Cardiac Arrest vs. Heart Attack: What's the Difference?
April 30, 2025 - Katie McCallumYour heart is one of the most important organs in your body — if not the most important.
It pumps blood to every other organ, providing the constant supply of oxygen and nutrients these systems need to function. This process is also involved in removing harmful metabolic waste, like carbon dioxide.
If the heart stops working properly, as is the case with cardiac arrest, or it stops receiving a sufficient amount of blood, as is the case with heart attack, the rest of the body starts shutting down.
Dr. Kevin Lisman, a cardiologist at Houston Methodist, points out that while the terms heart attack and cardiac arrest are frequently used as synonyms, they're unique conditions that should be understood distinctly. Here's everything you need to know about heart attack, cardiac arrest, how to prevent each and when to seek medical attention.
What is a heart attack?
A heart attack, also called myocardial infarction, happens when blood flow is reduced or completely cut off, causing damage to heart tissue. The narrowing or blockage of blood vessels is caused by plaque buildup of cholesterol and fat. As the heart muscle deteriorates, blood flow to the rest of the body becomes disrupted.
Heart attack symptoms include:
- Chest pressure (or tightness) that comes and goes
- Increasing shortness of breath with activity
- Unusual fatigue
- Cold sweats
- Feeling lightheaded
- Nausea
- Pain in your jaw, arm, neck or back
- Vomiting
Some may be more subtle, while others may increase in intensity, and it's important not to downplay symptoms since a heart attack is life-threatening medical emergency.
What is cardiac arrest?
"Cardiac arrest is when the heart suddenly develops a severe arrhythmia, causing it to beat inefficiently," explains Dr. Lisman.
An arrhythmia is an issue with the heart's electrical system that affects the rhythm at which the heart beats. Not all arrhythmias are immediately harmful. But some, including ventricle fibrillation (V-fib) and ventricular tachycardia, can develop suddenly and lead to cardiac arrest. (Related: What Are Heart Palpitations & When to Worry)
"These types of irregular rhythms disrupt the heart's ability to pump blood effectively," explains Dr. Lisman. "When the brain, lungs and other vital organs aren't getting adequate blood flow, it leads to loss of consciousness and breathing, as well as organ damage and injury."
Unsurprisingly, cardiac arrest is also a medical emergency — life-threatening if not treated immediately. Cardiac arrest is treated by shocking the heart back into a normal rhythm using a defibrillator device.
"In the meantime, though, anyone can administer life-saving care by performing cardiopulmonary resuscitation (CPR)," says Dr. Lisman. "It's why I strongly recommend everyone take a course on how to provide basic life support."
Key differences between cardiac arrest and heart attack
Where cardiac arrest is an electrical problem that affects blood flow to every organ in the body, heart attack is an issue with blood flow to the heart, specifically, that occurs when the arteries become blocked.
Heart attack itself is almost always caused by coronary artery disease (CAD), a common heart condition in which the coronary arteries narrow over time as a result of plaque buildup, a process called atherosclerosis. (Related: Can You Reverse Coronary Artery Disease?)
Cardiac arrest, on the other hand, can actually be caused by heart attack. But a person with no known heart issues can also experience sudden cardiac arrest. "There are genetic disorders that can make a person more prone to arrhythmias and, therefore, cardiac arrest," explains Dr. Lisman. "For instance, cardiac channelopathy disorders affect how electricity transverses through heart, setting a person up for arrhythmias."
How one can lead to another
"By far and away, the most common cause of cardiac arrest is heart attack," explains Dr. Lisman. "As blood flow to the heart is reduced, the injury experienced can set off cardiac arrest by triggering one of these dangerous rhythms."
This means both cardiac arrest and heart attack are best prevented by taking steps to reduce your risk of developing coronary artery disease or working with your doctor to establish an effective plan for managing the condition if you already have it.
Living a healthy lifestyle — eating a well-balanced diet, exercising regularly and maintaining a healthy weight — can help protect your heart and arteries.
These behaviors can also reduce your risk of developing health issues that can lead to coronary artery disease, including:
Since cardiac arrest can occur in people who don't have coronary artery disease, you may be wondering whether cardiac arrest is a condition that can be screened for. (Related: 5 Commonly Ordered Heart Tests & What They Show)
"We have ways to screen for the severe arrhythmias that can lead to cardiac arrest, but screening isn't appropriate for everyone," adds Dr. Lisman. "Since we know these issues tend to run in families, there are questions we ask first to help determine a person's risk."
Having a family member with an arrhythmia or who died suddenly before the age of 40 almost always prompts screening. Your doctor will use a test called an electrocardiogram (ECG or EKG) to record the electrical signals of your heart and detect potential issues.
"EKGs catch around 80% of people prone to arrhythmia," says Dr. Lisman.
When to seek emergency care
Both cardiac arrest and heart attack are life-threatening medical emergencies. If you or someone around you is experiencing sudden cardiac arrest or heart attack symptoms, don't ignore them. Calling 911 is the fastest way to get treatment. Time is critical to preserving heart muscle — minutes can be the difference. (Related: Why Timing Matters for Heart Attack Symptoms)
Despite what we know about preventing cardiac arrests, they still happen. It's why Dr. Lisman reminds us of the importance of taking a course to learn how to perform CPR.
"For instance, if your neighbor collapses while mowing the lawn and goes unconscious, being able to provide basic life support until medical professionals arrive can absolutely be life-saving," Dr. Lisman reiterates.
