A CTCA scan, short for CT coronary angiography, is a non invasive imaging test used to assess the coronary arteries. These are the blood vessels that supply the heart muscle. Many patients are referred for a CTCA scan when there is a need to understand whether chest symptoms or cardiac risk factors are linked to narrowing or plaque within these arteries.
Hearing that a scan of the heart arteries is needed can cause concern, but a CTCA scan is now a well established and widely used investigation. It provides detailed information and is often reassuring when results are normal.
Why a CTCA scan is performed
The main purpose of a CTCA scan is to look for plaque or narrowing in the coronary arteries. These changes are part of coronary heart disease and develop gradually over time and may not always cause symptoms in the early stages.
A CTCA scan may be recommended if:
- there is chest pain or discomfort that needs clarification
- symptoms occur with exertion
- there are cardiac risk factors such as high cholesterol or family history
- previous tests have been inconclusive
- there is a need to guide decisions about medication
The scan helps determine whether coronary artery disease is present and, if so, how extensive it is.
What a CTCA scan involves
A CTCA scan is performed using a specialised CT scanner. The test itself is painless and usually takes only a short time, although the full appointment may last around an hour.
You will lie on a scanning table that moves through the CT scanner. Small sticky pads may be placed on the chest to monitor the heart rate during the scan.
A contrast dye is injected into a vein, usually in the arm. This allows the coronary arteries to be seen clearly on the scan images. The injection can cause a brief warm sensation, which passes quickly.
During the scan, you will be asked to lie still and may be asked to hold your breath for a few seconds at a time. The scanner takes detailed images of the heart and coronary arteries while the heart is beating.
Heart rate control during the scan
For a CTCA scan to be clear, the heart rate needs to be steady and relatively slow. If your heart rate is higher than ideal, medication may be given before the scan to slow it down temporarily.
This medication is commonly a beta blocker and is used safely in this setting. Not everyone requires it, but it helps improve image quality when needed. In some cases, a spray or tablet may also be given to slightly widen the coronary arteries, improving visual detail.
Is a CTCA scan safe?
CTCA scans are generally very safe. The amount of radiation used is carefully controlled and kept as low as possible while still producing high quality images.
The contrast dye is well tolerated by most people. Before the scan, you will be asked about kidney function, allergies, and previous reactions to contrast to ensure it is appropriate for you.
The benefits of the scan in clarifying diagnosis and guiding management usually outweigh the small risks involved.
How to prepare for a CTCA scan
Preparation instructions may vary slightly depending on where the scan is performed, but you are usually advised to:
- avoid caffeine for 24 hours beforehand
- not eat for a few hours before the scan
- continue usual medications unless advised otherwise
You should inform the team if you have asthma, kidney problems, or known contrast allergies. Wearing comfortable clothing and allowing enough time for the appointment helps reduce stress on the day.
What a CTCA scan can show
A CTCA scan provides detailed images of the coronary arteries. It can show:
- whether plaque is present
- how much narrowing there is, if any
- whether arteries are normal or affected
- the overall pattern of coronary artery disease
This information is very helpful in determining whether symptoms are likely to be cardiac in origin and whether treatment is required.
A normal CTCA scan is particularly reassuring and effectively rules out significant coronary artery disease.
What a CTCA scan cannot show
While a CTCA scan is very informative, it does not assess everything.
It does not directly measure how well the heart muscle pumps or how the heart valves function. These are usually assessed with echocardiography.
It also does not assess heart rhythm problems, which require ECG monitoring.
The scan provides anatomical information rather than functional information, which is why results are interpreted alongside symptoms and other test findings.
Understanding the results
Results are usually reported in terms of the presence and severity of coronary artery disease. Some people have completely normal arteries. Others may have mild plaque that does not significantly restrict blood flow. In these cases, lifestyle changes and medication may be advised to reduce future risk.
More significant narrowing may prompt further investigation or treatment, depending on symptoms and overall risk. Importantly, the findings help guide decisions rather than dictate them. The same scan result may lead to different recommendations in different individuals.
How CTCA results influence treatment
CTCA scans are particularly useful in deciding whether cholesterol lowering medication such as statins is appropriate. They help move the discussion away from treating numbers alone and towards treating actual risk. If plaque is present, treatment focuses on reducing progression and preventing future problems. If the scan is normal, unnecessary medication may be avoided. This tailored approach is one of the main strengths of CTCA scanning.
When a CTCA scan is not suitable
CTCA scans may not be suitable for everyone. Very irregular heart rhythms, severe kidney disease, or certain allergies may limit its use. In these cases, alternative tests may be recommended to obtain the necessary information.
When to seek advice
If you have been advised to have a CTCA scan, or if you would like to understand whether it is appropriate for your symptoms or risk factors, it is important to discuss this in context.
If you would like to talk through the role of a CTCA scan or review results you have already had, you can get in touch with me to arrange an assessment and discuss the findings in a clear and measured way.
A CTCA scan is a powerful diagnostic tool. When used appropriately, it provides clarity, reassurance, and guidance, helping ensure that investigation and treatment are proportionate and evidence based.