​The Cardiac Computed Tomography (CT) scan is a non-invasive (no incision required) test which examines the coronary arteries, vessels that supply oxygenated blood to the heart wall.

Plaque is a buildup of fats and other substances including calcium, which can narrow the arteries or even close off blood flow to the heart over time. This may result in chest pain or heart attack.

Cardiac CT is a relatively painless scan which allows physicians to obtain information about the location and the extent of calcified plaque in the coronary arteries with a greater degree of accuracy.

Before Cardiac CT is made available, the only way to assess the degree of narrowing in the coronary arteries was via an invasive (incision required) coronary angiogram which requires the patient to stay in the hospital for a day.

Is the test safe?

The risks of a cardiac CT scan include radiation exposure, allergic reactions to the contrast and contrast leaking into the skin. These are rare and have an occurrence rate of less 1%.

Alternative tests

The Stress MIBI or Stress Echo is also a non-invasive way of examining the health of the coronary arteries.

Before the scan

Metal objects including jewellery, spectacles, dentures and hairpins may affect the CT images and should be left at home or removed before your scan. You may also be asked to remove your hearing aids.
Before the start of the scan, you will be taught to hold your breath for about 10-15 seconds during the scan.

Dos and Don'ts

Things to do before your scan:

Dos

1. Do drink 2 glasses of water 2 hours before your appointment
2. Do continue with any medication that you usually take, except for metformin*.
3. Do wear clothing that can be removed easily because you will need to change into hospital gown for your scan.

Don’ts

1. Do not take any caffeinated beverages such as coca cola, coffee or tea on the day of the scan.
2. Do not eat any food or smoke for 4 hours before your appointment time.
3. Do not use Viagra, Cialis or Levitra for 48 hours before and after the scan.

During the scan

The medical technologist begins by positioning you on the CT examination table, usually flat on your back. ECG leads will be attached to your chest to monitor your heartbeat. Straps and pillows may be used to help you maintain the correct position and to hold still during the scan. The medical technologist will give you instructions on when to breathe in and hold your breath for 10-15 seconds. You may also feel a little warm upon injection of the contrast. This should subside after a short while. The actual scanning will be completed within a few minutes and the images will be processed and read. Results will then be sent to your doctor.

Note:

• If you are diabetic and taking metformin (Glucophage®), you must discontinue the use of metformin at the time of or before the scan, and to refrain from taking metformin for 48 hours after the scan.
• If your heart rate is 90 beats a minutes or higher, you may be given a drug to slow the rate in order to obtain accurate images.
• If you have asthma and/or drug allergies, you may be prescribed medicine before the test.
  Before the scan, an intravenous catheter (a small plastic tube) will be inserted in your arm for intravenous contrast injection. If you have a previous contrast reaction (eg allergy), please inform the attending physician.