Learn If You Should Have a Coronary Calcium Scan

Has your healthcare provider recommended that you get a coronary calcium scan? You may wonder if it is necessary if you have other cardiac risk factors but your stress test doesn't show a cardiac problem.

The general rule for taking any medical test is whether the results will be useful in making a decision about your medical care. In your case, your healthcare provider might use the results of the calcium scan to decide whether to prescribe statin therapy. Learn more about the calcium scan and how it is used.

CT scan being conducted

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What the Calcium Scan Tells You About Your Heart

A coronary calcium scan is a specialized computed tomography (CT) scan that detects calcium deposits in the coronary arteries (the arteries that supply blood to your heart muscle). Calcium deposits are part of atherosclerotic plaques. Therefore, the presence of calcium deposits means that the disease process of atherosclerosis is present.

The reason atherosclerotic plaques are important is that these plaques tend to rupture. Plaque rupture is often accompanied by the sudden formation of blood clots in the artery at the site of the rupture, leading to sudden occlusion (blocking) of the artery. This event is called acute coronary syndrome (ACS). ACS most often causes at least unstable angina (lack of blood flow causing chest discomfort) or, worse, myocardial infarction (heart attack).

If you have calcium in your coronary arteries, you already have atherosclerosis and you are at risk for ACS.

Calcium Score

A coronary calcium scan not only tells you whether you have calcium deposits, but it also measures the extent of the calcium deposits and reveals which of the coronary arteries are involved.

This information is summarized in a calcium score, which gives the following indications:

  • 0: No identifiable disease
  • 1–99: Mild disease
  • 100–399: Moderate disease
  • 400 or higher: Severe disease

The higher the calcium score, the more atherosclerosis is present in the coronary arteries and the higher the risk of experiencing ACS over the next several years. But, importantly, any score higher than zero means that atherosclerosis is already present and, at least to some extent, is active.

What the Calcium Score Really Means

When coronary calcium scans were first marketed in the early 2000s, they were surrounded by controversy. The controversy was mostly related to the fact that, at the time, the usefulness of these scans was poorly understood.

At that time, most cardiologists were only interested in atherosclerotic plaques that were large enough to cause significant obstruction in the coronary arteries. And the calcium scans are not particularly good at identifying which plaques cause the “50% blockages” that, it was thought, should be treated with stents (thin tubes inserted to open clogged arteries). The stress test was regarded back then as a far better screening tool for such so-called significant blockages.

Since that time, medical researchers have learned a lot about plaque rupture. It turns out that most cases of ACS occur with the rupture of “nonsignificant” plaques—plaques that were not causing significant blockage, and would not have been candidates for stenting.

This means two things. First, while stenting significant blockages may relieve any angina being produced by those blockages, it often does not greatly reduce the risk of subsequent heart attacks. Second, it turns out that long-term cardiac risk is more closely related to the overall “plaque burden” (that is, the number and extent of plaques of any size in the coronary arteries) than it is to the presence or absence of specific “significant” plaques.

Arguably, another name for plaque burden is the calcium score. Indeed, studies have now clearly shown that the higher the calcium score, the higher the subsequent cardiac risk, regardless of whether any of the plaques themselves are causing significant blockages.

What to Do About a Positive Calcium Scan

To summarize, the calcium scan tells you if you have atherosclerosis in the coronary arteries and, if so, the extent of atherosclerosis. If the calcium score is higher than zero (which, again, means that at least some atherosclerosis is present), some cardiologists will still recommend a stress test, which will help them decide whether any of the plaques are causing significant blockages. But this is not really the main point anymore.

The main point is whether you have atherosclerotic plaques. If you do—if your calcium score is higher than zero—it becomes very important to do everything you can to reduce your risk not only of developing further plaques but also of having a plaque rupture.

Obviously, lifestyle choices that help prevent the progression of atherosclerosis would then become critical. Weight control, getting plenty of exercise, not smoking, and controlling blood pressure and cholesterol levels all are even more important if you have atherosclerotic plaques.

Statins, drugs typically used to lower cholesterol, also become useful if your calcium scan is positive—even if your cholesterol levels are not elevated. This is because statins help to stabilize plaques and help to prevent them from rupturing. This, and not their ability to reduce cholesterol, now appears to be the chief way that statins reduce cardiac risk. Taking low-dose aspirin every day, under your healthcare provider’s guidance, may also be helpful if your calcium scan is positive.

A Word From Verywell

If your healthcare provider is recommending a coronary calcium scan, you should very seriously consider having it done. It can provide information that will help guide your therapy to reduce your risk of serious cardiac disease.

4 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Richard N. Fogoros, MD
Richard N. Fogoros, MD, is a retired professor of medicine and board-certified in internal medicine, clinical cardiology, and clinical electrophysiology.