Heart attack - Diagnosis 

Diagnosing a heart attack 

Angiogram

Every year, 61,000 coronary angioplasties are carried out in the UK. If you have angina or have had a heart attack, your doctor may suggest the procedure. Dr Stephen Brecker explains what's involved.

Media last reviewed: 14/11/2013

Next review due: 14/11/2015

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If a heart attack is suspected, you should be admitted to hospital immediately. You will usually be admitted to an acute cardiac care unit (ACCU), or directly to the cardiac catheterisation unit, to confirm the diagnosis and begin treatment.

Electrocardiography

An electrocardiogram (ECG) is an important test in suspected heart attacks. It should be carried out within 10 minutes of being admitted to hospital.

An ECG measures the electrical activity of your heart. Every time your heart beats, it produces tiny electrical signals. An ECG machine records these signals onto paper, allowing your doctor to see how well your heart is functioning.

An ECG is painless and takes about five minutes to perform. During the test, electrodes (flat metal discs) are attached to your arms, legs and chest. Wires from the electrodes are connected to the ECG machine, which records the electrical impulses.

An ECG is so important because:

  • it helps confirm the diagnosis of a heart attack
  • it helps determine what type of heart attack you have had, which will help determine the most effective treatment

Types of heart attack

Heart attacks can be classified by a measurement known as the ST segment. The ST segment is an electrical measurement recorded by an ECG. It corresponds to the level of damage inflicted on the heart.

The higher the ST segment, the greater the likely damage.

Acute coronary syndrome

A heart attack is a form of acute coronary syndrome (ACS), where there is a significant blockage in the coronary arteries.

There are three main types of ACS:

  • ST segment elevation myocardial infarction (STEMI)
  • non-ST segment elevation myocardial infarction (NSTEMI)
  • unstable angina

The three types are described in more detail below.

ST segment elevation myocardial infarction (STEMI)

A STEMI is the most serious type of heart attack, where there is a long interruption to the blood supply. This is caused by a total blockage of the coronary artery, which can cause extensive damage to a large area of the heart.

A STEMI is what most people think of when they hear the term "heart attack".

Non-ST segment elevation myocardial infarction (NSTEMI)

An NSTEMI can be less serious than a STEMI. This is because the supply of blood to the heart is only partially, rather than completely, blocked.

As a result, a smaller section of the heart is damaged. However, NSTEMI is still regarded as a serious medical emergency.

Unstable angina

Unstable angina is the least serious type of ACS although, like NSTEMI, it is still regarded as a medical emergency.

In unstable angina, the blood supply to the heart is still seriously restricted, but there is no permanent damage, so the heart muscle is preserved.

Other tests

A number of other tests can be used to assess the state of your heart and check for related complications. However, because heart attacks are medical emergencies, some tests are usually only carried out once your initial treatment has begun and your condition has been stabilised.

Blood tests

Damage to your heart from a heart attack causes certain proteins to slowly leak into your blood. Enzymes are special proteins that help regulate chemical reactions that take place in your body.

If you have had a suspected heart attack, a sample of your blood will be taken so it can be tested for these heart proteins (known as cardiac markers). Your protein levels will be measured through a series of blood samples taken over the course of a few days.

This will allow damage to your heart to be assessed, and also help determine how well you are responding to treatment.

Read more information about blood tests.

Chest X-ray

A chest X-ray can be useful if diagnosis of a heart attack is uncertain and there are other possible causes of your symptoms, such as a pocket of air trapped between the layers of your lungs (pneumothorax).

A chest X-ray can also be used to check whether complications have arisen from the heart attack, such as a build-up of fluid inside your lungs (pulmonary oedema).

Echocardiogram

An echocardiogram is a type of ultrasound scan that uses sound waves to build up a picture of the inside of your heart.

This can be useful to identify exactly which areas of the heart have been damaged and how this damage has affected your heart’s function.

Coronary angiography

Coronary angiography can help determine whether a blockage or narrowing has occurred in the coronary arteries and, if so, to locate the exact location of the blockage or narrowing.

The test involves inserting a thin tube, known as a catheter, into one of the blood vessels in your groin or arm. The catheter is guided into your coronary arteries using X-rays.

A special fluid, known as a contrast agent, is pumped through the catheter. This fluid shows up on X-rays, and studying how it flows around and through your heart can help locate the site of any blockage or narrowing.

A coronary angiogram is often performed just before surgery, as the results can help guide the efforts of the surgeon. Read our page on treating a heart attack for more information.




Page last reviewed: 13/06/2014

Next review due: 13/06/2016

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The 1 comments posted are personal views. Any information they give has not been checked and may not be accurate.

Ravin Sobnack said on 26 January 2012

I am rather disturbed that the nurse rather than the GP insisted that I have an ECG the same day (Friday) after I complained of very swollen ankles, shortness of breaths as going up the stairs and several episodes of near-fainting (without diziness) incidents after standing too long at the kitchen worktop. The GP was shown the ECG trace on Friday and they both came out to (I presume) identify me and got an appointment for Wednesday following week. THAT was when I was told I have had an MI (myocardial Infarction), without any signs of urgency. Shocked that MI was not receiving immediate attention, I went to A&E at the RLH and got seen and reassured. I have already had a myocardial stress perfusion study that (luckily) shows so significant MI. I will be seeing my cardiologist next Thursday, when, I hope I'll find if all is well.

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