Acute coronary syndrome

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.

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 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.

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). In a myocardial infarction there is complete blockage of the artery, leading to death of heart muscle cells if treatment is not given promptly.

Symptoms of acute coronary syndrome

• The most common symptom is 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.

  • It may be similar to a bout of normal (stable) angina. However, it is usually more severe and lasts longer. ACS pain usually lasts more than 15 minutes.

• Some people with an ACS may not have any chest pain, particularly those who are elderly or those who have diabetes.

• You may also sweat, feel sick and feel faint.

• You may also feel short of breath.

Risk factors

ACS is common. Mostly it occurs in people aged over 50 and it becomes more common with increasing age. Sometimes younger people are affected.

The risk factors for having an ACS are the same as the risk factors for having cardiovascular disease. See the separate leaflet called Cardiovascular disease (Atheroma) for more details.

Diagnosing acute coronary syndrome

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.

One of the tests will be a heart tracing (electrocardiogram, or ECG). If you are having a heart attack, the ECG will help decide whether it is an ST-segment elevation myocardial infarction (STEMI) or a non-ST-segment elevation myocardial infarction (NSTEMI).

Acute coronary syndrome treatment

The treatment of ACS varies between cases. A heart attack is treated differently to unstable angina. Treatments may vary depending on your situation. A STEMI usually causes more damage to heart muscle than an NSTEMI.

See the separate leaflet called Heart attack (Myocardial infarction) for more details of treatment for a STEMI.

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 ECG looks like when you first attend the hospital.

See the separate leaflets called Heart attack (Myocardial infarction) and also Heart attack recovery for more details.

Preventing acute coronary syndrome

Prevention of acute coronary syndrome can be divided into primary prevention (stopping it from happening in the first place) and secondary prevention (stopping it from happening again after a first episode).

Primary Prevention of ACS

The following is advised to prevent suffering from acute coronary syndrome:

• Don't smoke.

• Eat a healthy diet.

• Take regular exercise.

• Maintain a healthy weight.

• Limit alcohol to 14 units per week.

• Keep high blood pressure under control.

• Keep diabetes under control.

• Take medication for high cholesterol, if you are advised to do so.

Secondary Prevention of ACS

If you have had an episode of ACS, your doctor will make further recommendations, in addition to the advice for primary prevention above. You may be advised to take the following medications:

• Blood thinners, the most commonly used ones are aspirin and clopidogrel. Some people are prescribed another blood thinner called ticagrelor. Sometimes in hospital a blood thinner called fondaparinux is given.

• ACE inhibitor such as ramipril or lisinopril.

• Beta blocker such as bisoprolol or carvedilol.

• A statin medication to lower your cholesterol, eg, atorvastatin.

Most people with ACS are offered a coronary angiogram to assess the blockage of the coronary arteries. Sometimes during the coronary angiogram it is possible to clear the blockage to improve the flow in the coronary arteries. This is called percutaneous coronary intervention (PCI). Your cardiologist will decide if you should have a coronary angiogram and when it should be done.

You should be offered cardiac rehabilitation after you leave hospital. This is an individualised programme of exercise, advice and support for people who have suffered from a heart problem.

What is the outlook for ACS?

The outlook for ACS depends on the specific condition, and how much heart muscle has been damaged. Prompt diagnosis and treatment minimises damage to heart muscle and recent developments in treatment have significantly improved the outlook.