Coronary Microvascular Disease - the hidden cause of Heart Attacks

Most people who experience heart attacks will usually have associated risk factors which puts them at a higher risk of developing coronary artery disease or cardiovascular disease, which could later lead to a heart attack.

Risk factors are usually split into two categories: modifiable (which an individual can change and can, in the most part, be reversible), and non-modifiable (which cannot be changed).

Modifiable risk factors can include obesity or high BMI, a poor diet, high cholesterol levels (known as hypercholesterolaemia), high blood pressure (known as hypertension), diabetes and smoking, all of which put someone at a higher risk of cardiovascular disease which could lead to a heart attack.

Non-modifiable risk factors can include simple things such as age and gender, as well as more complex risk factors such as congenital heart issues (from birth), genetic predisposition or even higher risks of heart disease determined by someones ethnic background.

However, even some people with no visible risk factors might experience a heart attack which might mean that some people are doubtful of their symptoms. These 'silent' risk factors may only present themselves when a heart attack occurs and so someone may not be aware of any issues until an attack occurs.

A Harvard University study investigating the dangers of “hidden” intramuscular fat found that for every one per cent increase in ‘fatty muscle fraction’ – aka the amount of fat stored in the muscle – there was a two per cent increased risk of coronary microvascular dysfunction (CMD), one of the earliest signs of heart disease.

CMD affects the small blood vessels of the heart, causing symptoms including chest pain and breathlessness and potentially leading to arterial blockages, heart attack, heart failure or stroke.

In February 2025, Dr. Jogiya spoke to the i Newspaper about the risks of microvascular disease. Dr Jogiya is a Consultant Cardiologist at Kingston Hospital in Kingston-upon-Thames and St Thomas' Hospital in London, and also serves as the Chief Medical Adviser for Heart Research UK.

He described microvascular circulation by saying: "While some fat in the muscles is normal, too much can interfere with muscle function and is linked to inflammation and poor blood flow in the heart’s small blood vessels. This increases the risk of heart attacks and other cardiovascular problems, regardless of body weight.”

Read about Gail's story and how she had a heart attack with no clear risk factors. Find the article below, or find it here: Coronary Microvascular Disease

Article written in February 2025

Article Written: 21 April 2025

Review Date: April 2027