Cardiac Arrest vs. Heart Attack: Understand the Difference

While the terms are often confused, cardiac arrest and heart attack are different conditions. They have different causes, treatments, and potential outcomes. Both, however, are emergencies that require immediate medical attention.

Sudden cardiac arrest is an electrical problem in the heart that causes the heart to stop beating. Heart attack is a circulation problem blocking blood flow to the heart. Time is critical for both types of conditions—cardiac arrest can cause death within minutes if the person doesn’t receive treatment. Heart attack causes damage over time. The longer it’s untreated, the more damage the heart muscle suffers. Heart attacks can also trigger a cardiac arrest.

Michelle O’Donoghue, MD, MPH, describes the difference between cardiac arrest and heart attack, how to recognize the symptoms of each, and how to respond in an emergency. Dr. O’Donoghue is a Mass General Brigham Heart and Vascular Institute cardiologist and leader in heart disease research. She treats patients at Brigham and Women’s Hospital.

What is cardiac arrest?

Cardiac arrest, also called sudden cardiac arrest, is an emergency condition caused by an electrical problem in the heart. The problem causes arrhythmia (irregular heart rhythm) which causes the heart to stop beating.

Symptoms of cardiac arrest

When a person has a cardiac arrest, they become unresponsive or lose consciousness. They stop breathing or can only gasp for air, and their pulse stops.

Cardiac arrest often starts suddenly, without any warning signs or symptoms. It’s important for you to learn the signs of cardiac arrest. As a bystander, you can save a life by recognizing the signs of a cardiac arrest, starting CPR, and calling 9-1-1.

Cardiac arrest can look like:

• A sudden collapse
• Jerking movements, similar to a seizure
• Not breathing or agonal breathing, where the person is gasping, breathing irregularly, or taking very short, shallow breaths

Cardiac arrest requires immediate help. If you see someone in cardiac arrest, start CPR, call 9-1-1, and find an automated external defibrillator (AED) if there is one nearby.

“Don’t wait for the ambulance to help someone who doesn’t have a pulse,” notes Dr. O’Donoghue. “Doing chest compressions imperfectly is always more helpful than doing nothing.”

Cardiac arrest causes death within minutes if not treated.

What happens during a heart attack?

A circulation problem blocking blood flow to your heart causes a heart attack, also called a myocardial infarction. A fatty deposit rupture, blood clot, or something else blocks the blood flow to the heart, reducing the amount of oxygen getting to the heart muscle. As your heart receives less or no blood flow, heart tissue starts to die. The longer it’s left untreated, the more damage a heart attack will cause. A heart attack can also trigger a cardiac arrest.

Symptoms of heart attack

Signs of a heart attack vary, but the most commonly reported symptoms are:

• Chest pain, chest discomfort or chest heaviness
• Pain that radiates to the neck or left arm
• Difficulty breathing or shortness of breath
• Cold sweat
• Nausea

In addition to the "classic" signs of a heart attack, you might experience these less common heart attack symptoms:

• Anxiety
• Dizziness
• Fatigue
• Insomnia

Heart attack symptoms vary from person to person, and they also vary by sex. Women and people assigned female at birth (AFAB) are less likely to have chest pain and more likely to report shortness of breath, fatigue, and insomnia compared to men or people assigned male at birth (AMAB).

Symptoms usually start suddenly but can start hours or even days before a heart attack happens. 

Heart attack is an emergency condition. If you’re experiencing symptoms of a heart attack, don’t hesitate to call 9-1-1. Emergency medical services (EMS) can start treatment in the ambulance on the way to the hospital, improving outcomes.

“When in doubt, call 9-1-1 for any symptoms of a heart attack,” Dr. O’Donoghue says. “Don’t wait for symptoms to improve, and don’t drive yourself to the hospital. Time is critical, and we’d rather a false alarm than a missed emergency.”  

Left untreated, a heart attack can cause severe heart damage and death within minutes to hours.

Can heart attack cause cardiac arrest?

Heart attack can lead to cardiac arrest, either right away or during recovery. Once the heart is damaged by heart attack, it’s more likely to suffer an electrical problem that causes cardiac arrest.

Which is more serious, cardiac arrest or heart attack?

Cardiac arrest is a more serious condition, causing death in minutes if not treated by bystanders. However, both conditions require immediate medical attention and can cause death if not treated. 

Heart attack causes long-term heart damage and complications the longer you go without treatment.

Can you survive cardiac arrest?

Cardiac arrest causes death within minutes if not treated right away. The American Heart Association notes that you can double or even triple someone’s chance of survival from cardiac arrest by doing CPR.

Without bystanders doing CPR and calling 9-1-1, a victim of cardiac arrest will die. People who have cardiac arrest outside of a hospital survive about 10% of the time, and only when bystanders call 9-1-1, start CPR, and use an AED if one is available. 

Can you survive a heart attack?

When treated quickly by calling 9-1-1 and getting emergency care, you can survive a heart attack. A 2022 study showed 1-year survival rates of almost 90% and a 7-year survival rate of 74%.

Heart attack causes damage to the heart muscle, so you may experience complications and ongoing heart issues. Your cardiologist treats your heart attack through medicine, procedures, and cardiac rehabilitation.

Heart attack recovery takes time and depends on your treatment plan, the severity of the attack, the extent of the damage, and your health before the attack.

Emergency actions for cardiac arrest vs. heart attack

The most important thing to do in case of cardiac arrest or heart attack is to call 9-1-1.

For cardiac arrest, here’s what you can do:

• Check for responsiveness.
• Shout for help.
• Call 9-1-1 to get emergency medical services.
• Begin CPR and continue until EMS staff arrive.
• Get an automated external defibrillator if one is available. Use it as soon as it arrives.
• If two people can help, one should begin CPR right away while the other calls 9-1-1 and finds an AED.

For heart attack symptoms:

• Call 9-1-1.
• Chew an aspirin, if you’re not allergic to it, while waiting for EMS to arrive.
• If you already have a heart condition and have been prescribed nitroglycerin by your cardiologist, take it now.
• If you’re a bystander and the person experiencing the heart attack stops breathing or doesn’t have a pulse, start CPR and use an AED if one is available.

If an AED is available, follow the instructions on the device–they are written on the box, and the machine plays voice prompts out loud. 

When you call 9-1-1, the emergency dispatcher can also talk you through the steps to do CPR and use the AED. Consider taking a CPR and emergency response class to be prepared in case you ever need to help in an emergency.

You can save a life in an emergency by knowing the different signs and symptoms of cardiac arrest and heart attack and how to respond in an emergency.

“Cardiac arrest and heart attacks are life-threatening, scary situations,” Dr. O’Donoghue says. “Bystanders are critical to emergency care for these conditions. Learn the signs and don’t be afraid to jump into action to help.”