How to Order a Coronary Artery Calcium Score Test

Getting a coronary artery calcium (CAC) score test usually starts with a conversation with your primary care doctor or cardiologist, who can write an order for the scan or refer you to an imaging center. In some areas, you can also self-refer and pay out of pocket, since the test is often not covered by insurance. The scan itself is quick and painless, but the real question for most people is whether they actually need one, because the test is most useful for a specific slice of the population, and the results change medical decisions only in certain risk categories.

Who Should Ask for This Test

Guidelines from the American College of Cardiology (ACC) and American Heart Association (AHA) recommend CAC scoring primarily for people at borderline or intermediate risk of cardiovascular disease, meaning a 10-year risk roughly between 5% and 20% based on standard risk calculators.¹ That’s the group where the result actually tips the decision on whether to start a statin or take other preventive steps. If your calculated risk is very low, the scan is unlikely to change your treatment plan. If your risk is clearly high, you should already be on preventive therapy regardless of what the scan shows.

The guidelines also mention “risk-enhancing factors” that can push someone toward getting scanned. These include things like a family history of premature heart disease, South Asian ancestry, metabolic syndrome, chronic inflammatory conditions, or elevated blood markers like high-sensitivity C-reactive protein.² If you have one or more of those factors and your doctor is on the fence about starting medication, CAC scoring can be the tiebreaker. The European Society of Cardiology has similar recommendations, endorsing the test for risk refinement in primary prevention settings.

How to Actually Get One Ordered

The most straightforward path is to bring it up at a routine checkup. If you fall into the borderline-to-intermediate risk zone, or if you have risk-enhancing factors and your doctor hasn’t mentioned the test, ask directly. Many physicians appreciate the prompt, because the test genuinely helps when the treatment decision is ambiguous. Your doctor writes a prescription or referral to an imaging center that performs cardiac CT.

If your doctor is unfamiliar with CAC scoring or doesn’t think you need it, you still have options. Many hospital-based imaging departments and freestanding radiology clinics offer CAC scans on a self-pay, walk-in, or self-referred basis. Some preventive cardiology practices market the test directly to patients. A self-referral means you schedule and pay without a doctor’s order, though you’ll want a physician to interpret the results and put them in the context of your overall health. Getting a number without understanding what it means for you personally is not particularly helpful.

What the Scan Costs and Whether Insurance Pays

The test typically costs under $200 out of pocket, which makes it one of the cheaper screening tests in medicine.³ Many imaging centers charge between $75 and $150, though prices vary by region. The scan takes about five minutes and requires no contrast dye, no fasting, and no special preparation besides briefly holding your breath a few times.

The catch is that most private insurers and Medicare do not cover CAC scoring as a preventive screening test. You’ll usually pay out of pocket. Texas has passed legislation mandating insurance coverage of the test for appropriately selected individuals, and advocacy groups have pushed for broader coverage nationally, but for now, expect to pay yourself in most states.³ Some people find this frustrating given that the test costs a fraction of colonoscopies and mammograms, which insurance routinely covers. That said, $100 to $200 remains a barrier for some people, and research has flagged socioeconomic status as a factor in who actually gets scanned.⁴

What Happens During the Test

You lie on a CT scanner table, electrodes are placed on your chest to sync the scan with your heartbeat, and the machine takes images of your coronary arteries in a few seconds. The whole visit, including changing clothes and setup, usually wraps up in about 15 minutes. No IV line, no injections, no sedation. You can drive yourself home and go about your day normally.

The scan uses a low dose of radiation. Across large studies, the average effective dose comes in around 1 millisievert (mSv), which is roughly the amount of background radiation you absorb from the environment in about four months.⁵ A study of over 82,000 people confirmed a mean dose of about 1 mSv, with no meaningful variation by age or sex. People with a BMI above 30 tend to receive somewhat higher doses because scanners need to work harder to produce a clear image through more tissue.⁶ Even so, the radiation from a CAC scan is much lower than a standard chest CT, which delivers roughly 7 mSv. For most people getting a single scan, the risk from radiation is negligible.

