This is a plain English summary of an original research article. The views expressed are those of the author(s) and reviewer(s) at the time of publication.
This study included 688 people with coronary heart disease who had previously had bypass surgery. They were all about to have an invasive heart X-ray (angiography) to check the replaced blood vessels. Researchers explored whether having a CT scan in advance could reduce the risks of the angiography.
Compared with patients who had the angiography only, people who also had the CT scan:
- had shorter angiographies
- were more satisfied with their care
- were less likely to have kidney injury related to the angiography
- had fewer complications.
The researchers hope their findings will influence guidelines.
More information about coronary heart disease can be found on the NHS website.
The issue: can a CT scan improve an angiography procedure?
In coronary heart disease, the blood supply to the heart (via the coronary arteries) is reduced because of a build-up of fatty substances. People with the condition might need surgery to bypass their coronary artery with a blood vessel taken from another part of the body. Surgeons perform about 20,000 of these bypasses in England each year.
Within 3 years of surgery, around 1 in 5 bypass patients need an invasive heart X-ray (called coronary angiography) to check the function of coronary arteries and bypass grafts. A flexible tube is put into a blood vessel in the groin or arm, and guided to the coronary arteries. Dye is injected through the tube to show on an X-ray any blood vessels that are narrowed or blocked. This procedure involves exposure to radiation and carries a risk of severe complications (including stroke). The dye itself can damage kidneys.
A CT scan before the angiography gives surgeons more information in advance. A dye is injected and the scan displays the bypasses.
In a randomised controlled trial, researchers explored whether such a CT scan could reduce the time taken for the angiography and exposure to the dye.
What’s new?
Researchers recruited 688 people between 2018 and 2021 from a specialist centre in London. Participants’ average age was 70, most were male (84%), and just over half (58%) were white. Most had had a triple bypass 12 years previously. Half (343) were assigned to have the CT scan before the angiography and most of this group (321) had both scans. The others (342) were assigned to angiography only.
In this study, the group that had both procedures:
- had shorter angiography procedures (19 minutes) than the angiography group (40 minutes)
- were happier with their care (97% rated their care as very good or good) than the angiography only group (46% said very good or good)
- were less likely to have kidney injury from the dye within 1 week of the procedure (3% people) compared with the angiography only group (28%)
- had fewer major heart problems 1 year later (16% people) compared with the angiography only group (29%) - this was a secondary outcome
- were less likely to have complications from angiography (2%) than the angiography only group (11%), mostly due to fewer heart attacks.
The CT scan eliminated problems inserting the flexible tube. And for 22 people, the CT scan alone gave sufficient information to mean the angiography was not required.
Why is this important?
This study shows that a CT scan can shorten the time an angiography takes, improve patient satisfaction and reduce procedure-related complications. It identified some people who did not need the angiography, and they avoided an invasive procedure.
The CT scan reduced exposure to the dye used in angiography, and therefore reduced kidney damage. However, although the CT scan reduced radiation exposure during angiography, overall, people who had both tests had increased exposure to radiation. This did not cause safety concerns after 1 year, but any longer-term consequences are unknown.
The researchers say that newer CT scanners are likely to further increase the benefits.
This research was carried out at a single centre in London, and needs to be replicated with participants who are representative of the UK population. But the findings are likely to be generalisable to people who typically require an angiography since most participants had other conditions such as hypertension (85%), diabetes (54%) and many had chronic kidney disease (40%).
What’s next?
CT scans before angiography are not yet available to everyone. The research team expects that their findings will influence National Institute for Health and Care Excellence and European Society of Cardiology guidelines on the management of patients undergoing angiography.
The research team has followed up people in this study over the longer-term (3 years); the publication is in press.
Can I act on this information?
What else do I need to know?
You may be interested to read
This is a summary of: Jones D, and others. Computed tomography cardiac angiography before invasive coronary angiography in patients with previous bypass surgery: the BYPASS-CTCA trial. Circulation 2023; 148: 1371 – 1380.
Watch an angiogram – video by the British Heart Foundation.
Angioplasty – your quick guide. An illustrated leaflet from the British Heart Foundation.
A study showing that another type of scan could reduce the number of people having an angiography: Greenwood JP, and others. Effect of care guided by cardiovascular magnetic resonance, myocardial perfusion scintigraphy, or NICE guidelines on subsequent unnecessary angiography rates. The CE-MARC 2 randomized clinical trial. Journal of the American Medical Association 2016; 316: 1051 – 1060.
Funding: This study was funded by the Research for Patient Benefit Programme.
Conflicts of Interest: One of the study authors receives institutional research support from a company that manufactures the CT scanner. See paper for full details.
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