There is no agreed definition for CSX. The underlying cause may be sudden narrowing (spasm) of normal coronary arteries without any atheroma.
What is cardiac syndrome X?
Cardiac syndrome X (CSX) is thought to be a type of angina. In CSX you feel chest pain when your heart works harder but the heart arteries appear to be normal on coronary angiography.
The term CSX is often used to describe microvascular angina. The larger blood vessels in the heart (that show up in investigations) are normal. However, much smaller vessels (the microvasculature) are thought to be where there is narrowing. Therefore, a better name for CSX would perhaps be 'microvascular angina'.
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 in men. Certain factors make CSX more likely to develop - for example:
- Having a high cholesterol level.
- Being overweight and unfit.
- Having high blood pressure.
- Women during or after the menopause.
- 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 cardiac syndrome X?
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 (oesophagus) or from your muscles and joints. They will usually also ask you about your lifestyle (whether you smoke and drink), your diet and whether 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' (electrocardiogram, or ECG) is often done. However, 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. A 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. The angiogram is usually normal in people with CSX. However, the angiogram may show narrowing when certain chemicals (for example, acetylcholine) are injected. The injection of these chemicals causing abnormalities in the angiogram helps to diagnose CSX.
What treatments are available?
CSX can be difficult to treat but a range of different treatments can help. The treatments include reducing risk factors as listed above. It is particularly important to have regular exercise.
Several different medicines may also be helpful, including calcium-channel blockers, beta-blockers, angiotensin-converting enzyme (ACE) inhibitors, ranolazine and statins. Oestrogen replacement therapy may also have a role for women who are affected after the menopause. Nitrates such as GTN may be effective for symptom relief.
Other treatments include a piece of equipment called a transcutaneous electrical nerve stimulation (TENS) machine or a spinal cord stimulator to reduce pain. Relaxation exercises, hypnotherapy and cognitive behavioural therapy can also be helpful.
What can I do to help myself?
Certain factors increase the risk of more fatty patches or plaques (atheroma) forming, which can make any type of angina worse. These are discussed in more detail in a separate leaflet called Preventing Cardiovascular Diseases.
What is the outlook?
CSX symptoms may 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.
Further reading and references
ESC Guidelines on the Management of Stable Coronary Artery Disease; Eur Heart J 201334:2949–3003
Fernandez SF, Tandar A, Boden WE; Emerging medical treatment for angina pectoris. Expert Opin Emerg Drugs. 2010 Apr 13.
Stable angina: management; NICE Clinical Guideline (August 2016)
Wee Y, Burns K, Bett N; Medical management of chronic stable angina. Aust Prescr. 2015 Aug38(4):131-6. Epub 2015 Aug 3.
Radico F, Cicchitti V, Zimarino M, et al; Angina pectoris and myocardial ischemia in the absence of obstructive coronary artery disease: practical considerations for diagnostic tests. JACC Cardiovasc Interv. 2014 May7(5):453-63. doi: 10.1016/j.jcin.2014.01.157. Epub 2014 Apr 16.
Hung MJ, Hu P, Hung MY; Coronary artery spasm: review and update. Int J Med Sci. 2014 Aug 2811(11):1161-71. doi: 10.7150/ijms.9623. eCollection 2014.
Agrawal S, Mehta PK, Bairey Merz CN; Cardiac Syndrome X: Update. Heart Fail Clin. 2016 Jan12(1):141-56. doi: 10.1016/j.hfc.2015.08.012.
Assessing fitness to drive: guide for medical professionals; Driver and Vehicle Licensing Agency