Reading Your Results

Your report will include an Agatston score, which is the standard way calcium deposits are quantified. It will also ideally include your percentile relative to your age, sex, and race, along with which vessels are affected and whether there’s calcium in the left main coronary artery, which carries particular significance.⁷ The broad categories break down roughly like this:

Score of 0: No detectable calcified plaque. In people at borderline or intermediate risk, this can be used to safely delay statin therapy in many cases.
Score of 1–99: Mild calcium buildup. Statin therapy is favored, especially after age 55.
Score of 100 or above: Moderate to heavy calcium. If this puts you at or above the 75th percentile for your age and sex, guidelines recommend statin therapy regardless of age.
Score above 1,000: Very heavy calcium burden. These patients deserve special attention and aggressive risk management.

The ACC/AHA guidelines carve out exceptions to the “zero means you can skip the statin” rule. If you have diabetes, a strong family history of premature heart disease, or you smoke, statins may still be recommended even if your score is zero.⁸

The Power of a Zero Score and Its Limits

A score of zero is reassuring. It’s associated with very low rates of heart attacks and cardiovascular events over the following decade, and it can be used to safely avoid starting someone on lifelong medication they may not need.⁹ In one study, among people with risk-enhancing factors, a CAC of zero was associated with event rates below the threshold that would normally trigger statin therapy, with one exception: people with a low ankle-brachial index still had elevated event rates even with zero calcium.¹⁰

But zero does not mean your arteries are perfectly clear. The scan only detects calcified plaque. Early or unstable lesions, sometimes called “soft plaques,” contain no calcium and won’t show up.¹¹ One study using CT angiography to look more closely at people with zero calcium found that about 6.5% had detectable non-calcified plaque, including a small fraction with blockages narrowing more than half the artery.¹² A meta-analysis of diagnostic accuracy found that among patients with an Agatston score of zero, 17% turned out to have obstructive coronary artery disease when evaluated by CT angiography.¹³ That 17% figure comes from patients who already had symptoms and clinical indications for further testing, so it doesn’t apply to asymptomatic screening populations. Still, it’s a reminder that the CAC score is a risk-stratification tool, not a guarantee of clean arteries.

How CAC Scoring Reclassifies Risk

One of the strongest arguments for the test is that it frequently moves people into different risk categories compared to what standard calculators predict. In one study, adding the CAC score to a standard risk assessment led to reclassification of 46% of patients. Among those originally categorized as borderline risk, 83% were reclassified, and the majority moved down into the low-risk group.¹⁴ That reclassification matters because it determines whether your doctor recommends a statin, aspirin, or other interventions. Another study found that traditional risk scores overestimate or underestimate risk in a substantial portion of asymptomatic middle-aged patients, and adding the calcium score significantly improved accuracy.¹⁵

This reclassification cuts both ways. Some people who thought they were fine discover they have significant calcium deposits and need treatment. Others who were already anxious about heart disease, or whose doctors were leaning toward prescribing a statin, get a zero score and can reasonably hold off. Either outcome is clinically useful, and both represent the test doing its job.

People With a Family History of Early Heart Disease

If a close relative had a heart attack or needed a coronary procedure before age 55 (for men) or 65 (for women), you’re in a group where CAC scoring is especially informative. Family history of premature heart disease is strongly linked to the presence of coronary calcium, and a sibling history appears to be an even stronger association than parental history.¹⁶

Data from the Multi-Ethnic Study of Atherosclerosis found that among people reporting a family history of premature heart disease, nearly half had a CAC score of zero. Those individuals had low event rates and may receive less net benefit from aspirin or statin therapy. Meanwhile, those in the same family-history group whose CAC score was 400 or higher had event rates roughly three times higher than the zero-calcium group.¹⁷ In other words, “I have a family history” alone is not precise enough to decide treatment. The CAC score separates the people in that group who actually have subclinical disease from those who don’t.¹⁸

People With Type 2 Diabetes

Diabetes is another area where CAC scoring adds precision. A long-term cohort study found that patients with type 2 diabetes who had a CAC score of 10 or higher had an average cardiovascular disease risk about eight times higher than those with a score below 10. As the score climbed into higher categories, risk escalated dramatically, reaching nearly 39 times higher in the most extensive calcium group.¹⁹ Patients with diabetes and a score below 10 maintained very low rates of cardiovascular events for at least 10 years.

