A calcium score test is a quick, non-invasive CT scan that measures the amount of calcified plaque in your coronary arteries. The result is a single number that estimates your risk of having a heart attack or other cardiovascular event in the next decade. It takes about 10 minutes, requires no contrast dye or needles, and typically costs around $150 out of pocket.
What the Test Actually Measures
Your coronary arteries supply blood to your heart muscle. Over time, cholesterol-rich plaque can build up along their walls, and some of that plaque hardens with calcium deposits. A calcium score test uses a specialized CT scanner to take rapid X-ray images of your heart and detect those calcium deposits. The scanner captures images between heartbeats, so you don’t need to do anything except lie still and briefly hold your breath.
The result is called an Agatston score, calculated from the total area and density of the calcium found. A higher score means more calcified plaque, which signals more advanced coronary artery disease. It’s worth noting that the test only detects hard, calcified plaque. Softer plaque that hasn’t yet calcified won’t show up, which is why a score of zero doesn’t guarantee perfectly clean arteries, though it does indicate very low near-term risk.
What the Scores Mean
Your Agatston score falls into one of four general tiers, each associated with a different level of cardiovascular risk:
- 0: No detectable calcium. This places you in a low-risk category. For many people, a zero score is reason to hold off on starting a statin or aspirin, even if other risk calculators suggest borderline concern.
- 1 to 100: Mild plaque buildup. Your relative risk of a cardiac event is roughly double that of someone with a score of zero.
- 101 to 400: Moderate plaque buildup. Risk jumps to about four times that of a zero score.
- Greater than 400: Extensive plaque. Your relative risk is approximately seven times higher. Scores in this range typically lead to more aggressive treatment with cholesterol-lowering medication and closer monitoring.
Data from the Multi-Ethnic Study of Atherosclerosis, a long-running study that followed thousands of adults over a decade, found that for every doubling of a person’s calcium score, cardiovascular risk increased by 14 to 20 percent regardless of age, sex, or ethnicity. That consistent relationship is part of what makes the score useful across diverse populations.
Who Should Get One
The test is most valuable for people sitting in a gray zone of cardiovascular risk, specifically those with a 10-year risk estimated between 5 and 20 percent using standard risk calculators. In that intermediate range, doctors and patients often face a tough call about whether to start preventive medications like statins. A calcium score can tip the decision in either direction: a score of zero may justify waiting, while a score of 100 or higher strengthens the case for treatment.
Current clinical guidelines consider the test medically appropriate for adults between 40 and 75 who have no known heart disease, are not diabetic, and have LDL cholesterol between 70 and 190 mg/dL. If you already have strong risk factors on their own, like a family history of early heart disease, very high LDL, metabolic syndrome, or chronic kidney disease, the test adds less information because aggressive treatment is already warranted regardless of the score.
The scan is not designed for people who are already having symptoms like chest pain or shortness of breath. Those patients need diagnostic testing that can visualize active blockages, not just calcium deposits.
How the Test Works in Practice
You’ll be asked to avoid food, drinks, caffeine, and tobacco for four hours beforehand. No IV line is placed and no contrast dye is injected, which sets this apart from more involved cardiac imaging. You lie on a table that slides into a CT scanner, and electrodes are placed on your chest to sync the images with your heartbeat. The actual scanning portion takes only a few minutes. Most people are in and out of the facility within 30 minutes total.
Radiation exposure is low, around 1 to 2 millisieverts. For comparison, a standard chest X-ray delivers about 0.05 millisieverts, so a calcium scan is equivalent to roughly 20 to 40 chest X-rays. That’s a modest dose, well below the threshold that raises concern, but it’s one reason the test isn’t recommended as routine screening for everyone.
Cost and Insurance Coverage
Most calcium score tests cost around $150, and most insurance plans do not cover them because the scan is considered preventive rather than diagnostic. Some hospitals and imaging centers offer it at a discounted cash price specifically because it’s a common self-pay test. If your doctor recommends it to guide a medication decision, it’s worth calling your insurer to check, but plan on paying out of pocket.
How It Differs From Other Heart Scans
A calcium score test is sometimes confused with a coronary CT angiography, but the two serve different purposes. A CT angiography uses contrast dye injected through an IV to create detailed images of your arteries, revealing both calcified and soft plaque as well as active narrowing. It involves more radiation and is typically ordered when someone is already experiencing symptoms. A calcium score scan, by contrast, is a screening tool for people without symptoms, designed to catch disease before it causes problems.
Traditional coronary angiography, performed through a catheter threaded into the arteries, is even more invasive and reserved for cases where blockages need to be directly measured or treated. The calcium score sits at the least invasive end of the spectrum, providing a useful first look at arterial health with minimal risk and hassle.
What Happens After Your Results
A score of zero is reassuring, and for many patients it means revisiting the question in five to ten years rather than starting medication now. Scores between 1 and 99 open a conversation about lifestyle changes, including diet, exercise, and blood pressure management, with medication as a possibility depending on other risk factors. Once your score crosses 100, most clinicians will recommend statin therapy along with closer attention to blood pressure and blood sugar. Scores above 400 often prompt additional testing to check for significant blockages.
Your calcium score only goes up over time. Calcium in the arteries doesn’t dissolve, even with treatment. The goal of medication and lifestyle changes isn’t to lower the number but to slow plaque progression and stabilize existing deposits so they’re less likely to rupture and cause a heart attack. For that reason, repeating the scan every few years to track the rate of change can sometimes be more informative than any single result.