A coronary artery calcium (CAC) score is a quick, no-dye CT scan of the heart; a score of 0 means no calcium was seen, any score above 0 points toward cholesterol treatment (especially 100 or more), and the test helps most when a statin decision is truly uncertain.
A cholesterol panel and a risk calculator estimate your chance of heart disease. A calcium scan looks for calcified plaque in the heart arteries themselves, so it can help settle a statin question the other two leave open.
Where it ranks in the book: The calcium scan is Add next (as a test), only when a statin decision is truly uncertain, mainly at intermediate risk or selected borderline risk. It's not needed with familial hypercholesterolemia (FH) or an LDL of 190 or more. A repeat scan once you're on a statin is a Skip. (Tests get priorities in the book, not grades.)
What is a coronary calcium scan?
Also called a CAC scan or coronary artery calcium test, it's a quick CT scan of the heart, with no dye and no needle. It looks for calcium in the heart arteries, which is a sign of plaque (2026 ACC/AHA guideline).
- Radiation: about 1 millisievert per scan, about what you'd get from a few months of the natural background radiation everyone lives with.
- Cost: coverage varies, so ask before you book.
- Surprises: in fewer than 10% of adults, the scan picks up something unrelated, such as a small spot on a lung, and some need more tests. A few people feel anxious after the results, so talk that through first.
Who should get a calcium score test?
The scan is aimed at people at intermediate risk, and select people at borderline risk, when the decision about cholesterol medicine is still uncertain. It's generally meant for men 40 and older and women 45 and older.
The 2026 guideline uses it as a tie-breaker, after your 10-year risk has been calculated and adjusted for things like family history.
A zero helps most for people who qualify for a statin and want to know whether starting one can wait.
Who doesn't need it:
- People with FH or an LDL of 190 or more. Their risk is already high, and a statin helps them whatever the score.
- People who've had a heart attack or stroke. The 2026 guideline already puts a cholesterol medicine in their plan.
Calcium score ranges
The score is reported in Agatston units:
- 0: no calcium seen.
- 1 to 99: minimal to mild.
- 100 to 299: moderate.
- 300 to 999: severe.
- 1,000 or more: extensive.
Your report may also give a percentile for your age. For LDL goals, the guideline groups a score at the 75th percentile or higher with scores of 100 to 299.
What a calcium score of 0 means
A zero is very reassuring. In a US study of about 6,800 adults followed for about 10 years, only 4.0% of those with a zero had a heart attack, stroke or other heart event. Of 13 reassuring findings compared, a zero lowered predicted risk the most (MESA study).
As many as 40% of people at intermediate risk have a zero. For them, the guideline says it's reasonable to hold off on starting a statin and repeat the scan in 3 to 7 years.
The pause has a time limit. About 20% to 25% of lower-risk people develop some calcium within 5 to 7 years, and intermediate-risk people get there sooner, in 3 to 5 years.
When a zero doesn't clear you:
- Diabetes after age 40. A zero went with low event rates for about 5 years, and then risk climbed a lot.
- Current smoking. Smokers with a zero had death rates like nonsmokers with mild to moderate calcium.
- A strong family history of early heart disease. With one affected parent, brother or sister, a zero still meant a low 10-year risk. With several close relatives, it may not be that reassuring.
- FH or an LDL over 190.
Soft plaque without calcium can also hide behind a zero. In a Swedish study, about 5.5% of people with a zero had noncalcified plaque on a more detailed scan. A CT angiogram, which uses dye, shows soft plaque too, but it's reserved for select people.
What a high calcium score means
A score above zero means plaque is there. For people at intermediate risk, and some at borderline risk, the guideline recommends starting cholesterol treatment, especially at 100 or higher.
- 100 or more: the 10-year event rate runs above 7.5%, the line the older US calculator used for recommending a statin.
- 300 or more: event rates look like those of people who already have heart disease.
- Younger adults: even a small score matters. In people aged 32 to 46, scores as low as 1 to 19 were tied to more coronary events.
