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Causes - Coronary heart disease (CHD)

The main cause of coronary heart disease (CHD) is a build-up of a fatty substance in the arteries around your heart (coronary arteries).

The substance, called atheroma, makes your arteries narrower. This restricts the flow of blood to your heart muscle. This is called atherosclerosis.

Your risk of developing atherosclerosis is much higher if you:

  • smoke
  • have high blood pressure (hypertension)
  • have high cholesterol
  • do not exercise often
  • have diabetes
  • have obesity or overweight
  • having a family history of CHD

The risk is higher if a male relative under 55 or a female relative under 65 has CHD.

High cholesterol

Cholesterol is a fat made by the liver from the saturated fat in your diet. Your body needs some cholesterol, but too much in the blood can lead to CHD.

High cholesterol

High blood pressure

High blood pressure (hypertension) puts a strain on your heart and can lead to CHD.

High blood pressure (hypertension)


Smoking is a major risk factor for CHD. Nicotine and carbon monoxide (from the smoke) put a strain on your heart by making it work faster. They also increase your risk of blood clots.

If you smoke, you increase your risk of developing heart disease by almost a quarter. Heart disease can cause blocked arteries.

Get support to stop smoking


Diabetes can double your risk of developing CHD. It may cause the lining of your blood vessels to become thicker. This can restrict blood flow.



A thrombosis is a blood clot in a vein or artery.

If you get a clot in a coronary artery, it prevents the blood supply from reaching the heart muscle. This may cause a heart attack.

Content supplied by the NHS and adapted for Ireland by the HSE

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This project has received funding from the Government of Ireland’s Sláintecare Integration Fund 2019 under Grant Agreement Number 123.

Page last reviewed: 6 December 2023
Next review due: 6 December 2026