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What is a cardiac CT scan?

A cardiac CT angiography (CCTA) scan is a noninvasive test that uses X-rays to take images of your heart and blood vessels. A computer combines the images to create a three-dimensional (3D) image of your heart.

A CCTA scan is used to help find the presence of and percent of narrowing (stenosis) in the coronary arteries and blood vessels that supply blood to the heart or other parts of the body.

Multidetector CT, or MDCT, scans work fast and are very detailed. They can produce better images with lower radiation exposure.

Why do people have a CCTA scan?

You may need a CCTA scan when other tests, such as a chest X-ray, electrocardiogram (ECG), echocardiogram (echo), or stress test, don’t give your health care team enough information about your heart.

The test can help your health care team gather additional information on:

• Your heart’s structure and how well your heart pumps blood.
• Scarring of the heart muscle caused by a heart attack. 
• Fluid in the pericardial sac that covers the surface of the heart.
• The amount of plaque buildup and narrowing of your coronary arteries.
• Any abnormalities in the large blood vessels leaving the heart.
• Your risk for a heart attack.

Can it help show if you have heart disease?

When contrast dye (iodine) is given during the CCTA scan, it can show blockages in your heart arteries. This is useful to see if chest discomfort comes from lack of blood flow to the heart muscle due to blocked heart arteries (angina). If the heart arteries are normal, your health care team can confidently look into other causes of chest pain that aren’t related to the heart.

With contrast dye, the CCTA scan can also check if coronary artery bypass grafts remain open following heart bypass surgery or detect congenital heart defects (problems present at birth) and how your ventricles are working. 

Can I have a CCTA scan instead of a coronary angiogram?

CCTA scan is not a substitute for a coronary angiogram (PDF) or cardiac catheterization. Coronary angiography is the gold standard method for showing blockages in the coronary arteries. It also gives specific information about how your heart is working. In some cases, a CCTA may be done instead of a coronary angiogram. This is based on patient factors as well as the imaging capabilities of the hospital or outpatient center.

What are the risks?

A CCTA scan exposes you to radiation. Further studies on safety and possible risks are warranted. Talk with your health care team about safety and risks for any test you’re undergoing.

Tell your health care team if you’re pregnant. If the test is not urgent, ask them about delaying it until after your pregnancy. Also, if you have kidney problems, you may not be able to receive contrast dye. Your health care team will measure your kidney function before the test and may give you medications to help protect your kidneys from potential damage.

Some people have allergic reactions to the contrast dye that’s sometimes used in the test. Before the test, tell your health care professional if you’re allergic to dyes, iodine or shellfish.  Depending on the type of reaction you have previously had, certain medications like antihistamines and steroids may be given before the test to greatly reduce the chance of an allergic reaction. In the case of a severe allergic reaction, contrast dye will not be used and instead a test that doesn’t require contrast may be used.

How do I prepare for the CCTA scan?

Talk to your health care professional about how long to fast before the test.

What happens during the test?

Technicians perform the CCTA scan in hospitals or special outpatient clinics.

• Electrodes will be attached to your chest to monitor your ECG. The ECG also helps the computer connected to the CT scanner create clear pictures of your heart.
• When you're ready, the table slowly moves inside the machine. The scanner arches around you but doesn’t touch you.
• If a contrast dye is used, it's injected through an intravenous line placed in an arm vein.
• You may also be given medicines that widen your heart arteries or slow down your heartbeat. These medicines make it easier to see any blockages in the heart arteries.
• The technician will watch you closely through a window. You can talk to him or her through a two-way intercom.
• The technician will ask you to hold your breath for short periods.
• CT scanning takes about 5-10 minutes.

What happens after the CCTA scan?

• Your health care professional will let you know when to resume normal activities.
• After the health care team gets a written report of the test results, they will make an appointment to discuss the results and next steps with you.