Angina - Diagnosing angina

If you see your GP after experiencing chest pain, they'll probably ask about the pattern of your symptoms – for example, if you've noticed any particular triggers.  

Your GP will then assess whether you're at increased risk of developing atherosclerosis. This is where the arteries become clogged by fatty substances, which can lead to the symptoms of angina.

As part of the assessment you'll have:

• blood pressure tests
• your weight and waist size measured
• blood tests to measure the amount of cholesterol and glucose (if you are diabetic) in your blood and also to determine how well your liver is working
• a urine test to determine how well your kidneys are working

Tests are necessary because some angina medications aren't suitable for people with liver or kidney disease.

You're also likely to discuss whether you smoke, if you drink and how much, whether you have a high-fat diet, and any family history of heart disease.

Further tests

If angina is suspected, you'll usually be referred to a specialist cardiology department or clinic for diagnosis and to assess your risk of having a heart attack or stroke in the future.

You may be prescribed a medication called glyceryl trinitrate to provide immediate relief for any angina while you wait to see a specialist (see treating angina for more information).

The assessment involves a series of tests that are explained below.

Electrocardiogram (ECG)

An ECG records the rhythms and electrical activity of your heart. A number of electrodes (small metallic discs) are placed on your arms, legs and chest. The electrodes are connected to a machine that records the electrical signals of each heartbeat.

An abnormal ECG reading may indicate that the muscles of your heart aren't receiving enough blood.

Exercise tolerance test (ETT)

An ETT is similar to an ECG, but it's carried out when you're exercising, usually on a treadmill or an exercise bike.

An ETT can be used to measure how much exercise your heart is able to tolerate before the symptoms of angina are triggered. This information is useful for assessing how severe your angina is likely to be.

Myocardial perfusion scintigraphy (MPS)

An MPS is an alternative test to an ETT used if a person is unable to exercise or when the results of an ETT are unclear.

MPS involves injecting a small amount of a radioactive substance into your blood. A special camera, known as a gamma camera, is used to track the substance as it moves through your blood vessels and into your heart. This allows healthcare professionals to determine how well blood is reaching your heart.

MPS is usually carried out both at rest and when you're exercising. If you're unable to exercise, medication can be used to replicate the effects of exercise on your heart.

Coronary angiography

A coronary angiography is a test to identify whether your coronary arteries are narrowed and determine how severe any blockages are.

During an angiography, a thin, flexible tube called a catheter is passed into a vein or artery in your groin or arm, and X-rays are used to guide it into your coronary arteries. A dye is injected into the catheter to highlight the arteries supplying blood to your heart. A number of X-ray images (angiograms) are taken, which highlight any blockages.

Coronary angiographies carry a small risk of serious complications, such as a stroke or a heart attack, which is estimated to be around 1 in 1,000. Although this risk is small, healthcare professionals are usually unwilling to perform an angiogram unless the benefits of the procedure outweigh potential risks.

Therefore, it's likely you'll only be referred for a coronary angiogram if:

• the diagnosis of angina remains unclear
• your angina symptoms persist despite treatment and/or you're thought to be at significant risk of having a heart attack or stroke and surgery is being considered

Unstable angina

If it's thought you may have unstable angina, you'll be admitted to hospital. Depending on the severity of your symptoms, you may be placed in a general ward or in the coronary care unit (CCU).

You'll be given an ECG as soon as you arrive at hospital to quickly assess whether your heart has been significantly damaged.

Blood tests will also be carried out to help identify increased enzyme levels (these are released when the heart is damaged). A coronary angiography may also be performed to assess the size and location of the blockage in your coronary artery.

Treatment may be started urgently, before all of the test results are known, to prevent serious complications arising from unstable angina.

Global Registry of Acute Cardiac Events (GRACE)

After receiving suitable treatment for unstable angina, doctors will want to assess how likely you are to develop another angina attack, or possibly the symptoms of a heart attack, in the next six months. The outcome will have an important bearing on your recommended treatment plan.

GRACE is a widely used method of assessing the risk of further heart problems occurring. GRACE is a scoring system based on factors such as:

• your age
• the number of times your heart beats every minute
• your blood pressure
• how much of a substance called creatinine is present in your blood – higher-than-expected levels can be a sign of heart damage
• whether you have any signs and symptoms of heart failure, such as excess fluid inside your lungs

Your GRACE score provides a relatively accurate predictor of your risk of developing further heart problems. The score can range from very low (less than 1 in 65) to the highest (more than 1 in 10).

Surgery is usually recommended as a precaution if you have at least a 1 in 33 chance of developing further problems.

Read more about treating unstable angina.