Cardiac Arrest vs. Heart Attack: What's the Difference?

People often use the terms heart attack and cardiac arrest interchangeably, but they are very different medical conditions. What’s common between them is that they are both life-threatening events. If someone is suffering from a heart attack or sudden cardiac arrest, every minute counts. Fast action can save lives. Please continue reading to learn more about heart attacks and cardiac arrests, including their symptoms and what to do if you suspect one of these events is occurring.

What is a sudden cardiac arrest? Why do cardiac arrests happen?

The heart has a built-in electrical system that keeps it beating at a steady pace. Any problem with this system can lead to a dangerously erratic and fast heart rhythm—this is called an arrhythmia. An arrhythmia can cause the heart muscle to quiver and stop beating. Conditions such as high blood pressure, high cholesterol, and previous heart attacks can cause electrical problems in the heart. 

A sudden cardiac arrest is an electrical malfunction of the heart that frequently occurs without warning. The electrical problem causes an arrhythmia (irregular heartbeat) that disrupts the normal pumping action of the heart. The heart stops beating and blood supply to vital organs such as the brain and lungs is cut off. The victim loses consciousness within seconds and has no pulse. Death can occur within minutes if a person does not receive immediate treatment for sudden cardiac arrest.

What is a heart attack? 

The heart is a muscular organ that pumps blood to every organ in the body. It also provides a blood supply to itself through the coronary arteries. Two major coronary arteries and their branches carry blood flow to the heart.

A myocardial infarction (heart attack) occurs when an artery bringing oxygen-rich blood to a part of the heart muscle becomes blocked. This can happen if a cholesterol plaque in the artery ruptures and forms a blood clot, causing complete blockage of the artery. If the artery is not unblocked quickly, the part of the heart muscle it supplies begins to die. Without treatment, this can lead to permanent damage. The amount of damage that occurs from a heart attack depends on how quickly a person receives treatment. 

What’s the difference between a heart attack and cardiac arrest?

A heart attack is a circulation (blood flow) problem and a cardiac arrest is an electrical (heart rhythm) problem. Unlike what happens during a sudden cardiac arrest, the heart does not completely stop beating during a heart attack.

However, a heart attack and cardiac arrest are not completely unrelated. A heart attack can create problems and increase the risk of sudden cardiac arrest. A cardiac arrest can occur soon after a heart attack or during recovery. Most heart attacks do not lead to cardiac arrest. But in people who suffer sudden cardiac arrests, heart attacks are a common cause. 

How do you know if you are having a heart attack or cardiac arrest?

Symptoms of a heart attack can be sudden and intense. However, oftentimes, heart attack symptoms can start slowly and persist for hours, days, or even weeks. While circulation is weak during a heart attack, there is still some blood flow to the heart and it continues pumping blood to vital organs like the brain. Therefore, the person stays awake and may experience symptoms of a heart attack such as chest pain that radiates to the arm, shortness of breath, difficulty breathing, sweating, and weakness. 

People suffering from a sudden cardiac arrest often lose consciousness within minutes with little to no warning. This happens because the heart stops beating and there is no blood flow to the brain. More than half of all people who suffer a sudden cardiac arrest experience no preceding symptoms. However, some people may have chest pain, shortness of breath, dizziness, bluish discoloration of the face, and report feeling unwell just before a sudden cardiac arrest.

What to do if someone is having a heart attack or cardiac arrest?

If you suspect someone is having a heart attack, call 911 or the emergency response number in your country immediately. Emergency medical services (EMS) can start treatment en route to the hospital and ensure the person sees a doctor and gets treatment faster once they reach the hospital (rather than arriving at the hospital by private car).

Sudden cardiac arrest is reversible if it is treated within the first few minutes. If you suspect someone is having a cardiac arrest (sudden loss of consciousness and no pulse), call 911 and start CPR immediately until emergency medical services arrive. Hands-only CPR can double or triple a person’s chances of survival. If an automated external defibrillator (AED) is available, use it if you know how or as soon as the EMS arrives.

Can you have cardiac arrest without a heart attack?

Sudden cardiac arrest can happen without a heart attack. It can even happen in people with no known heart disease. But a life-threatening arrhythmia and cardiac arrest usually develop in people with pre-existing (possibly undiagnosed) heart conditions such as coronary artery disease (clogging of the coronary arteries with cholesterol and other deposits), cardiomyopathy (enlarged, thickened, or stretched heart muscle walls), valvular heart disease (leaking heart valves), and congenital heart disease (heart defects present since birth).

Is a heart attack or cardiac arrest worse?

A heart attack occurs in about 800,000 Americans each year. Of these, around 600,000 are first heart attacks and 200,000 are recurrent attacks in people who have had a heart attack before. With advances in medicine, today, more than 90% of people survive a heart attack.

Sudden cardiac arrest is a leading cause of death in the United States and worldwide. More than 300,000 sudden cardiac deaths occur in the U.S. annually and 95% of incidents are fatal. During a sudden cardiac arrest, the heart stops beating. If you see someone in cardiac arrest, call 9-1-1 right away and then start CPR. Keep doing CPR until medical professionals arrive. There is irreversible brain damage and death if the victim is not treated within the first 4-5 minutes. After the first 3 minutes of collapse, the chances of survival decline rapidly with each passing minute. Death is unavoidable if the person does not receive defibrillation within 5-6 minutes. Given this, you can say that a sudden cardiac arrest is worse or more dangerous than a heart attack, which does not require CPR. However, both are emergencies that require immediate medical attention.

References:

1. https://www.heart.org/en/health-topics/heart-attack/about-heart-attacks/heart-attack-or-sudden-cardiac-arrest-how-are-they-different
2. https://www.mayoclinic.org/diseases-conditions/sudden-cardiac-arrest/symptoms-causes/syc-20350634
3. https://www.aerjournal.com/articles/sudden-cardiac-death-and-arrhythmias
4. https://www.cdc.gov/heartdisease/facts.htm
5. https://www.health.harvard.edu/healthbeat/how-heart-attacks-became-less-deadly