Premature Coronary Artery Disease and Familial Hypercholesterolemia

What are premature coronary artery disease and familial hypercholesterolemia?

The heart muscle requires a regular supply of oxygen and food. This is supplied by blood carried by a network of blood vessels known as the coronary arteries.

The coronary arteries can become narrowed by ‘furring’ of the artery wall with cholesterol, called atherosclerotic plaques. Blood clots can form on these plaques and block the artery, causing chest pains. The heart muscle supplied by the blocked artery is starved of oxygen and dies soon afterwards, known as a heart attack. This can also cause dangerous arrhythmias. The build-up of plaques in the coronary arteries increases with age and most people who have significant narrowing are usually over 50 years of age.

There is a genetic component to the risk for developing coronary artery disease, but many factors are involved, including smoking, high blood pressure, diabetes and cholesterol levels. Some families carry gene mutations that make them likely to have a very high cholesterol levels. This is known as familial hypercholesterolemia or FH. Families usually have members who have suffered from heart attacks, sometimes at very young ages.

What are the symptoms?

A person with narrowed arteries may experience heavy or tight chest pain – called angina – or breathlessness, most commonly during exertion. A person who has FH may develop fatty lumps in the skin around the eyes or in the muscle tendons, but, usually, the only way of telling is to have a blood test.

How is it diagnosed?

An ECG at rest will often be normal. An exercise ECG may show signs that the heart is being starved of oxygen. Depending on how high the doctor thinks the risk of having narrowed coronary arteries is, a range of different tests may also be offered, such as an ECHO during exercise, a special MRI scan or a CT scan of the coronary arteries. If the doctor thinks risk is high then coronary angiography may be offered to diagnose the condition.

Treatment and advice

Anyone with coronary artery disease should receive advice on lifestyle – including stopping smoking, a healthy diet and regular exercise. If cholesterol levels are high they can be treated with tablets, known as statins, to reduce the risk of further artery furring. There are several tablets that can also treat symptoms of chest pain and reduce the chance of a heart attack. These include aspirin, statins, and beta-blockers.

Significant narrowings in the coronary arteries can be treated by inflating a balloon at the narrowing (known as angioplasty) and inserting a metal tube (stent) to keep the artery open. Alternatively a coronary artery bypass operation (CABO) may be required.

More about familial hypercholesterolemia (FH)

The NICE guidelines state:

  • A family history of premature coronary heart disease should always be assessed in a person being considered for a diagnosis of FH.
  • In children at risk of FH because of one affected parent, the following diagnostic tests should be carried out by the age of 10 years, or at the earliest opportunity thereafter: (1) a DNA test if the family mutation is known; (2) LDL-C concentration measurement if the family mutation is not known. When excluding a diagnosis of FH, a further LDL-C measurement should be repeated after puberty because LDL-C concentrations change during puberty.
  • Coronary heart disease risk estimation tools such as those based on the Framingham algorithm should not be used because people with FH are already at a high risk of premature coronary heart disease.

Identifying people with FH using cascade testing:

  • Healthcare professionals should offer all people with FH a referral to a specialist with expertise in FH for confirmation of diagnosis and initiation of cascade testing.
  • Cascade testing using a combination of DNA testing and LDL-C concentration measurement is recommended to identify affected relatives of those index individuals with a clinical diagnosis of FH. This should include at least the first- and second- and, when possible, third-degree biological relatives.

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