What is acute coronary syndrome?
The term 'acute coronary syndrome' (ACS) covers a range of disorders, including a heart attack (myocardial infarction) and unstable angina, that are caused by the same underlying problem. Unstable angina occurs when the blood clot causes a reduced blood flow but not a total blockage. This means that the heart muscle supplied by the affected artery does not die (infarct).
The underlying problem is a sudden reduction of blood flow to part of the heart muscle. This is usually caused by a blood clot that forms on a patch of atheroma within a coronary artery (which is described below).
The types of problems range from unstable angina to an actual myocardial infarction. In unstable angina a blood clot causes reduced blood flow but not a total blockage. Therefore, the heart muscle supplied by the affected artery does not die (infarct). The location of the blockage, the length of time that blood flow is blocked and the amount of damage that occurs determine the type of ACS.
What causes acute coronary syndrome?
The majority of cases of ACS are due to there being some narrowing in the blood vessels supplying the heart. This is usually due to the presence of some atheroma within the lining of the artery. 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.) Plaques of atheroma may gradually form over a number of years in one or more places in the coronary arteries. Each plaque has an outer firm shell with a soft inner fatty core. Atheroma leads to the blood vessels narrowing.
Various other uncommon conditions can also block a coronary artery. For example:
- Inflammation of the coronary arteries (rare).
- A stab wound to the heart.
- A blood clot forming elsewhere in the body (for example, in a heart chamber) and travelling to a coronary artery where it gets stuck.
- Taking cocaine, which can cause a coronary artery to go into spasm.
- Complications from heart surgery.
- Some other rare heart problems.
Who is at risk of having acute coronary syndrome?
ACS is common. About 114,000 people in the UK are admitted to hospital with an ACS each year. Most occur in people aged over 50 and become more common with increasing age. Sometimes younger people are affected.
The risk factors for having an ACS are actually the same as the risk factors for having a heart attack or cardiovascular disease. See separate leaflet called Preventing Cardiovascular Diseases for more details.
What are the symptoms of acute coronary syndrome?
- The most common symptom of a ACS is having severe chest pain. The pain often feels like a heavy pressure on your chest. The pain may also travel up into your jaw and down your left arm, or down both arms. You may also sweat, feel sick and feel faint. You may also feel short of breath.
- The pain may be similar to a bout of normal (stable) angina. However, it is usually more severe and lasts longer. (In people who have stable angina, an angina pain usually goes off after a few minutes. ACS pain usually lasts more than 15 minutes - sometimes several hours.)
- Some people with an ACS may not have any chest pain, particularly those who are elderly or those who have diabetes.
What tests are usually done?
It can sometimes be difficult for doctors to distinguish between ACS and other causes of pains in the chest. If you are suspected of having ACS then you should be referred urgently to hospital. On admission to hospital, various tests are usually done. These are usually the same as for a suspected heart attack.
What is the treatment for acute coronary syndrome?
The treatment of ACS varies between cases. A heart attack is treated differently to unstable angina. Treatments may vary depending on your situation.
If you have had a STEMI then you will be treated the same as those who have had a heart attack (myocardial infarction).
Treatment of people with unstable angina or NSTEMI consists of two phases:
- Relief of any pain.
- Preventing progression to, or limiting the extent of, a heart attack.
Your treatment usually varies depending on your risk score. This is a risk score for a further heart attack. Various factors are taken into account for this score, including:
- Your age.
- Your other risk factors for cardiovascular disease (for example, if you smoke, have raised cholesterol or have high blood pressure or diabetes).
- Your blood test results.
- What your heart tracing (electrocardiogram, or ECG) looks like when you first attend the hospital.
Glycoprotein llb/lla receptor antagonist
If the doctors think that you have a high risk of having a heart attack, you may be given a medicine called a glycoprotein llb/lla receptor antagonist. This can help relieve your pain. It also works to reduce the chances of blood clots completely blocking your arteries. This medicine is given to you as a drip, directly into your veins. This medicine is also used if you are going to have a treatment to help widen your arteries (for example, an angioplasty).
Treatment after you have had an ACS
Many people recover well from an ACS and have no complications. Before discharge from hospital it is common for a healthcare professional to advise you how to reduce any risk factors (see above). This advice aims to reduce your risk of a future ACS or heart attack as much as possible.
Much can be done to reduce the risk of a further ACS or a heart attack. Read more about after a heart attack (myocardial infarction) and also medication after a heart attack (myocardial infarction) for more details.
Further reading and references
Myocardial infarction with ST-segment elevation: The acute management of myocardial infarction with ST-segment elevation; NICE Clinical Guideline (July 2013)
2015 ESC Guidelines for the management of acute coronary syndromes in patients presenting without persistent ST-segment elevation; European Society of Cardiology (August 2015)
Ibanez B, James S, Agewall S, et al; 2017 ESC Guidelines for the management of acute myocardial infarction in patients presenting with ST-segment elevation: The Task Force for the management of acute myocardial infarction in patients presenting with ST-segment elevation of the European Society of Cardiology (ESC). Eur Heart J. 2017 Aug 26. doi: 10.1093/eurheartj/ehx393.
Valgimigli M, Bueno H, Byrne RA, et al; 2017 ESC focused update on dual antiplatelet therapy in coronary artery disease developed in collaboration with EACTS: The Task Force for dual antiplatelet therapy in coronary artery disease of the European Society of Cardiology (ESC) and of the European Association for Cardio-Thoracic Surgery (EACTS). Eur Heart J. 2017 Aug 26. doi: 10.1093/eurheartj/ehx419.
Unstable angina and NSTEMI; NICE Clinical Guideline (March 2010 - last updated November 2013)
Acute coronary syndrome; Scottish Intercollegiate Guidelines Network - SIGN (2016)
Myocardial infarction: cardiac rehabilitation and prevention of further MI; NICE Clinical Guideline (November 2013)
2014 ESC/EACTS Guidelines on myocardial revascularization; The Task Force on Myocardial Revascularization of the European Society of Cardiology and the European Association for Cardio-Thoracic Surgery (Aug 2014)
Mehta LS, Beckie TM, DeVon HA, et al; Acute Myocardial Infarction in Women: A Scientific Statement From the American Heart Association. Circulation. 2016 Mar 1133(9):916-47. doi: 10.1161/CIR.0000000000000351. Epub 2016 Jan 25.
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