CT Coronary Angiography
CT coronary angiography is undertaken to assess the state of a patient's coronary arteries. The test uses a computerised tomography (CT) scanner to take X-ray images of the heart and specifically the coronary arteries.

The test is usually consists of 2 parts; the first is a "Calcium Score", and the second is the angiogram itself.
CT calcium score

This is a quick scan through the heart to assess the build-up of calcium around the coronary arteries. Calcium in the walls of the coronary arteries is a sign of long standing, but often very mild, coronary artery disease.

The calcium score gives us excellent prognostic data (and therefore helps guide treatment). In addition it helps guide the quality of the angiogram; if there is a large build up of calcium, the angiogram will most likely be unhelpful and therefore your doctor may choose to offer an alternative test.
CT coronary angiography

The angiography requires injection of a contrast dye, which is then imaged as it passes down the coronary arteries. This is often felt by the patient as a hot flush, as the contrast feels warm as it is injected.

For the best images, the cardiologist may choose to give you a drug to slow the heart beat down. A nice slow steady heart beat means that the images are clearer, and the team can use settings so that they use less radiation to record the scan. The drug usually used is a beta-blocker (metoprolol), but other treatments are available if a patient has had problems with beta blockers in the past.
After the CT coronary angiogram

A CT scan is an incredibly complex investigation, and it takes some time for the team (usually a cardiologist and a radiologist) to review all the images and report the scan. The cardiologist who is present at the time of the scan should be able to give you a very brief report immediately, but you will get the full result in the week or so following the scan.

After the scan itself, you are usually asked to stay in the department for around 30 minutes to ensure you have no reaction to the test, and then you are free to go (ensuring the little cannula used for the contrast has been removed first!). You may feel slightly lightheaded immediately afterwards, especially if you were given some beta blockers, but otherwise you should be fine to return to a normal day. We normally ask you drink plenty of water to help flush the contrast out of your system; the cardiologist present may suggest otherwise to you if you have a reason for fluid restriction.