A heart scan, also known as a coronary calcium scan, is a specialized X-ray test that provides pictures of your heart that can help your doctor detect and measure calcium-containing plaque in your arteries.

Plaque inside the arteries of your heart can grow and restrict blood flow to the muscles of your heart. Measuring calcified plaque with a heart scan may allow your doctor to identify possible coronary artery disease before you have signs and symptoms.

Your doctor will use your test results to determine what you need — medication or lifestyle changes — to reduce your risk of a heart attack or other heart problems.

Your doctor may order a heart scan to get a better understanding of your risk of heart disease or if your treatment plan is uncertain.

A heart scan uses a specialized X-ray technology called multidetector row or multislice computerized tomography (CT). The scan creates multiple images that can show any plaque deposits in the blood vessels. A heart scan provides an early look at levels of plaque.

Plaque is made up of fats, cholesterol, calcium and other substances in the blood. It develops gradually over time, long before there are any signs or symptoms of disease. These deposits can restrict the flow of oxygen-rich blood to the muscles of the heart. Plaque may also burst, triggering a blood clot that can cause a heart attack.

When is a heart scan used?

A heart scan may help guide treatment if you have a low to moderate risk of heart disease or if your heart disease risk isn't clear. Your doctor can tell you if you might benefit from having a heart scan based on your risk factors.

A heart scan may also help motivate people at moderate risk to make important lifestyle changes and follow treatment plans.

Heart scans use X-ray technology, which exposes you to radiation. The amount of exposure is generally considered safe — about the same amount of radiation you're naturally exposed to in a year.

Some medical facilities and walk-in centers advertise heart scans as an easy way to measure your risk of a heart attack. These scans don't require a referral from a doctor and might not be covered by your insurance. Also, there are less expensive blood tests and blood pressure monitoring that might offer similar information.

When scheduling your heart scan appointment, ask these questions:

• Are there any special instructions?
• How early should I arrive?
• What paperwork or identification will I need?

Food and medications

You may be asked to avoid caffeine and smoking for four hours before the test.

Clothing and personal items

When you arrive for the procedure, you will be asked to remove clothing above the waist and to wear a medical gown. You will also need to remove jewelry around your neck or near your chest.

During the procedure

Before the scan begins, the technician attaches sensors, called electrodes, to your chest. These connect to a device that records your heart activity during the exam and coordinates the timing of X-ray pictures between heartbeats, when the heart muscles are relaxed.

During the heart scan, you lie on your back on a movable table, which slides into the tubelike CT scanner. Your head is outside the scanner the whole time. The exam room will likely be cool.

You may be given medication either by pill or injection that slows your heart. This helps ensure clear images. If you are nervous or anxious, you may be given medication to help you remain calm.

You'll be asked to lie still and hold your breath for a few seconds while the pictures are taken. The technician operates the scanner from a room next door, but can see and talk to you the entire time. The entire procedure should take about 10 to 15 minutes.

After the procedure

Usually, no special precautions are needed after having a heart scan. You should be able to drive yourself home and continue your daily activities.

The result of the test is usually given as a number called an Agatston score. The score reflects the total area of calcium deposits and the density of the calcium.

• A score of zero means no calcium is seen in the heart. It suggests a low chance of developing a heart attack in the future.
• When calcium is present, the higher the score, the higher your risk of heart disease.
• A score of 100 to 300 means moderate plaque deposits. It's associated with a relatively high risk of a heart attack or other heart disease over the next three to five years.
• A score greater than 300 is a sign of very high to severe disease and heart attack risk.

You also may receive a percentile score, which indicates your amount of calcium compared to people of the same age and sex.

The result of a heart scan shouldn't be used as a single predictor of your overall health and risk of heart disease. The information from a heart scan should be combined with other health information.

Discussing results with your doctor

Your doctor will discuss the results of the heart scan with you. Depending on the outcome, one or more of the following strategies may be needed:

• No change to current treatment plan
• Different medication or dose of medication
• Changes to your diet and exercise routine
• New weight-loss goals
• Additional tests
• Follow-up appointments to monitor your health and treatment plan