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People often confuse Sudden Cardiac Arrest (SCA) with Heart Attack. But while both are medical emergencies involving your heart that require immediate treatment and can be deadly, the two heart problems are entirely different.

A heart attack is when blood flow to the heart is blocked, and sudden cardiac arrest is when the heart malfunctions and suddenly stops beating unexpectedly. A heart attack is a “circulation” problem and sudden cardiac arrest is an “electrical” problem.

Heart disease is our biggest killer, and in Australia about 55,000 people have a heart attack each year, of these about 10,000 will die (that’s close to one person every 53 minutes). Estimates suggest between 20,000 to 33,000 people die of a cardiac arrest each year.

What is cardiac arrest?

A Sudden Cardiac Arrest (SCA) occurs when the heart malfunctions and stops beating unexpectedly. It occurs suddenly and often without warning. It is triggered by an electrical malfunction in the heart that causes an irregular heartbeat (arrhythmia). With its pumping action disrupted, the heart cannot pump blood to the brain, lungs and other organs, so they are starved of oxygen. In a matter of just seconds, the victim becomes unresponsive/unconscious and displays no other signs of life such as breathing or movement. Death occurs within minutes if the victim does not receive an emergency first aid response, specifically CPR.

What is a heart attack?

A heart attack occurs when a blocked artery prevents oxygen-rich blood from reaching a section of the heart. If the blocked artery is not reopened quickly, the part of the heart normally nourished by that artery begins to die. The longer a person goes without treatment, the greater the damage. It can also kill you. Symptoms of a heart attack may be immediate and intense (sudden, causing intense pain in the chest or other areas of the upper body (arms, neck, and jaw), shortness of breath, cold sweats, and/or nausea and vomiting). More often though, symptoms start slowly and worsen over days, weeks or even months before the heart attack. The heart usually doesn’t stop beating during a heart attack, unless the heart attack causes a cardiac arrest.

What do they look like?

Sudden cardiac arrests usually occur without warning; if someone has a cardiac arrest they will suddenly become unconscious and show no signs of breathing or a pulse.
Identifying whether you are having a heart attack is more difficult and the Heart Foundation says it takes people an average of six hours to get medical treatment from the first signs of a heart attack.

What is the link?

These two distinct heart conditions are linked. Sudden cardiac arrest can occur after a heart attack, or during recovery. Heart attacks increase the risk for sudden cardiac arrest. Most heart attacks do not lead to sudden cardiac arrest. But when sudden cardiac arrest occurs, heart attack is a common cause. Other heart conditions may also disrupt the heart’s rhythm and lead to sudden cardiac arrest. These include a thickened heart muscle (cardiomyopathy), heart failure, arrhythmias, particularly ventricular fibrillation, and long Q-T syndrome.

What are the causes?

Sudden Cardiac Arrest:

The most common cause of SCA is a life-threatening abnormal heart rhythm called ventricular fibrillation. Ventricular fibrillation occurs when the electrical activity of the heart becomes so chaotic that the heart stops pumping and quivers or ‘fibrillates’ instead. There are various causes of VF, including the following heart-related problems:

- Coronary heart disease
- Heart Attack
- Cardiomyopathy
- Heart valve disease
- Acute Myocarditis

Ventricular fibrillation can also occur if:

- There is a lack of oxygen to the body, for example: choking
- When you are electrocuted
- You have used recreational drugs
- You lose a large amount of blood

Heart Attack:

Most heart attacks are caused by coronary heart disease (CHD). Coronary heart disease is when your coronary arteries (the arteries that supply your heart muscle with oxygen-rich blood) become narrowed by a gradual build-up of fatty material within their walls. If a piece of fatty material breaks off it can potentially cause a blood clot or blockage within the artery, stopping the supply of oxygen-rich blood to your heart muscle.

What should you do?

If you suspect someone has had a cardiac arrest you must act immediately. Your chances of surviving a cardiac arrest decrease by 10 per cent every minute you go without treatment. If you don’t get treatment within 10 minutes, you’re unlikely to survive.
Sudden Cardiac Arrest can be reversible in some victims if it is treated within a few minutes. If you see someone suffering a cardiac arrest, your first point of action should be to dial 000, followed by immediate CPR.  If there are two people there to help, one person should be performing CPR while the other calls 000 and finds an Automatic External Defibrillator (AED). AEDs analyse a victim’s heart and deliver a shock to return it to its normal rhythm. The AED will notify the user when to stop CPR so the patient can be analysed or shocked.

If you think you, or someone else, is having a heart attack, you need to call an ambulance immediately. Sit or lie down while waiting for help to arrive. Do not drive yourself to the hospital.

This informational blog is for general knowledge only and is not to be perceived as medical advice or action. If you are suffering a SCA or Heart Attack, please dial 000 immediately.