Pain in the chest, usually brought on by exertion and relieved by rest
Angina is chest pain that originates in the heart muscle during physical activity and is quickly relieved by rest. The pain is due to an inadequate supply of blood to the heart muscle. Angina affects both sexes but is less common in women under 60 because the hormone oestrogen protects against it. This protection gradually disappears when levels of oestrogen drop after the menopause.
Over the last 40 years, angina has become progressively less common in western Europe, mainly due to more healthy lifestyles. At the same time, treatment with drugs and surgery has also improved the outlook for people who have the condition.
The most common cause of angina is coronary artery disease, a narrowing of the arteries that supply the heart muscle. This narrowing is usually the result of fatty deposits building up on the inside of the artery walls (see Atherosclerosis). The blood flow through the arteries may be sufficient for the heart while it is at rest but becomes inadequate during exertion. If the supply of oxygen-rich blood is insufficient, the heart muscle is starved of oxygen and toxic substances build up in the heart muscle, causing a constrictive, cramp-like pain. People who have a high blood cholesterol level (see Hypercholesterolaemia), persistently high blood pressure (see Hypertension), or diabetes mellitus have an increased risk of developing atherosclerosis and angina. Having a close relative with the disorder also increases the risk of angina, as does smoking.
Angina can also be caused by temporary spasm of the coronary arteries, in which the arteries narrow for a short time, or by a damaged heart valve that causes a reduction in the blood flow to the heart muscle (see Aortic stenosis). Occasionally, angina is caused or made worse by anaemia, in which the ability of the red blood cells to carry oxygen is impaired, thus reducing the supply of oxygen to the heart.
The chest pain of angina varies from mild to severe. It usually starts during exertion and is relieved after a short rest. The features of angina are:
A dull, heavy, constricting sensation in the centre of the chest.
A discomfort that spreads into the throat and down one or both arms, more often the left arm.
Angina usually occurs predictably at a particular level of exertion. For example, if you regularly walk uphill or climb stairs, it will develop at about the same stage of the activity each time. Angina caused by outdoor exertion often occurs more rapidly in cold or windy weather.
If you experience this type of chest pain for the first time or if your angina becomes more frequent, more severe, or develops at rest, you should contact your doctor immediately. Worsening angina can be a warning that a blood clot has formed in the coronary artery, which may completely block it and cause a heart attack (see Myocardial infarction). A prolonged and very severe attack of angina may be due to a heart attack.
Your doctor will usually make a diagnosis of angina from your symptoms. However, in some circumstances it may be difficult for your doctor to be certain that the pain is actually angina and is not caused by another problem such as gastro-oesophageal reflux disease or pain from the chest wall.
Your doctor will measure your blood pressure to see if you have hypertension. He or she may also arrange for you to have blood tests to check for anaemia or raised cholesterol levels. You will probably have an ECG to monitor the electrical activity of the heart at rest and exercise testing as a comparison. The ECG may show no abnormalities, but the exercise test will usually be abnormal if you have angina. The ECG may confirm that you have had a heart attack. If the tests confirm that there is a significant problem with blood flow to the heart, you may need coronary angiography, in which dye is injected into the coronary arteries so that narrowed areas can be detected on an X-ray.
The treatment of angina depends on its severity. Drugs are used to relieve acute episodes of pain and also to reduce the number and severity of attacks. Drug treatment of an acute attack usually includes nitrate drugs to widen coronary arteries. Fast-acting nitrates can be administered in the form of a spray or soluble tablets. Longer-acting nitrates can be taken on a regular basis to prevent attacks from occurring. Other drugs that may be used to widen the coronary arteries and improve blood flow to the heart include calcium channel blockers. In addition, drugs may be used to reduce the heart’s need for oxygen, such as beta blockers or ivabradine. Doctors also advise a daily low dose of aspirin (see Drugs that prevent blood clotting) because this makes the blood less sticky and reduces the risk of clots forming in an artery. If there is an underlying disorder contributing to angina, such as aortic stenosis, hypertension, or diabetes mellitus, it will be treated.
Lifestyle changes can prevent worsening of angina and increase the level of exercise that you can achieve without experiencing pain. It is imperative that you stop smoking; cutting down is not sufficient. A diet that is low in saturated fat is important, and, if necessary, you should try to lose weight (see Controlling your weight). You may also be prescribed drugs to lower your blood cholesterol level (see Lipid-lowering drugs), even if it is within the normal range, because these drugs have been shown to slow down the progress of coronary artery disease. You should take as much regular exercise as you can within the limits prescribed by your doctor. Walking as little as 1.5–3 km (1–2 miles) every day can be enough to reduce the risk of a fatal heart attack.
If angina becomes more severe in spite of drug treatment, your doctor may advise an invasive procedure to improve blood flow to the heart, such as coronary angioplasty. Usually, a stent (a tubular scaffold device) is inserted to help keep the artery open, although this may not be possible if the artery is very narrow or convoluted. In about 15–20 per cent of people who have coronary angioplasty and stenting, the artery narrows again within about 6 months. However, new stents have been developed that are coated with slow-release drugs that reduce the risk of arterial renarrowing (called drug-eluting stents). If you have had a conventional stent inserted, you may be prescribed clopidogrel, an antiplatelet drug that makes the blood less sticky, thereby reducing the chance of a clot forming at the site of the stent. If you have had a drug-eluting stent inserted, you may be prescribed both clopidogrel and aspirin.
Angioplasty and stenting is rarely suitable if several coronary arteries are narrowed, in which case you will probably be advised to have a coronary artery bypass graft, in which an artery inside the chest wall or a vein taken from a leg is used to bypass the diseased areas in the arteries. Coronary artery bypass grafting is a major surgical procedure that requires a brief stay in an intensive therapy unit because it carries a small risk of complications. You will need 2–3 months of convalescence.
The outlook depends on the extent of coronary artery disease. If you have mild angina, the outlook is good provided that you make sensible lifestyle changes and follow treatment advice. People often experience no further symptoms once treatment has started, and many are able to live a normal life apart from some restrictions on exercise. If you are otherwise in good health, you have a 1 in 2 chance of surviving for at least 10–12 years. If the arteries are badly damaged, however, the outlook is less favourable.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.