What is angina? (other names, angina pectoris, effort angina)

Normal

The heart, like other organs, requires blood to supply it with oxygen and other nutrients. Blood vessels called arteries carry blood from the pumping chamber of the heart around the body. The arteries supplying blood to the heart are the coronary arteries.

Abnormal

A process named 'atherosclerosis' causes damage and narrowing to the arteries, limiting the amount of blood flow. When this occurs in the coronary arteries ("coronary artery disease" or CAD for short), it may cause angina. Usually angina is brought on by physical exertion, which increases the blood required by the heart. If the arterial narrowings are severe enough, angina may be brought on by minimal exertion, emotion or even when resting (unstable angina).

Usually at least a 70% narrowing of an artery is needed to cause symptoms (angina).

Risk factors

Men are at greater risk, increasing age, high blood levels of cholesterol, smoking, high blood pressure, diabetes, obesity, stress and family history of ischaemic heart disease (angina or myocardial infarction).

Genetics

Some people are predisposed to developing coronary disease despite lacking any of the accepted risk factors. The reason for this is uncertain, but these people may have as yet unrecognised risk factors. Possibilities currently under investigation include lipoprotein (a), homocysteine, ferritin, inflammation (caused by infection with a micro-organism Chlamydia pneumoniae) and cholesterol oxidation.

Gender differences

Premenopausal women have a lower risk of angina than men, probably due to the favourable effect of natural oestrogen on the blood lipid profile. After menopause this advantage is lost and the female risk of CAD rapidly approaches that of men of similar age.

What symptoms may I expect?

Angina is typically is brought on by exercise and is a sensation of tightness or pressure behind your breast bone (sternum). It may also be felt in the arm, between the shoulder blades, neck or jaw. Resting relieves it as does medicine (GTN or anginine) placed under the tongue. Other activities that can trigger angina include large meals, becoming excited, or walking into a cold head wind.

What will the doctor look for?

The key feature of angina is that it is usually brought on by increased heart rate with exercise and relieved by rest when the heart slows down.

Indigestion (peptic disease or acid reflux) can also mimic angina but is not typically brought on by exertion.

Causes of chest discomfort that may be difficult to distinguish from angina include rupture of the aorta (the main artery distributing blood from the heart to various parts of the body). In this case the chest pain is usually severe and sudden onset. It is often felt through to between the shoulder blades as well as in the front of the chest.

What investigations will the doctor consider?

Tests & shortcomings

Your doctor will probably ask for an exercise electrocardiograph (treadmill test), where your heart rhythm is recorded before and after walking on a treadmill. This gives an indication whether significant coronary artery narrowings are present.

If your performance on the treadmill is not satisfactory, your doctor may suggest an angiogram. You are lightly sedated for this test which involves passing a thin tube, via a nick in the groin, up near the heart and into the coronary arteries. Dye is then injected to take x-ray pictures of any narrowings and blockages in your coronary arteries.

What treatment options are available?

Lifestyle

All the lifestyle measures will help lessen your angina symptoms and also decrease your risk of having a heart attack:

You must give up smoking. Happily, your risk of a heart attack drops down to the level of a lifelong non-smoker within 2-5 years of you giving up.

Losing weight will directly improve your angina. It will also help reduce your cholesterol level.

A dietician should be consulted to try to help achieve a low fat weight-loss diet. Support and motivation are needed.

Getting fit by regular exercise (do 30 minutes of aerobic exercise such as walking at least three times a week).

Cholesterol, blood pressure and diabetes need to be well-controlled.

You should avoid heavy lifting. Tasks that bring on angina should be attempted more slowly.

Drugs

Aspirin

When the coronary artery wall is damaged by atherosclerosis, clots may form, blocking the artery completely and causing a heart attack. Aspirin thins the blood and helps prevent heart attacks. The usual dose is 75-325 mg each day. Side effects are uncommon but it may cause stomach irritation or bleeding. The benefits usually far outweigh the risks, but you should always discuss starting aspirin with your doctor.

Short-acting nitrates

Glyceryl trinitrate (GTN) is taken under the tongue as a pill or a spray. It works in minutes to relax blood vessels and decrease the heart's workload. It can also be taken before doing activities that cause angina, to prevent an attack. The main side effect is headache. It may also drop your blood pressure, causing you to feel faint (if so you should sit or lie down promptly). If the angina is not relieved by GTN within 20 minutes you should call an ambulance (check this with your doctor).

Beta-blockers

Beta-blockers relieve angina by slowing the heart and making it pump less forcefully. They allow you to do more physical activity before getting angina. People with asthma should not take beta-blockers. Possible side effects include tiredness and sleep disturbance.

Long-acting nitrates

Long-acting nitrates' effectiveness are reduced if your body is exposed to them constantly. Therefore they are usually taken as a once-a-day tablet or a skin-patch applied for only 16 hours each day. They relieve angina. A possible side-effect is headache.

Calcium antagonists

These also relieve angina, allowing you to be more active. They work by relaxing the arteries the heart to pump more efficiently. Possible side-effects include headaches, ankle swelling and constipation.

Surgery or other intervention

If your angina is not satisfactorily controlled through medicines and lifestyle changes, your symptoms may be improved by mechanically unblocking a narrowed artery (angioplasty) or bypassing the blockage (cardiac surgery).

Angioplasty (percutanous transluminal angioplasty, PTCA)

This procedure is similar to an angiogram. It is done by passing thin tubes up from the groin whilst you are lightly sedated. A tiny balloon is passed down the narrowed vessel and inflated to clear the blockage. Usually you can leave hospital the following day, however over the next six months there is a significant chance the opened artery will close again (approximately 30 percent risk).

Increasingly, stents (little tubes), may be blown up and left in the artery to reduce the risk of re-occlusion occurring.

Different drugs are also being researched, which may reduce the risks of occlusions reoccurring.

Cardiac surgery (coronary artery bypass grafting, CABG)

This is open heart surgery where the narrowed and blocked arteries are bypassed with other vessels. You will be in hospital for about one week. It takes some weeks for the chest scar to heal and full recovery to occur.

Prognosis

Angina needs to be taken seriously because it can lead to a heart attack (myocardial infarction) where some of the heart muscle dies. However, we now have very powerful medicines that substantially reduce the risk of this happening (aspirin and statins).

Controversies and uncertainties

It is not known whether hormonal replacement therapy for women will reduce the risk of CAD. The current studies are contradictory.

Elevated homocysteine levels can be reduced by taking folate (sometimes together with vitamin B12 and B6). Whether this reduces the risk of CAD is not known yet.

Vitamins A and C have no role in reducing CAD, they may even increase the risk of CAD. Vitamin E may reduce the risk of heart attack but there still exists some concern over whether it may be harmful. Three further studies are pending.

Getting help

Your doctor, cardiologist or local hospital will be able to help.

The National Heart Foundation of New Zealand, 9 Katrina St, Ellerslie, PO Box 17160, Greenlane Auckland. Ph 571 9191.

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