC/AHA framework commonly used these CAC thresholds:
- CAC = 0: In selected patients, statin therapy could be deferred when higher-risk conditions were absent.
- CAC 1–99: Statin therapy generally became more favorable, particularly in adults age 55 and older.
- CAC ≥100 or ≥75th percentile: Statin therapy was generally favored.
The 2026 ACC/AHA dyslipidemia guideline has updated the broader framework. It emphasizes CAC as part of a more comprehensive risk assessment and sets LDL-C goals based on overall risk and the degree of subclinical atherosclerosis.
That means patients should not look at a CAC number and independently decide whether to start, stop or change medication.
Instead, the number should be part of a clinician-patient discussion.
Good Morning Healthcare’s article New Statin Guidelines: Why More Americans May Be Eligible explains the 2026 changes in cholesterol treatment and how CAC fits into the broader risk discussion.
A High CAC Score Does Not Automatically Mean You Need a Stent
This is one of the most important points for patients to understand.
A CAC scan measures calcified plaque burden. It does not directly show whether a specific coronary artery is severely narrowed.
Therefore, a high CAC score does not automatically mean that someone needs:
- A stent
- Coronary angioplasty
- Bypass surgery
- Cardiac catheterization
Additional testing may be appropriate in some situations, particularly when symptoms suggest possible obstructive coronary artery disease.
A person with a high CAC score but no symptoms may have a very different evaluation from someone with a high score who has exertional chest pressure or shortness of breath.
What About a CAC Score of Zero and Chest Pain?
A CAC score of zero can be reassuring in an asymptomatic person undergoing risk assessment.
But it should not be used to dismiss new or concerning symptoms.
A calcium scan is not designed to diagnose an acute heart problem.
If someone develops new chest pressure, chest pain, shortness of breath, sweating, nausea, fainting or pain that spreads to the arm, jaw, back or shoulder, they should seek appropriate medical evaluation rather than relying on an old CAC score.
A calcium score is a preventive risk-assessment tool—not an emergency test.
What Happens During a CAC Scan?
A CAC scan is a relatively quick, noninvasive CT examination.
The patient lies on a CT table while images of the heart are obtained. A calcium-scoring scan generally does not require an injection of contrast dye.
The scan itself can take only a few minutes, although the total appointment may be longer.
RadiologyInfo notes that cardiac CT calcium scoring is noninvasive, does not require contrast material and typically takes less than 20 minutes.
Does a CAC scan involve radiation?
Yes.
Because CT uses X-rays, there is some radiation exposure. The dose varies depending on the scanner and protocol.
The risk from a single calcium scan is generally considered low, but radiation exposure is one reason medical imaging should have a clear clinical purpose.
CAC testing is also not generally used simply as a routine screening test for everyone.
What Are the Limitations of a CAC Score?
A CAC score can be useful, but it has important limitations.
It does not detect all plaque
Noncalcified plaque may not appear on the scan.
It does not show the exact degree of blockage
A high score indicates a greater burden of calcified plaque but does not tell you that a particular artery is 70%, 80% or 90% blocked.
It does not diagnose a heart attack
Someone with active symptoms needs appropriate diagnostic evaluation.
It does not replace traditional risk assessment
Blood pressure, LDL cholesterol, diabetes, smoking, age, family history and other factors remain important.
It can lead to additional testing
An unexpected finding may prompt additional imaging or medical evaluation. That may be useful, but it can also result in additional costs, radiation exposure or anxiety.
RadiologyInfo specifically notes that a high calcium score may lead to additional cardiac testing and that the score should be considered as part of the overall risk picture.
Should You Repeat a CAC Scan?
There is no universal schedule for repeating CAC scans.
The answer depends on why the original test was performed, the person’s age and risk factors, and whether the result would actually change management.
A repeat scan should not be viewed simply as a way to see whether the number went up or down.
In fact, CAC scores can increase over time as plaque becomes more calcified. A rising calcium score does not necessarily mean that treatment is failing.
The more important goal is reducing the risk of heart attack and stroke, not achieving a particular calcium number.
Discuss the potential value and timing of repeat testing with your clinician.
