Cardiac CT angiography produces a detailed picture of the coronary arteries using a CT scanner and an injection of contrast into a vein in the arm. It shows whether there are narrowings in the arteries, and how much calcium and plaque is present in the artery walls.

It has become a first-line test for many people with chest pain because it looks directly at the arteries rather than inferring their state from how the heart behaves under stress.

The scan itself takes only a few seconds, though the appointment is longer. A medication to slow the heart rate is often given beforehand, because a slower, steadier heart rate produces clearer images.

What to expect

You may be asked not to eat for a few hours beforehand, and to avoid caffeine on the day.
A cannula is placed in a vein in your arm for the contrast injection.
Medication to slow the heart rate is commonly given, either as a tablet beforehand or through the cannula.
The contrast injection often causes a brief warm sensation. This is expected and passes quickly.
Cardiac CT involves exposure to X-rays. Whether it is the right test for you is part of the consultation.