That is the conclusion of a large study of around 480,000 UK adults led by researchers from the MRC Institute of Medical Sciences (LMS) and Imperial College London. The researchers believe it is the largest study of its kind.

The findings suggest that chronic inflammation may contribute to harmful changes in heart structure and is associated with an increased risk of heart attack and stroke.

Importantly, these changes can begin years before cardiovascular symptoms appear, allowing damage to accumulate silently over time.

How chronic inflammation may affect the heart

Chronic inflammation occurs when the immune system remains mildly activated for long periods instead of returning to normal after an immediate threat has passed. This sustained, low-level immune response has been linked to diseases including cancer and diabetes, and researchers increasingly suspect that it may also play an important role in heart disease.

Professor Declan O’Regan, British Heart Foundation Chair of Cardiovascular AI at Imperial College London and head of the Computational Cardiac Imaging Group at LMS, said the study raises the possibility that millions of people may be living with hidden inflammation.

“Chronic inflammation is complex, but we know it is linked to our health and is driven by different lifestyles and economics,” he said. “Factors including the environment, economic situation, family health and lifestyle can all mean that people are more at risk.”

“However, while addressing health disparities remains a challenge, there are things we can do about inflammation, including reducing risk factors such as smoking and obesity.”

High inflammation linked to 43% higher cardiovascular risk

For the study, researchers analysed UK Biobank data from around 480,000 adults. They used a blood marker called glycoprotein acetyl, or GlycA, to assess inflammation and combined the measurements with cardiac imaging and genetic information.

Participants with the highest inflammation levels—the top 20%—had a 43% higher risk of heart attack or stroke than those with the lowest levels, or the bottom 20%.

The researchers also found evidence that inflammation was associated with physical remodelling of the heart. People with higher inflammation levels tended to have thicker heart walls, smaller heart chambers and less filling. These changes can develop silently over many years before potentially progressing to heart failure.

Persistent inflammation was associated with a higher risk of heart attack or stroke even among people with no previous history of heart disease.

Inflammation was also strongly associated with socioeconomic disadvantage and psychological distress. Established cardiovascular risk factors, including smoking and excess body fat, were also linked to higher inflammation levels.

Social factors, mental health and genetics may influence heart health

The findings suggest that inflammation may be one biological pathway through which pressures such as poverty and mental health problems affect the body and increase cardiovascular risk.

Professor O’Regan said the researchers were surprised by the extent to which social factors and mental health, alongside established risk factors such as smoking and lack of exercise, were linked to inflammation and heart damage.

“There are also strong genetic factors, with some people naturally more resilient and others more susceptible to inflammatory damage from different lifestyles,” he said.

However, the researchers stressed that heart disease is not inevitable because of genetic susceptibility or difficult living conditions. There may still be opportunities to reduce persistent inflammation and lower cardiovascular risk.

The analysis also identified inflammatory proteins from the interleukin-1 and tumour necrosis factor, or TNF, families as possible contributors to the observed cardiac damage.

Some of these proteins are already being targeted by drugs in clinical trials. This raises the possibility that anti-inflammatory therapies could eventually help prevent cardiovascular disease before symptoms appear, although further research is needed.

Could blood tests identify people at risk?

The researchers suggest that blood tests for inflammation could eventually be combined with genetic risk scores to identify people who may benefit most from early intervention.

Professor Brian Williams, chief scientific and medical officer at the British Heart Foundation, said inflammation is part of the body’s healing process but can also have harmful effects.

“This large-scale study found that people with high levels of inflammation experience quiet changes to the structure of their heart and are at increased risk of serious cardiac events such as heart attack and stroke,” he said.

“This study provides valuable insight into how our genes and lifestyle factors, such as smoking, poor mental health and socioeconomic status, cause inflammation. We also identified several inflammatory proteins that appear to play important roles in cardiac changes associated with chronic inflammation, giving hope that anti-inflammatory drugs may become important tools to prevent cardiovascular disease.”

“These findings confirm the importance of addressing the causes of inflammation and poor cardiovascular health, while supporting people to make lifestyle changes to protect their hearts.”

This research was funded by the Medical Research Council and the British Heart Foundation.

This work includes the NIHR Imperial Biomedical Research Centre, a translational research partnership between Imperial College Healthcare NHS Trust and Imperial College London.