What is the difference between a heart attack and sudden cardiac arrest?
A heart attack is a blockage in an artery to the heart. The heart is still beating, but blood flow is restricted. Sudden cardiac arrest (SCA) is different: an electrical malfunction disrupts the heart’s normal rhythm and the heart stops pumping blood. You will not find a pulse because there is no longer any blood pressure. CPR must begin immediately.
About 350,000 people suffer an out-of-hospital cardiac arrest each year in the United States, and roughly 9 out of 10 do not survive. But when bystanders start CPR right away and an AED is nearby and used within the first few minutes, the odds change dramatically and survival rates can climb to 40% and higher. Every minute defibrillation is delayed, the chance of survival drops by as much as 10%. Everyone should take a CPR and AED course. Now you can do it online in under an hour. All family members should learn these lifesaving skills. Learn CPR for free here.
So, what are some of the signs of SCA?
- Sudden collapse
- No breathing
- No pulse
- Loss of consciousness
Sometimes there are warning signs and symptoms before the collapse. Here is a short list.
- Chest pains
- Shortness of breath
- Weakness
- Vomiting
What to do when someone collapses from Sudden Cardiac Arrest
Call 9-1-1 immediately, begin CPR, and have someone retrieve the Automated External Defibrillator (AED) if one is available. If you do not know how to perform CPR, just give chest compressions (also known as Hands-Only CPR), hard and fast in the center of the chest, at a rate of 100-120 compressions per minute. If you are trained in CPR, deliver rescue breaths as well to keep oxygen flowing and help protect the brain. The American Heart Association’s 2025 Guidelines put renewed emphasis on compressions with breaths as part of a single Chain of Survival for both adults and children.
If an AED is available, someone should continue CPR while the AED is being set up. Once the pads are attached, the machine will check for a heart rhythm and advise whether a shock is needed. Just follow the simple voice instructions. An AED is designed so anyone can use it.
