Angina

What is it angina?

Angina pain develops when the muscles of the heart are not getting enough oxygen. This is usually caused by narrowing or blockages of the coronary arteries that deliver oxygen-rich blood to the heart muscle, known as coronary artery disease. Angina is a sign of heart disease.

If the blockage of a coronary artery progresses and becomes complete, the blood supply to part of the muscles of the heart is lost, causing a heart attack. Angina is a warning sign that the heart is at risk of an attack and should be taken very seriously. One patient in 10 will go on to have a heart attack within a year of diagnosis of angina.

Angina may be an occasional problem or may rapidly increase in severity and duration until a heart attack occurs.

Symptoms of angina

Symptoms of angina include:

• Pain in the chest, which may begin as a vague discomfort or ache usually in the centre of the chest. The type of pain varies and may be described as tightness, burning, crushing, pressure or heaviness. Some people get a choking sensation.
• The pain may radiate or move, typically to the neck, shoulder, jaw or down into the left arm.
• The pain usually lasts just a few minutes and quickly responds to treatment (usually glyceryl trinitrate (GTN) as tablets or spray under the tongue).
• The person may also feel short of breath, anxious or nauseous.

Causes of angina

Angina is common - about eight per cent of men and three per cent of women aged between 55 and 64 have experienced it, and it becomes more common with age.

It's most commonly caused by narrowing of the arteries that carry oxygen to the heart muscle by a process called atherosclerosis (sometimes known as hardening of the arteries). This is a common condition where fatty deposits or plaques build up in the coronary arteries. Symptoms don't usually develop until there is at least a 50 per cent blockage of the artery.

Most people in the developed world will have some atherosclerosis by the time they reach mid-life (and often much earlier), but some conditions can make it worse including:

• High cholesterol - especially if there's an inherited tendency to high cholesterol or a strong family history of heart disease
• Cigarette smoking
• Diabetes mellitus
• High blood pressure

Other conditions can also interfere with the blood supply to the heart muscle and lead to angina. These include:

• Abnormal heart rhythms - for example when the heart beats so fast it isn't pumping blood efficiently around the body
• Heart valve disease
• Inherited structural abnormalities of the coronary arteries
• Severe anaemia - where the blood count is so low that it cannot carry much oxygen to the tissues

Other important risk factors for angina include obesity and raised levels of chemical in the blood called homocysteine, or other chemicals involved with clotting.

In another condition, called Prinzmetal's angina or coronary artery spasm, the coronary arteries aren't permanently blocked but intermittently narrowed by spasm. This often develops in the early hours of the morning and may last up to 30 minutes. Those affected may also complain of palpitations and abnormal heart rhythms, or have similar conditions linked to spasm of the arteries such as migraine or Raynaud's phenomenon.

Events which put extra strain on the heart can make angina worse, such as:

• Fever
• Infection and serious illness
• Emotional stress
• Overactive thyroid gland
• Sudden extreme exertion

However, angina can come on at rest, even when a person is lying in bed.

Tests for angina

Many problems can be confused with angina, especially indigestion or gastro-oesophageal reflux. It's important tests are done to establish the diagnosis, to ensure the affected person gets the right treatment.

An electrocardiogram (ECG) is essential and may show typical changes but can be normal in angina. Blood tests can be done to check for causes such as anaemia and look for chemical enzymes (called Troponins) released from the heart if a heart attack has occurred. Other checks for cholesterol levels, blood fats, diabetes and thyroid disease may be done. In most areas of the UK these tests will be done at the local Rapid Access Chest Pain Clinic.

More complex tests such as an ECG during exercise, echocardiogram or other sophisticated x-ray tests may be recommended. However, NICE has recently produced guidelines which direct which tests should be done based on a statistical calculation of how likely to patient is to have angina. For example, invasive coronary angiography (where a tube is inserted into the coronary arteries and dye injected to produce x-rays pictures of the coronary arteries) is usually offered when there is a greater than 61 per cent chance of coronary artery disease.

Treatment of angina

Treatment of angina includes:

• Lifestyle advice to manage risk factors, such as weight loss, exercise, quitting smoking and a healthy diet.
• Medical treatment, including a drug called glyceryl trinitrate or GTN which can be taken repeatedly as a tablet put under the tongue or as a spray, and medical advice on what to do if pain persists (ie. if there is a risk of a heart attack).
• Assessment and treatment for coronary artery disease, including a variety of drug treatments to help open the arteries or treatments such as aspirin and a statin type drug which help to reduce the risk of a heart attack. More invasive treatments to open up the coronary arteries may be recommended especially when there is severe blockage. These are known as coronary revascularisation. The main two types are either coronary artery bypass grafting, or percutaneous transluminal angioplasty.