The score also seems to show who gains most from a statin. In about 13,600 people followed for about 9 years, statins were linked to fewer heart attacks and strokes in people with any calcium, but not in people with a zero (calcium and statin study). Over 10 years:
- With a score over 100, about 12 people needed to take a statin to prevent one heart attack or stroke.
- With a score of 1 to 100, it was about 100, and that smaller benefit could have been chance.
Statins weren't handed out at random in that study, so the people taking one may have differed in other ways.
High calcium score treatment: the LDL goals
If you start treatment, the 2026 guideline sets an LDL goal by score. All numbers are mg/dL:
- Score 1 to 99 (and below the 75th percentile for your age): LDL under 100.
- Score 100 to 299 (or 75th percentile or higher): LDL under 70.
- Score 300 to 999: LDL under 70, with under 55 a reasonable option.
- Score 1,000 or higher: LDL under 55.
Lifestyle goes alongside the medicine and never replaces it.
Don't repeat the scan once you're on a statin
The guideline says not to repeat a calcium scan once cholesterol treatment has started. Statins often raise the score, even while they steady the plaque and lower the risk. A higher number on a statin doesn't mean your treatment is failing.
A scan also isn't a test of whether you can stop a statin, even one you started years ago. That question belongs in a visit with your doctor.
If a chest CT for another reason, such as lung cancer screening, mentions calcium in the heart arteries, bring it up at your next visit. No calcium on that kind of scan is less reliable, with misses reported in up to 24%.
What calcium scans haven't proven
No trial has shown yet that scanning people lowers heart attacks or deaths.
- In a Danish trial of about 46,600 men aged 65 to 74, an invitation to a screening package that included a calcium scan didn't lower deaths enough to rule out chance (DANCAVAS trial).
- In a 2026 US trial of about 5,800 people, choosing statins by calcium score instead of by the older calculator gave similar event rates, near 3% in both groups. The trial was too small to show the two approaches were equal. People told to take a statin because of their scan stuck with it far more often, 62% compared with 23% (CorCal conference report). The full paper hasn't been published yet.
Safety: when to call your doctor
- A score of 100 or more is a reason to call your doctor's office and set up a visit, not to panic.
- Don't stop a statin because a calcium score was zero.
- Chest pain or pressure, shortness of breath, or sudden weakness, numbness or trouble speaking means emergency help right away, whatever your score says.
Bottom line
A coronary calcium scan is a quick, low-radiation CT that looks for calcified plaque in the heart arteries. It's most useful as a tie-breaker on a statin decision, usually for men 40 and older and women 45 and older at intermediate risk. A zero lets many people put off starting a statin, with a rescan in 3 to 7 years, and any score above zero points toward treatment, especially 100 or more. Don't repeat it once you're on a statin, since statins often raise the score.
Questions people ask
What is a good or normal calcium score?
Zero is the best result, with only 4.0% having a heart event over about 10 years in one large study. Scores of 1 to 99 are minimal to mild, 100 to 299 moderate, 300 to 999 severe, and 1,000 or more extensive.
Is a calcium score test worth it?
It's worth it when the answer would change your plan, usually at intermediate or borderline risk when a statin decision is uncertain. It isn't needed with FH, an LDL of 190 or more, or a past heart attack or stroke, and it shouldn't be repeated once you're on a statin.
How much radiation is in a CT calcium score scan?
About 1 millisievert, roughly a few months of the natural background radiation everyone gets.
Can you lower your calcium score?
Don't use the score to track treatment. Statins often push it up while they steady plaque and cut risk. The goal after a high score is a lower LDL, set by your score, along with blood pressure, blood sugar and not smoking.
What else the book ranks for your heart risk
Your Cholesterol by the Numbers, coming soon, covers the calcium scan with the other tests, and grades the foods and habits that lower LDL. A few that matter after a high score:
- Oats and barley, about 3 grams of beta-glucan a day: SUPPORTED (works), LDL about 7 to 10 mg/dL lower.
- Psyllium, about 10 grams a day: SUPPORTED (works), LDL about 13 mg/dL lower, and it adds to a statin.
- CoQ10 for statin aches: UNLIKELY TO HELP.
Read Lp(a): the inherited cholesterol number, the test the book says every adult should get once, and statin side effects: what the blinded trials show.