A heart computed tomography (CT) scan uses X-rays to create detailed images of your heart. The test can help doctors evaluate the structure and function of the heart and the surrounding blood vessels.

A heart CT scan may also be called a cardiac CT angiography (CCTA) scan if your doctor injects contrast dye to make your coronary arteries more visible on the X-ray images.

Your doctor may also obtain a calcium score during the scan, which measures the amount of calcium in the blood vessels. Calcium buildups may contribute to blockages.

A heart CT scan uses noninvasive X-rays to create detailed 3D pictures of your heart. These images can help your doctor identify heart conditions.

During the scan, a radiology technologist or nurse may inject a specialized dye called contrast dye to help evaluate your heart and blood vessels. The dye can highlight blockages, narrowing of the arteries, and issues with the heart’s pumping.

You may also receive medications to slow your heart rate and widen your blood vessels, which can make them easier to see in the images.

Your doctor will place small patches called electrodes on your chest so they can take images when your heart is as still as possible, making them clearer.

A heart CT scan allows your doctor to evaluate the heart and the structures surrounding it without making any incisions. Your doctor may order a heart CT scan to check for plaque in your arteries.

They may also recommend the scan to further investigate unusual results from other tests or to check how well other procedures, like bypass grafting, worked.

Heart CT scans may show evidence of various heart conditions, including:

Before the day of your scan, tell your doctor about any medications, vitamins, or supplements you take. You may need to stop taking them for a period of time before the test.

Your doctor may ask you to avoid eating for at least 4 hours before your scan begins. You may be able to drink water or other clear liquids that don’t contain caffeine, but ask your doctor for specific instructions.

Wear comfortable clothing on the day of your scan. At the facility, you’ll need to remove any jewelry and metal items from your body, such as piercings and clothing with zippers or snaps. Your care team will give you a hospital gown to wear.

A CT technologist or nurse will insert an intravenous (IV) line into one of your veins to prepare you for the scan.

This line may administer medications to widen your blood vessels and slow your heart rate, which can make blockages easier to see on the X-ray images. The IV line can also deliver the contrast dye.

A note about contrast dye

Some people shouldn’t receive contrast dye. Discuss your medical history with your doctor before the test, and be sure to mention if you’ve ever had an allergic reaction to contrast dye or if you’re pregnant or may become pregnant.

In rare instances, the contrast dye can cause severe kidney issues, particularly in people with existing kidney disease or other conditions. Talk with your doctor about any conditions you have.

Learn more about contrast induced nephropathy.

A cardiac CT scan usually takes place in a hospital or a specialized diagnostic clinic. For the procedure, a radiology technician places electrodes on your chest that connect to an electrocardiogram machine. This allows your care team to monitor your heart’s electrical activity.

If your doctor decides to do the scan with contrast, a technician will inject the dye into your IV, which might cause a warm sensation.

At the start of the procedure, you’ll lie down on the scanner’s bench before it moves into the CT machine, which may look like a large tube or ring.

The benchtop moves in and out of the scanner’s opening to obtain different views of the heart. During the procedure, stay as still as possible to prevent blurry images.

After a few rounds of scans, your CT technician will review the images for clarity. The procedure may be as short as 15 minutes, but it may take longer in some cases.

After your heart CT scan, you may be able to return to your usual routine without restrictions unless your doctor gives you other instructions. They may recommend drinking plenty of water to flush the dye out of your body.

Many people can drive themselves home after the scan. However, if you received additional medications for an allergy to the contrast dye or a sedative, you will need someone else to drive you.

A radiologist will review the images from the scan, and your doctor will discuss any findings at your next appointment.

Results from a heart CT scan may reveal:

  • issues with the heart’s valve function or pumping ability
  • calcium buildup
  • blockages
  • coronary artery disease
  • structural heart disease
  • other heart conditions

Depending on what the scan images show, your doctor may order follow-up tests, such as an exercise stress test or cardiac catheterization.

If your doctor has enough information to diagnose a heart condition, they may create a treatment plan that involves lifestyle changes, medications, or additional procedures.

A heart CT scan is typically a safe procedure, but there may be a few potential risks.

Radiation exposure

A heart CT scan uses radiation. It exposes you to more radiation than a standard X-ray, but the level of radiation is still relatively low.

If you’re pregnant or may become pregnant, talk with your doctor about any possible pregnancy-related risks and whether you have any alternative testing options.

Contrast dye

The contrast dye used in heart CT scans can contain iodine, which is flushed from the body through the kidneys. If you have a condition that affects your kidneys, ask your doctor whether a CT scan with dye is safe for you.

Some people may also experience mild to severe side effects from contrast dyes. Tell your doctor right away if you experience any of the following symptoms:

  • itching and skin flushing
  • skin rash or hives
  • difficulty breathing

If you’ve previously had an adverse reaction to contrast dye, you may have a higher risk of an allergic or adverse reaction in the future.

If you believe you’re at risk of a reaction, speak with your doctor about treatments to manage reactions or possible alternatives to CT scans.

Heart CT scans are noninvasive procedures that can help doctors evaluate the heart’s structure, function, and blood flow. Healthcare professionals may use CT scans to help diagnose heart conditions like coronary artery disease or valve issues.

Though CT scans are typically safe, they may not be right for everyone. Your doctor needs a thorough understanding of your health status and history to decide whether a CT scan is your best testing option.