What Should You Ask After Receiving Your CAC Score?
When you receive your report, don’t focus only on the number.
Ask:
- What is my CAC score?
- What is my CAC percentile for my age and sex?
- What does the score mean in the context of my overall cardiovascular risk?
- What is my LDL cholesterol goal?
- Should I start or change cholesterol-lowering treatment?
- Do my blood pressure, diabetes or smoking history change the interpretation?
- Does my family history of early heart disease matter?
- Do I have symptoms that require another type of heart test?
- Would additional testing change my treatment?
- Would repeating the CAC scan provide useful information?
These questions can turn a confusing number into a practical prevention plan.
CAC Score vs. Other Heart Tests
A CAC scan is only one type of cardiovascular test.
| Test | What it primarily evaluates | Typical purpose |
|---|---|---|
| CAC scan | Calcified plaque in coronary arteries | Refining cardiovascular risk |
| Coronary CT angiography | Coronary artery anatomy and plaque/narrowing | Evaluating suspected coronary artery disease |
| Nuclear stress test | Blood flow to heart muscle during stress | Looking for stress-related blood-flow abnormalities |
| Stress echocardiogram | Heart function and wall motion during stress | Evaluating how the heart responds to stress |
| Exercise ECG | Electrical activity during exercise | Looking for exercise-related ECG changes and rhythm abnormalities |
For example, a CAC scan can tell you that calcified plaque is present, while a nuclear stress test asks a different question: Does blood flow to the heart muscle become inadequate when the heart is stressed?
Our Good Morning Healthcare guide, What Does a Nuclear Stress Test Show?, provides more information about that test.
The Bottom Line: What Does a CAC Score Mean?
So, what does a CAC score mean?
It is a measurement of the amount of calcified plaque detected in the coronary arteries.
In general, a higher score means a greater burden of calcified coronary plaque and a higher cardiovascular risk than a lower score. But the number should never be interpreted in isolation.
A CAC score of 0 can be reassuring for many people, but it does not eliminate cardiovascular risk.
A CAC score above 0 means coronary calcium has been detected and provides evidence of coronary atherosclerosis.
A higher CAC score generally means that prevention deserves greater attention, but it does not automatically mean a person needs a stent or bypass surgery.
The most useful question is not simply:
“Is my CAC score high or low?”
It is:
“What does my CAC score mean when combined with my age, cholesterol, blood pressure, diabetes status, family history, symptoms and overall cardiovascular risk—and does it change what I should do next?”
Frequently Asked Questions
What is a normal CAC score?
A CAC score of 0 means no detectable coronary calcium was found. It is generally considered the lowest CAC category, although it does not mean that a person has zero cardiovascular risk.
Is a CAC score of 100 considered high?
A score of 100 indicates a meaningful amount of calcified coronary plaque. It is associated with greater cardiovascular risk than a score of zero, but treatment decisions depend on the person’s overall risk profile and current guidelines.
What does a CAC score of 400 mean?
A CAC score of 400 or higher indicates a substantial burden of calcified coronary plaque. It does not automatically mean an artery is severely blocked or that a stent is required, but it warrants careful cardiovascular risk assessment.
Can you have a heart attack with a CAC score of 0?
Yes. A CAC score of zero substantially lowers risk for many asymptomatic people but does not eliminate the possibility of cardiovascular disease or a future heart attack. Noncalcified plaque and other risk factors can still be present.
Does a high CAC score mean I need a statin?
Not necessarily based on the number alone, but CAC can strongly influence the discussion about lipid-lowering treatment. The 2026 ACC/AHA guideline uses CAC as an important tool for refining risk and determining appropriate LDL-lowering goals and treatment.
Does CAC score show blocked arteries?
No. CAC measures calcified plaque, not the percentage of narrowing in an individual coronary artery. Additional testing may be needed when doctors need information about coronary anatomy or blood flow.
How often should a CAC scan be repeated?
There is no one-size-fits-all schedule. Whether to repeat the scan depends on the original score, age, risk factors and whether a new result would change management.
Reviewed by Nancy Kumar, Chief Editor
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