How is a heart attack diagnosed?

As soon as ambulance or medical staff arrive they will begin tests to find out what is happening to you. These will include:

  • An ECG (electrocardiogram): to show the amount of damage to your heart muscle and where the damage is. Treatment to restore blood flow and minimise the amount of heart muscle damage (this is called ‘reperfusion’) can be achieved in different ways depending on your ECG readings so it is important that you have an ECG as soon as possible to show exactly what is happening.
  • Blood tests: the main blood test is to measure the amount of troponin in your blood. Troponin is a protein that is released into your blood stream when your heart muscle is damaged, for example during a heart attack. The level of troponin in your blood is increased if you have had a heart attack.

Establishing a diagnosis

Your ECG will show which of the two main types of heart attack you have had

Your ECG will show which of the two main types of heart attack you have had

A heart attack is identified by unusual changes on your ECG reading, that is changes to the pattern of a normal heart beat.

There are two main types of heart attack, based on what changes your ECG shows. These are called:

  • ST-elevation myocardial infarction (STEMI) — the artery supplying an area of the heart muscle is completely blocked and the whole thickness of the heart muscle is affected.
  • Non-ST-elevation myocardial infarction (NSTEMI) — the artery is only partly blocked, so only part of the heart muscle is affected.

Which type of MI you have had will decide what emergency treatment is right for you.

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