A coronary artery calcium scan, often called a CAC score or calcium score, is a quick CT scan of the heart that looks for calcified plaque in the coronary arteries. It has become a popular test among people who want a clearer picture of their heart risk, and it can be genuinely useful. It is not a test everyone needs.

What the scan shows

Calcium in the walls of the coronary arteries is a marker of atherosclerosis, the plaque that causes most heart attacks. The scan adds up the calcium it finds into a single number. RadiologyInfo, the patient site of the American College of Radiology and the Radiological Society of North America, describes the usual ranges: a score of 0 shows no evidence of coronary artery disease, 1 to 10 minimal, 11 to 100 mild, 101 to 400 moderate, and over 400 extensive.

According to RadiologyInfo, the exam takes less than 20 minutes and does not require an injection of contrast material. It does use x-rays, and the radiation dose varies. It does not show soft plaque that has not calcified, and it does not show whether an artery is narrowed enough to limit blood flow.

Where it fits in a risk assessment

Doctors usually start with a 10-year risk estimate built from age, sex, blood pressure, cholesterol, diabetes and smoking, as described in the 2019 prevention guideline. The guideline then adds risk-enhancing factors, such as family history, kidney disease, early menopause and certain lab results, to refine that estimate. A calcium score is one more piece of information on top of these, not a replacement for them.

Who it helps

The calcium score is most useful when a treatment decision is genuinely uncertain. The 2018 cholesterol guideline from the American Heart Association, American College of Cardiology and other groups suggests considering it for adults whose estimated 10-year heart risk is in the intermediate range, and for some at borderline risk, when it is unclear whether to start a statin. The 2019 primary prevention guideline takes the same approach.

In that setting, the guideline describes how the score can shift the decision:

  • A score of zero may make it reasonable to hold off on a statin and reassess in five to ten years, unless other high-risk features are present, such as diabetes, current smoking or a strong family history of early heart disease.
  • A score of 1 to 99 generally favors a statin for people 55 and older.
  • A score of 100 or higher, or at or above the 75th percentile for age and sex, generally favors a statin.

RadiologyInfo summarizes it the same way: a score of zero may support delaying cholesterol medicine in some people, while a high score may support starting it.

Who it helps less

  • People who already have heart disease, such as a prior heart attack, stent or bypass. Their treatment is already clear.
  • People with symptoms such as chest pain or breathlessness with exertion. They need a different evaluation, not a screening scan.
  • People at very low risk, where a result is unlikely to change anything and may lead to further testing.
  • People already certain to take, or decline, a statin regardless of the result.

The US Preventive Services Task Force concluded in 2018 that the evidence was insufficient to judge the benefits and harms of adding a calcium score to standard risk assessment in adults without symptoms, and notes that an update on calcium scoring is in progress. That is a statement about population screening. It sits alongside the cardiology guidelines that use the score for selected individuals.

What to think about before you book one

Calcium scans are sometimes offered directly to consumers. The scan itself is simple, but the result raises questions: what to do with a moderate score, whether a finding outside the heart on the image needs follow-up, and how the number fits with cholesterol, blood pressure, family history and Lp(a). Insurance coverage varies, so ask your plan before you schedule.

It also helps to know the rest of your numbers first. Our articles on ApoB and lipoprotein(a) and menopause and heart health cover other factors that can tip a borderline decision. The USPSTF’s separate guidance on statin use for prevention explains how risk estimates are used.

How Dr. Shtern approaches it

The useful question is not whether a calcium score is a good test, but whether it would change your plan. Dr. Shtern can estimate your risk with your labs and history, explain where you fall, and help you decide whether a scan would settle anything. If it would, she can order it and go through the result with you.

Blood pressure and cholesterol are part of her everyday work, along with the kidney health that often travels with them. Read more about hypertension care at Legacy Medical, or book a complimentary meet and greet to talk about your own heart risk.

This article is general information, not advice for your situation. Members can call the office with questions about their own care.