Coronary Artery Calcium (CAC) Scoring

Coronary artery calcium (CAC) scoring – also called a coronary calcium scan – shows if calcium is present in the walls of the heart’s arteries and, if so, how much.

Most calcium in your body is found in bones and teeth to help keep them strong and healthy. But calcium in the arteries that supply the heart can signal trouble for your heart health.

Calcium in the coronary arteries often means plaque is building up. Plaque is a waxy substance that can harden and narrow or block the arteries (called atherosclerosis). This raises the chance (risk) of a heart attack or stroke. 

A coronary calcium scan is a simple imaging test that helps estimate someone’s risk for heart disease, heart attack or stroke – even before other signs or symptoms develop. In some ways, CAC scoring is similar to a bone density test. Just as bone density helps predict the likelihood of a hip fracture, CAC helps estimate heart disease risk.

Who Should Get a CAC Scan

A CAC test detects early (subclinical) calcium and plaque buildup. It is best used:

• If there is uncertainty about one’s true risk of heart disease and related events and

• To help decide if starting a statin is needed

CAC scoring is recommended for some:

• Men over age 40
• Women over age 45

  In particular, those who are at borderline or intermediate risk of having a heart attack or stroke in the next 10 years.

CAC scoring is not generally useful or helpful if you have:

• Low risk for heart disease (no risk factors) or
• High risk for heart disease or have heart disease already, or if you’ve already had a heart attack, stroke, stent or bypass surgery

CAC scoring doesn’t identify if an artery is blocked. It also shouldn’t be used to assess whether treatment is working or not.

What the Test Results Mean

The results are given as a number called a CAC score. This score reflects the amount of calcium (or calcified plaque) in the heart’s arteries. It ranges from 0 to over 400. Your clinician can help explain what your score means for your heart health. 

The more evidence of calcium in the inside lining of the arteries, the higher the score. The higher your CAC score, the more likely you are to develop heart disease or have an event such as a heart attack or stroke. 

Keep in mind, a CAC score is a tool to help estimate the chance of developing disease. It can’t predict exactly what will happen. So, people with a 0 score could still have a heart attack, but the risk is very low. Similarly, people with a high CAC score aren’t certain to have a heart attack. This is why CAC scoring should be used together with other methods for estimating heart disease. 

What to Expect

A coronary calcium scan is often done in a hospital or other medical imaging facility. 

The test:

• Is fairly quick (it takes about 10-20 minutes)
• Uses a low dose of radiation
• Doesn’t require contrast — a special dye that is injected in your vein that is needed for some other imaging tests 
• Often includes an electrocardiogram (ECG), too

Be sure to let your clinician know if you are or could be pregnant before having this test.