Strong chest and back muscles may significantly lower heart attack risk, according to an artificial intelligence analysis of hospital scans that examined the quality of skeletal muscle in patients with chest pain.
AI analysis reveals link between muscle density and heart health
Researchers at the University of Edinburgh used artificial intelligence to examine coronary computed tomography angiogram (CCTA) scans of 1,722 patients, predominantly in their 50s, who had presented with chest pain. The AI tool measured skeletal muscle attenuation – the brightness or darkness of muscle tissue in the scan – taking approximately one minute per analysis, a task that would otherwise require a radiologist several hours. CCTA scans are routinely performed in the UK, with around 350,000 carried out each year to detect narrowing or blockages in coronary arteries.
The AI assessed the density of muscles in the upper body, with a particular focus on the back muscles, part of the pectoral muscles (the “pecs”), and the intercostal muscles between the ribs. Denser muscle appears lighter in a scan because more X‑ray beams bounce off it, indicating better quality muscle with a lower proportion of fat. The study, published in the journal Radiology and part‑funded by the British Heart Foundation, found that for every ten‑point increase in scan brightness – signalling higher‑quality, less fatty muscle – a person was 31% less likely to have a heart attack and 39% less likely to die in the decade following the scan.
Muscle composition matters more than size
Crucially, the size of a person’s muscles was not linked to their risk of a heart attack or early death. The researchers said this indicates that it is the composition of the muscle – its quality and fat content – that matters, not its bulk. Broader research has shown that skeletal muscle quality, rather than quantity alone, is a strong predictor of diabetes, major cardiovascular events and mortality, and that fat stored inside muscle (intramuscular fat) is specifically associated with poor cardiovascular health. Skeletal muscle plays a vital role in metabolic health, influencing heart outcomes through glucose regulation, energy metabolism, and inflammatory responses.
The study’s senior author, Professor Michelle Williams, Professor of Cardiovascular Imaging at the University of Edinburgh and an Honorary Consultant Radiologist at NHS Lothian, said the findings were so compelling that she has started going to the gym twice a week and aims to walk for an hour every day. “It is fascinating that people’s skeletal muscle could be linked to their risk of having a heart attack,” she said. “The muscles which show up in the scans we used – coronary computed tomography angiogram scans – are principally the back muscles, part of the pectoral muscles – or ‘pecs’ – and the intercostal muscles between the ribs. So I am now personally interested in exercises like cycling, planks and pilates, which I enjoy and may have an effect on these muscles. However, we need far more research to better understand how exercise may affect muscle density, and how this may relate to heart health.”
Implications for future heart health
The researchers suspect that people with higher muscle density are those who exercise more and possess greater strength in their torsos. Both aerobic exercise and resistance training are known to benefit heart and circulatory health, and even moderate physical activity can lower blood pressure, reduce the risk of diabetes, help maintain a healthy weight, and decrease inflammation.
In future, routine heart scans could be used to identify individuals with lower‑quality muscle who may be at greater risk of heart attacks. Those people could then be helped to exercise more, be monitored more closely, or be prioritised for drugs that reduce the risk of a heart attack. The AI tool could also be used opportunistically with routine imaging scans – not only CCTA but also other CT or MRI scans – to assess body composition and identify at‑risk individuals, potentially moving beyond traditional measures such as BMI.
Professor Bryan Williams, Chief Scientific and Medical Officer at the British Heart Foundation and Chair of Medicine at University College London, said: “It is likely that people in this study with more dense muscle mass were more physically active and as a result may have better heart health. That is yet more evidence supporting the power of exercise.”