Study Reveals Fatty Muscle Increases Heart Disease Risk - Video

People with pockets of fat hidden inside their muscles are at a higher risk of dying or being hospitalised from a heart attack or heart failure, regardless of their body mass index, according to research published in the European Heart Journal.

The new finding adds evidence that existing measures, such as body mass index or waist circumference, are not adequate to evaluate the risk of heart disease accurately for all people.

The new research included 669 people who were being evaluated at the Brigham and Women’s Hospital for chest pain and/or shortness of breath and found to have no evidence of obstructive coronary artery disease. These patients had an average age of 63. All the patients were tested with cardiac positron emission tomography/computed tomography (PET/CT) scanning to assess how well their hearts were functioning. Researchers also used

CT scans to analyse each patient’s body composition, measuring the amounts and location of fat and muscle in a section of their torso. To quantify the amount of fat stored within muscles, researchers calculated the ratio of intermuscular fat to total muscle plus fat, a measurement they called the fatty muscle fraction.

Patients were followed up for around six years and researchers recorded whether any patients died or were hospitalised for a heart attack or heart failure.

Researchers found that people with higher amounts of fat stored in their muscles were more likely to have damage to the tiny blood vessels that serve the heart, and they were more likely to go on to die or be hospitalised for heart disease. For every 1% increase in fatty muscle fraction, there was a 2% increase in the risk of coronary microvascular dysfunction and a 7% increased risk of future serious heart disease, regardless of other known risk factors and body mass index.

People who had high levels of intermuscular fat and evidence of coronary microvascular dysfunction were at an especially high risk of death, heart attack and heart failure. In contrast, people with higher amounts of lean muscle had a lower risk. Fat stored under the skin did not increase the risk.

Professor Viviany Taqueti, Director of the Cardiac Stress Laboratory at Brigham and Women's Hospital and Faculty at Harvard Medical School, Boston, USA said: “Compared to subcutaneous fat, fat stored in muscles may be contributing to inflammation and altered glucose metabolism leading to insulin resistance and metabolic syndrome. In turn, these chronic insults can cause damage to blood vessels, including those that supply the heart, and the heart muscle itself.

Reference: Ana Carolina do A H Souza, Amelie S Troschel, Jan P Marquardt, Ibrahim Hadžić, Borek Foldyna, Filipe A Moura, Jon Hainer, Sanjay Divakaran, Ron Blankstein, Sharmila Dorbala, Marcelo F Di Carli, Hugo J W L Aerts, Michael T Lu, Florian J Fintelmann, Viviany R Taqueti, Skeletal muscle adiposity, coronary microvascular dysfunction, and adverse cardiovascular outcomes, European Heart Journal, 2025;, ehae827, https://doi.org/10.1093/eurheartj/ehae827