A separate long-term study of asymptomatic people with type 2 diabetes found that increasing calcium scores independently predicted major adverse cardiac events, with no heart attacks at all observed in those with a zero score.²⁰ Keep in mind that guidelines still lean toward statin therapy for diabetic patients broadly, but the CAC score helps quantify just how aggressive treatment should be and how urgently additional interventions are needed.

When to Repeat the Test

If your initial score is zero, research suggests that conversion to detectable calcium happens at low frequency before four years, and no clinical factor reliably predicts who converts early.²¹ Guidelines suggest re-scanning in five to 10 years if the initial score is zero and your risk factors haven’t changed. Repeating the test sooner than four years after a zero result is unlikely to provide useful new information.

For people with nonzero scores, there’s less consensus on when to repeat. Some clinicians use follow-up scans to track whether calcium is progressing and whether treatments are working, but the evidence base for routine serial scanning in that group is thinner, and most guidelines focus on the initial scan as a one-time decision-support tool rather than a monitoring test.

What the Scan Might Find Besides Calcium

Because the CT covers part of your chest, the scan occasionally picks up findings unrelated to your coronary arteries. In one study of diabetic patients, about 16% had incidental findings, mostly lung abnormalities like pulmonary nodules.²² Most of these nodules are benign, but they trigger follow-up imaging. One study of patients in whom pulmonary nodules were flagged found no malignant lesions among the group, yet chest CT use jumped dramatically after notification, with the average person receiving more than one follow-up scan.²³ About a third of the time, the original nodule couldn’t even be found on follow-up. This is the classic screening tradeoff: finding something incidental can occasionally be life-saving, but it more often leads to extra scans, anxiety, and cost without changing outcomes.

Why Knowing Your Score Changes Behavior

One underappreciated benefit of the test is motivational. Seeing a concrete number representing calcium in your arteries appears to make people take prevention more seriously. In one study, statin adherence rose steadily with higher CAC scores: about 27% of people with a zero score stayed on their statin, compared to roughly 59% of those with scores of 400 or higher. Weight loss followed a similar gradient.²⁴ Another study found that 91% of individuals with the highest baseline calcium scores adhered to statin therapy, compared to 44% in the lowest group.²⁵ A systematic review confirmed the trend across most studies: seeing calcium in your arteries improves medication adherence and likely motivates beneficial lifestyle changes.²⁶

The flip side is also meaningful. A zero score, while medically reassuring, appears to decrease the motivation to take prescribed medications. That’s rational when the medication wasn’t clearly needed in the first place, but it can become a problem if someone uses a zero score to justify ignoring risk factors that the test doesn’t capture.

Calcium Spotted on Chest CTs Done for Other Reasons

You might learn about coronary calcium without ever ordering a dedicated CAC scan. If you’ve had a regular chest CT for any reason, such as a lung screening or a scan after a respiratory infection, the radiologist can often see coronary calcium on those images. One study found coronary calcification present in 68% of non-cardiac chest CTs, but it went unmentioned in the report about a third of the time.²⁷ A meta-analysis of the prognostic value of incidentally detected calcium found that its presence on routine chest CT was associated with substantially higher cardiovascular mortality.²⁸

If you’ve had a chest CT and the report doesn’t mention coronary calcium one way or another, it’s worth asking your doctor whether it was evaluated. An incidental finding on a scan you’ve already had is free additional information, and it might prompt a conversation about cardiovascular prevention you wouldn’t have had otherwise. The quantification isn’t as precise as a dedicated gated cardiac CT, but even a qualitative “calcium present” or “calcium absent” observation carries useful prognostic value.