What is cardiac syndrome X?

Cardiac syndrome X (CSX) is thought to be a type of angina. Angina is a pain that comes from the heart. The common type of angina is usually caused by narrowing of the coronary (heart) arteries. This causes a reduced blood supply to a part, or parts, of your heart muscle. The blood supply may be good enough when you are resting. When your heart works harder (when you walk fast or climb stairs and your heart rate increases) your heart muscle needs more blood and oxygen. If the extra blood that your heart needs cannot get past the narrowed coronary arteries, the heart responds with pain.

The narrowing of the arteries is caused by atheroma. Atheroma is like fatty patches or plaques that develop within the inside lining of arteries. (This is similar to water pipes that get furred up with limescale.) Plaques of atheroma may gradually form over a number of years. They may be in one or more places in the coronary arteries.

In CSX you feel chest pain when your heart works harder, but the heart arteries appear to be normal.

CSX was first described in 1973. Since then researchers have had trouble deciding exactly what it is and what causes it. There have been many different theories, but the following are currently thought to explain why it might occur:

• The larger blood vessels in the heart (that show up in investigations) are normal. However, much smaller vessels (the microvasculature) is thought to be where there is narrowing. It is also thought that the lining of the heart's blood vessels (the endothelium) does not work as well in repairing itself.
• The heart muscle is very sensitive to pain. More sensitive than in people who don't have this condition.

A better name for CSX would perhaps be microvascular angina. This tells you what the problem is and avoids it being confused with metabolic syndrome, which is sometimes referred to as syndrome X.

How common is cardiac syndrome X?

Because doctors have not been able to decide exactly what CSX is, there are no precise numbers of how many people have the condition. Each year about 20,000 people in the UK develop angina for the first time. Of these people, about 1 woman in 5 and 1 man in 10, will have CSX. Unlike the more common type of angina, CSX is more common in women than men, and tends to affect younger people (between the ages of 40 and 50 years).

Certain factors make CSX more likely to develop. For example: having a high cholesterol level, smoking, being overweight and unfit, having high blood pressure, having diabetes or problems with your sugar levels, and also having mild arthritis.

What are the symptoms?

The common symptom is a pain, ache, discomfort or tightness that you feel across the front of the chest when you exert yourself - for example, when you walk up a hill or against a strong, cold wind. You may also, or just, feel the pain in your arms, jaw, neck or stomach.

An angina pain does not usually last long. It will usually ease within 10 minutes when you rest. Angina pain may also be triggered by other causes of a faster heart rate. For example, when you have a vivid dream or an argument. The pains also tend to develop more easily after meals.

CSX pain can be quite severe and disabling.

How do doctors diagnose CSX?

When you see your doctor, they will want to know all about the pain and when it happens. Angina-type pains have a pattern. They will also use this information to rule out other causes of pain, such as pain from the gullet or from your muscles and joints. They will usually also ask you about your lifestyle (whether you smoke and drink), your diet and if you exercise. They may also take a blood pressure reading. They may ask you to have a blood test to check your cholesterol level.

If they think angina is likely, they may prescribe you a glyceryl trinitrate (GTN) spray or tablets. You take a dose under your tongue when your angina pain develops. GTN is absorbed quickly into the bloodstream, from under the tongue, and should ease the pain within a few minutes. It works by relaxing the blood vessels. This reduces the workload on the heart. It also helps to widen the coronary arteries and increase the flow of blood to the heart muscle. A dose of GTN may cause a headache and/or flushing for a short while. If this medicine does not relieve the pain quickly, tell your doctor. Further tests may be needed.

A heart tracing called an electrocardiograph (ECG) is often done, but this is usually normal when you are not exerting yourself. When you have an ECG whilst exercising (sometimes called a stress test) the doctor may be able to see a typical pattern (a downward-sloping ST segment). This helps to make the diagnosis.

Typical angina can be confirmed by an angiogram test. This is when special dye is injected into the arteries or the heart (coronary arteries). X-ray equipment shows up the structure of the arteries and can also show the location and severity of any narrowing. This test is normal in people with CSX.

What treatments are available?

CSX can be tricky to treat. Treatments that usually work for the common type of angina don't seem to work as well for CSX.

The first treatment usually tried is a beta-blocker medicine. Research shows this has the best chance of improving symptoms, but it can vary. Treatments that help to modify the pain and how it is felt, can also be tried. These include imipramine or a piece of equipment called a transcutaneous electrical nerve stimulation (TENS) machine (as can be used for pain relief in labour).

Sometimes other medicines may also be advised, if you have high blood pressure or a high cholesterol level.

A lot of medicines have been tried over the years, without success. More research is needed to work out the most effective treatment.

What can I do to help myself?

Certain factors increase the risk of more atheroma forming, which can make any type of angina worse. These are discussed in more detail in a separate leaflet called 'Preventing Cardiovascular Diseases'. Briefly, risk factors that can be modified and may help to prevent angina from getting worse include:

• Smoking. If you smoke, you should make every effort to stop.
• High blood pressure. Your blood pressure should be checked regularly, at least once a year, if you have angina. If it is high, it can be treated.
• If you are overweight, losing some weight is advised. Losing weight will reduce the amount of workload on your heart and also help to lower your blood pressure.
• High cholesterol. This should be treated if it is high.
• Inactivity. If possible, you should aim to do some moderate physical activity on most days of the week for at least 30 minutes. For example, brisk walking, swimming, cycling, dancing, gardening, etc. (Occasionally, angina is due to a heart valve problem where physical activity may not be so good. Ask your doctor to confirm that you can undertake regular physical activity.)
• Diet. You should aim to eat a healthy diet. A healthy diet means:
  • At least five portions (and ideally 7-9 portions) of a variety of fruit and vegetables per day.
  • You should not eat much fatty food such as fatty meats, cheeses, full-cream milk, fried food, butter, etc. Ideally, you should use low-fat, monounsaturated or polyunsaturated spreads.
  • Try to include 2-3 portions of fish per week, at least one of which should be oily (such as herring, mackerel, sardines, kippers, salmon, or fresh tuna).
  • If you eat red meat, it is best to eat lean red meat, or eat poultry such as chicken.
  • If you do fry, choose a vegetable oil such as sunflower, rapeseed or olive.
  • Try not to add salt to food, and limit foods which are salty.
• Alcohol. Drinking a small or moderate amount of alcohol is probably beneficial to the heart. That is, 1-2 units per day - which is up to 14 units per week.

What is the outlook (prognosis)?

In about 1 out of 3 people with CSX, symptoms improve over time. Unfortunately, in about 1 out of 5 people, their symptoms become worse. The pain can become difficult to relieve and this affects the quality of life for people with CSX.

At the moment, CSX on its own does not appear to affect life expectancy. If there are also other problems, such as high blood pressure and cholesterol, life expectancy may be lower if they are not treated effectively.

Further help and information

British Heart Foundation

Greater London House, 180 Hampstead Road, London, NW1 7AW
Tel (Heart Help Line): 0300 330 3311 Web: www.bhf.org.uk

British Cardiac Patients Association

15 Abbey Road, Bingham, Notts, NG13 8EE
Tel (Helpline): 01223 846845 Web: www.bcpa.co.uk
Heart patients, their families and carers may find investigations or treatments difficult to understand and hard to accept. It can be a relief to share thoughts and concerns with people who have successfully passed through similar anxieties and problems.