Cardiac Arrest

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A cardiac arrest (sudden cardiac death) occurs when the heart suddenly stops beating. It is often triggered by an electrical malfunction in the heart that causes the heart muscle to beat ineffectively.

As soon as the heart stops beating, blood can no longer flow to the brain, heart and lungs. A person in cardiac arrest will be unconscious and will stop breathing or will not be breathing normally (they can make gasping noises or may be breathing irregularly).

Urgent treatment is required to get the blood moving around the body and try to restart the heart.

If you witness a cardiac arrest call Triple Zero (000) immediately.

What to do

Make sure it is safe to approach. Check for any response from the victim. Tilt the head back, lift the chin and check breathing.

If someone is not conscious or isn't breathing normally, it is likely they are having a cardiac arrest. They need urgent help!

The Heart Foundation supports the “restart a heart” campaign which recommends the following steps for a suspected cardiac arrest:


  • Call Triple Zero (000) immediately and ask for an Ambulance
  • Don’t hang up! The Triple Zero (000) Call-taker will stay on the phone until an Ambulance arrives and may need to ask you more questions
  • The Call-taker will talk you through what to do


  • Place the heel of your hand in the centre of the chest and the other hand on top
  • Push hard and fast in the centre of the chest
  • Push to a rate of 100-120 compressions every minute (2 compressions every second) or push to the beat of “Staying Alive”.
  • Push hard. You can’t do any harm, but you may save a life.
  • If you have learned how to do it, provide 2 rescue breaths between every 30 compressions, otherwise push the chest continuously.


  • If a defibrillator (also known as AED) is available, switch it on immediately - it will tell you what to do.
  • You do not need any training to use an AED. Learn more

Cardiopulmonary resuscitation (CPR)

Cardiopulmonary resuscitation (commonly called CPR) uses chest compressions to squeeze the heart and push blood around the body. CPR should be started without delay for anyone who is not conscious and not breathing normally.

Chest compressions can be done on their own (without mouth-to-mouth breathing) and this is known as hands-only CPR. Chest compressions are essential in all cardiac arrest scenarios. If you are not trained in mouth-to-mouth breathing, or not confident to do mouth-to-mouth, hands-only CPR is recommended. 'Mouth-to-mouth' breathing (also called rescue breaths) can be used to add extra oxygen to the body.

Using a defibrillator

A defibrillator (also known as automated external defibrillator, or AED) can apply a controlled electric shock to try to restart the heart.

There are AEDs in many buildings and public places. They can be used by anyone, with or without training, as they provide voice prompts and pictures to guide you through what to do. 

If needed, an AED will deliver a controlled electric shock to try to 'restart' the heart. It will not deliver a shock if it is not required and you will not do any harm by putting an AED on someone who is unconscious. The AED will also tell you when to pause and restart CPR - just follow the voice instructions. You can't do any harm, but you may save a life!

When CPR and an AED are used in the first few minutes after a cardiac arrest, the chances of survival are the greatest.

Cardiac arrest often occurs without warning and can happen anywhere and at any time. It can affect people of all ages, including young people who are otherwise fit and healthy. People may have a cardiac arrest at their workplace, school, sporting club or in their own home. That's why it is important for everyone to know what to do. The person needing life-saving action may be someone you know!

Cardiac arrest versus heart attack

A cardiac arrest (sudden cardiac death) is different to a heart attack. The symptoms and management are also different.

A person experiencing a heart attack will usually be alert and breathing. In a cardiac arrest, the person will not be conscious or breathing normally, so they will need immediate help by calling Triple Zero (000), starting chest compressions and using a defibrillator. A heart attack can sometimes deteriorate to cause an electrical malfunction and then cardiac arrest, and in all these cases treatment for a cardiac arrest is required.

In people with coronary heart disease, cardiac arrest is often preceded by chest pain and other warning signs of heart attack.  Prompt response to chest pain may avert cardiac arrest and sudden cardiac death in people suffering a heart attack. 


There is no national registry of sudden cardiac arrest, but it is estimated that 25,000 people suffer a cardiac arrest outside of hospital in Australia every year. Currently only 10% of these people survive.

Currently less than half of people who suffer a cardiac arrest in the community have someone step in to do CPR or use an AED before an ambulance arrives. For every minute that passes without CPR and AED the chance of survival drops by 10%.

When people step in and take action in the first few minutes after someone collapses the chance of survival dramatically increases.


While cardiac arrest can be caused by heart conditions, it can also be caused by trauma, such as a fall or car accident, breathing conditions and allergic reactions. Sometimes there is no identifiable cause.

Useful websites

More information

Contact the Heart Foundation Helpline on 13 11 12 to speak to one of our qualified health professionals who can provide free personalised information or email