Researchers used artificial intelligence (AI) to analyse routine heart scans from more than 1700 people, mostly in their fifties, who had chest pain. They found that people with greater muscle density in their chest and back were less likely to have a heart attack or die in the decade after having the scan.
The research team say that people with higher-quality skeletal muscle tend to be more physically active and have stronger torso muscles. Their findings suggest this may contribute to a lower risk of heart attack and early death.
Muscle density
Around 350,000 people have a CCTA scan in the UK each year to identify any narrowing or blockages in the coronary arteries that supply the heart muscle with blood, which may put them at risk of a heart attack.
The University of Edinburgh-led research team took a deeper dive into CCTA scan images, using AI to examine people’s muscle, organs, bones and the fat within their upper bodies. This included looking at skeletal muscle attenuation – the brightness or darkness of the muscle in a scan.
A brighter image indicates that someone has better quality, more dense muscle, which may contain a lower proportion of fat. Fat within people’s muscle has previously been linked to poor cardiovascular health.
The new study grouped people based on how their muscle appeared in scan images, and investigated rates of heart attacks and early deaths using health records.
Reduced risk
For every 10-point increase in scan brightness, indicating better quality muscle with less fat, a person was calculated to be 31 per cent less likely to have a heart attack. They were also 39 per cent less likely to die in the 10 years after having the scan.
This was seen even after taking into account other factors which may increase people’s risk of heart attacks and death, including their age, sex and the amount of calcium which had built up in their arteries.
The AI used in the study took no longer than a minute to measure the quality of someone’s muscle from a single scan. A radiologist would take several hours to do the same thing.
Heart protection
More evidence is needed on how people’s muscle quality may affect their heart health or risk of dying prematurely, researchers say. It is likely that people who exercise enough to have strong muscles in their upper body have a healthy lifestyle which protects their heart in other ways, they add.
All kinds of exercise, not just strength-training, can improve muscle density. The size of people’s muscles was not linked to their risk of a heart attack or early death, suggesting it is the composition of the muscle which matters.
The results suggest that routine heart scans could in future be used to identify people with less good-quality muscle who may be at greater risk of heart attacks, experts say. Higher risk people could then be helped to exercise more, be monitored more closely, or prioritised for drugs such as statins, which can reduce the risk of a heart attack, they add.
However, more research is needed before scans could be relied upon in this way.
The study, part-funded by the British Heart Foundation, was published in the journal Radiology.