Overview

When you hear or read about a ‘heart scan’, more often than not, it refers to a CT scan of the heart. A CT scan, also called a ‘CAT scan’ or a ‘computed tomography scan’, is a scan which uses radiation (x-rays) to create images on a computer of areas inside the body. These can be 2D or 3D and are often very detailed.

A CT scan of the heart helps professionals diagnose heart problems and establish their severity in order to consider the appropriate treatment options. There are 2 types of CT scans for hearts: 

• CT Coronary Angiogram
• Coronary Calcification Scan

In this article, we will explore these two different types of scans, why they are useful and how they are performed. 

CT coronary angiogram

A CT coronary angiogram (also called Coronary CT Angiography) is a radiographic test meaning it uses radiation which enables healthcare professionals to get a direct view in 2D and 3D of different parts of the heart.¹

This includes: 

• The atria (upper chambers)
• The ventricles (lower chambers)
• The pericardium (the sac surrounding the heart)²
• The main cardiac vessels (arteries)
• The myocardium (the heart muscle) 
• The heart valves

Why have a CT coronary angiogram?

A patient will usually be referred for a CT Coronary Angiogram if they are having surgery soon which requires this scan in advance or if they are displaying symptoms of Coronary Artery Disease – or Coronary Heart Disease.

The symptoms may include, among other things: chest pain, neck/arm/back/jaw pain and breathlessness.³ 

Over time, fatty deposits can build up in a person’s coronary (heart’s) arteries. When there is too much plaque buildup in the arteries, they become narrow, meaning that the heart is not supplied with sufficient blood and oxygen, and this is referred to as coronary heart disease.

It is an extremely common cause of death around the world, and it requires swift diagnosis and treatment.³  These days, a CT coronary angiogram is the leading procedure for diagnosing coronary heart disease.⁴ 

When someone is undergoing a CT coronary angiogram, the main thing the radiographer will be looking at in the scan is the fatty deposits built up inside the arteries. The scan can  detect the amount of plaque in the arteries, and whether it is calcified (contains calcium) or non-calcified – as well as other signs that could affect the patient’s risk level.⁵ 

What happens in a CT coronary angiogram?

To have a CT coronary angiogram, you will usually have adhesive patches stuck to your chest first - called electrodes - which will connect to a monitor via leads. This monitor will allow the practitioner to see the electrical activity/rhythm of your heart. 

In some cases, where someone’s heart rate is faster than 60 beats per minute, they may be injected with a medication called a beta-blocker which will slow down the heart rate – this makes it safer for the patient. The effects of this procedure will be temporary and should not cause any inconvenience once it is completed. 

You may also be given glyceryl tablets to dissolve under your tongue which will help to widen (dilate) your arteries to show blockages more clearly. There may be mild, temporary side effects such as dizziness or headaches.

In order for the blood flowing through your arteries to show up on the scan, you will be given an infusion of a dye called contrast through a small vein in your arm. It may cause some short-lived side effects such as experiencing the taste of metal in your mouth,  

You will then have the scan which will not cause any pain. You will be asked to hold your breath ( not for more than 15 seconds) so that the radiographer can get clear pictures. 

Once you are finished, you may be asked to remain for a short period to ensure that you are feeling well.

You can find out more details on the NHS website here. 

What are the risks of a CT coronary angiogram?

A CT coronary angiogram is a largely safe procedure, however, as with many medical procedures, there are a few risks associated.  

During the scan, you will be exposed to radiation at a fairly high level. As a one-off, this is not a huge worry, but it can be harmful if you are consistently exposed to radiation.⁶

Another possible risk is having an allergic reaction to the dye, however, your practitioner will talk with you beforehand to try and assess whether you are at a high risk of this. 

Finally, on rare occasions the dye can leak from your veins and cause some swelling – this will not last very long and you will be advised on how to handle this. 

Coronary calcification scan

A coronary calcification scan is much simpler. Instead of detailed images of the heart and its arteries, it just allows for the measurement of calcified plaque in the arteries – calcified meaning that the plaque contains calcium and is hardened.

The result of this scan is usually given as a ‘calcium score’ which indicates how much fatty plaque a person has in their arteries. 

Why have a coronary calcification scan?

Patients may be referred for a coronary calcification scan if they have no symptoms associated with heart problems, but a better understanding is needed of their heart attack risk level and their need for certain medications. 

Sometimes this understanding can come from risk factors, but this is not foolproof and the calcium score calculated from a coronary calcification scan has been proven to be a successful way of predicting an asymptomatic person’s risk of heart disease and/or mortality.⁷

Coronary artery calcium levels are a good way to judge the overall extent of plaque buildup in a person’s arteries. Therefore it is a crucial tool in assessing someone’s risk of heart disease/problems.⁸

It can also help to reassess someone’s risk and to help healthcare professionals to make informed decisions when it comes to prevention strategies for heart disease.⁸

For example, an asymptomatic patient with no calcium would have a very low heart attack risk and thus would probably not need medications such as statins (tablets to lower cholesterol). 

Whereas an asymptomatic patient with a higher calcium score would have a higher heart attack risk and may need such medications to lower this risk. (British Heart Foundation).

In some cases, a coronary calcification scan may also be used to assess the extent of other heart conditions too. 

What happens in a coronary calcification scan?

Unlike a CT coronary angiogram, a coronary calcification scan is noninvasive, meaning that you will not be injected with anything or have to take any extra medications for it. As with the CT coronary angiogram, you will be connected to a monitor to measure your heart’s electrical activity. 

Once in the scanner, you will be asked to hold your breath while images are taken, but this won’t ever be for longer than 15 seconds at a time. The scan will last about fifteen minutes and will not cause any pain. 

You can find out more details on the NHS website here. 

What are the risks of a coronary calcification scan?

As there is no injection of a dye, the coronary calcification scan does not come with any risks except for the minimal level of radiation you will be exposed to. As previously mentioned, this is not a problem unless you are consistently exposed, and the outcomes of the scan are very much worth the minor risk (NHS). 

Summary

• You can have two different types of CT scans of the heart
• A CT coronary angiogram gives the radiographer a detailed view of the heart’s arteries
• This allows them to see how much plaque buildup there is and diagnose coronary heart disease
• For this scan, you’ll be injected with a dye beforehand so the blood flow can be seen on the scan
• There are minimal risks due to the radiation or the possibility of an allergic reaction to the dye or the dye leaking
• A coronary calcification scan is more simple and noninvasive
• It allows the radiographer to measure the calcified plaque in the arteries to give a calcium score
• This is used to assess asymptomatic patient’s risk of heart attacks
• For this scan, there is no injection and only the minimal risk of radiation