What is coronary CTA?

Coronary computed tomography angiography (CCTA) is a heart imaging test that helps determine if plaque buildup has narrowed the coronary arteries, the blood vessels that supply the heart. Plaque is made of various substances such as fat, cholesterol and calcium that deposit along the inner lining of the arteries. Plaque, which builds up over time, can reduce or in some cases completely block blood flow. Patients undergoing a CCTA scan receive an iodine-containing contrast material as an intravenous (IV) injection to ensure the best possible images of the heart blood vessels.

Computed tomography, more commonly known as a CT or CAT scan, is a diagnostic medical imaging test. Like traditional x-rays, it produces multiple images or pictures of the inside of the body.

A CT scan generates images that can be reformatted in multiple planes. It can even generate three-dimensional images. Your doctor can review these images on a computer monitor, print them on film or via a 3D printer, or transfer them to a CD or DVD.

CT images of internal organs, bones, soft tissue, and blood vessels provide greater detail than traditional x-rays. This is especially true for soft tissues and blood vessels.

What are some common uses of the procedure?

Many physicians advocate the careful use of CCTA for patients who have:

• suspected abnormal anatomy of the coronary arteries.
• low or intermediate risk for coronary artery disease, including patients who have chest pain and normal, non-diagnostic or unclear lab and ECG results.
• low to intermediate risk atypical chest pain in the emergency department.
• non-acute chest pain.
• new or worsening symptoms with a previous normal stress test result.
• unclear or inconclusive stress test results.
• new onset heart failure with reduced heart function and low or medium risk for coronary artery disease.
• intermediate risk of coronary artery disease before non-coronary cardiac surgery.
• coronary artery bypass grafts.

For patients meeting the above indications, CCTA can provide important information about the presence and extent of plaque in the coronary arteries. Apart from identifying coronary artery narrowing as the cause of chest discomfort, it can also detect other possible causes of symptoms, such as a collapsed lung, blood clot in the vessels leading to the lungs, or aortic abnormalities. Your primary care physician or cardiac specialist, in consultation with a radiologist who would perform the test, will determine whether CCTA is appropriate for you.

Who interprets the results and how do I get them?

A radiologist, a doctor specially trained to supervise and interpret radiology exams, will analyze the images. The radiologist will send an official report to the doctor who ordered the exam.

If you are actively having chest pain, your results will be given to the emergency room doctor by the radiologist, and a preliminary result will be reported right away.

You may need a follow-up exam. If so, your doctor will explain why. Sometimes a follow-up exam further evaluates a potential issue with more views or a special imaging technique. It may also see if there has been any change in an issue over time. Follow-up exams are often the best way to see if treatment is working or if a problem needs attention.

What are the benefits vs. risks?

Benefits

• CCTA is not invasive. An alternative test, cardiac catheterization with a coronary angiogram, is invasive, has more complications related to the placement of a long catheter into the groin or wrist arteries extending all the way to the heart, and the movement of the catheter in the blood vessels. Invasive catheterization requires more time for the patient to recover.
• A major advantage of CT is that it is able to view bone, soft tissue and blood vessels all at the same time. It is therefore suited to identify other reasons for your discomfort such as an injury to the aorta or a blood clot in the lungs.
• Unlike conventional x-rays, CT scanning provides very detailed images of many types of tissue.
• CT examinations are fast and simple.
• CT has been shown to be cost-effective for a wide range of medical problems.
• CT is less sensitive to patient movement than MRI.
• Unlike MRI, an implanted medical device of any kind will not prevent you from having a CT scan.
• No radiation remains in a patient's body after a CT exam.
• The x-rays used for CT scanning should have no immediate side effects.

Risks

• In some people with abnormal kidney function, the contrast material used in CT scanning may worsen kidney function.
• If contrast material leaks out from the vessel being injected and spreads under the skin where the IV is placed, skin damage or damage to blood vessels and nerves, though unlikely, can result. If you feel any pain in your arm at the location of the IV during contrast material injection, you should immediately inform the technologist.
• There is always a slight chance of cancer from excessive exposure to radiation. However, the benefit of an accurate diagnosis far outweighs the risk involved with CT scanning.
• The radiation dose for this procedure varies. See the Radiation Dose page for more information.
• Women should always tell their doctor and x-ray or CT technologist if there is any chance they are pregnant. See the Radiation Safety page for more information about pregnancy and x-rays.
• Doctors do not generally recommend CT scanning for pregnant women unless medically necessary because of potential risk to the unborn baby.
• IV contrast manufacturers indicate mothers should not breastfeed their babies for 24-48 hours after contrast material is given. However, the most recent American College of Radiology (ACR) Manual on Contrast Media reports that studies show the amount of contrast absorbed by the infant during breastfeeding is extremely low. For further information please consult the ACR Manual on Contrast Media and its references.
• The risk of serious allergic reaction to contrast materials that contain iodine is rare, and radiology departments are well-equipped to deal with them.

What are the limitations of coronary CTA?

A person who is very large may not fit into the opening of a conventional CT scanner. Or, they may be over the weight limit—usually 450 pounds—for the moving table.

Patients who are extremely overweight or who have abnormal heart rhythms may not be good candidates for this test because image quality may be compromised.

Unlike CCTA, which is only a diagnostic test, invasive coronary angiography can be used for both diagnosis and treatment in a single session. If a narrowing or blockage is found during a CCTA, it cannot be treated at the same time. Patients with a high risk of coronary artery disease and typical symptoms might undergo coronary angiography instead of CCTA because they are more likely to need treatment.

CCTA can be difficult to read if there are many areas of old, calcified (hardened) plaque, which can be the case in older patients.