What is Sudden Cardiac Arrest (SCA)?

Sudden cardiac arrest (SCA) happens when the heart suddenly stops beating because of a problem in its electrical system.


A person's heart will stop beating without warning when they suffer SCA. They will collapse, lose consciousness and look extremely pale.

Causes of SCA

Sudden cardiac arrest strikes without warning, regardless of age, killing 100,000 Brits every year.

It requires immediate treatment to keep blood pumping and to restart the heart to prevent brain damage and death. 

SCA happens because of a problem in the heart’s electrical system. The problem is caused by an abnormal heart rhythm; or cardiac arrhythmia. The most common arrhythmia that leads to SCA is called ventricular fibrillation (VF).

During a case of VF, the heart’s rhythm is so fast that its unable to pump blood to the body and brain effectively. Therefore, defibrillation is urgently needed to prevent death.


Heart Attack vs Sudden Cardiac Arrest

A sudden cardiac arrest is often misunderstood to be the same as a heart attack. They are not the same:

View our SCA and Heart Attack - Understanding the Difference information sheet here.

Sudden Cardiac Arrest facts

How many people die of SCA?

Every year in the UK, 100,000 people die of SCA, making it the nation’s biggest killer. It kills more people than lung cancer, breast cancer and AIDS combined.

Who can suffer SCA?

Anyone, regardless of their age or fitness level, can suffer SCA anywhere, at any time.

What should I do if someone suffers SCA?

  1. Dial 999 for emergency services immediately
  2. While you wait for paramedics, give CPR
  3. Use a defibrillator to restart the heart

Why does every second count?

When someone suffers a sudden cardiac arrest, their heart stops beating. Therefore, their brain is starved of oxygen. The longer the brain is left without oxygen, the more mental and physical damage this can cause to the person, if they survive.

Survival rates drop 7-10% every minute without defibrillation. Quick action can make the difference between life and death.

I’m not trained to use a defibrillator. How could I save a life?

AEDs are designed to guide the user with visual or vocal prompts on when to shock the person and how. The device will not work unless it is placed correctly, therefore it is safe and straightforward to use.

Get in touch for more help and information

+44 (0) 1789 867 501info@heartrhythmalliance.org


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