Sudden cardiac arrest (SCA) isn’t the same as a heart attack, though people often use the terms interchangeably. While both are life-threatening heart conditions, understanding the differences could be lifesaving. Cardiologist Nicholas Ruthmann, MD, clears up the confusion in this Q&A.
Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy
Q. How does sudden cardiac arrest differ from a heart attack?
A. Think of your house: It needs plumbing and electricity to work as it should — and it has the potential for both plumbing and electrical problems. The same can happen with your heart.
Heart attacks are primarily a plumbing (blood flow) problem; SCA is an electrical (heart rhythm) problem. But heart attacks can create problems that lead to sudden cardiac arrest.
Q: What’s a heart attack, and why is it a plumbing problem?
A. Your coronary arteries are the pipes that supply blood to the heart. Sometimes, heart arteries get clogged by fatty deposits called plaques (a condition called atherosclerosis). When that happens, it’s harder for the blood to flow around the plaque.
Think of a slow-draining sink — when the pipe gets clogged with hair or debris, water doesn’t flow freely. And this problem can be life-threatening when it’s your heart: If not enough oxygenated blood reaches the heart muscle, the muscle tissue begins to die — a heart attack.
Q: So how is sudden cardiac arrest an electrical problem?
A. The heart has a built-in electrical conduction system that keeps it beating at a steady pace. Underlying conditions, such as high blood pressure, high cholesterol or previous heart attacks, can result in problems with that electrical system. The malfunction could lead to a dangerously fast and erratic heart rhythm (arrhythmia). As a result, the heart stops beating effectively — it quivers or appears “stunned,” and it can no longer pump blood to the brain and other organs.
Cardiac arrest often affects older people. But young people with genetic heart problems are also at risk. If you have a heart condition, talk to your doctor about preventive care.
Q. What are the symptoms of a heart attack?
A. People experiencing a heart attack often stay conscious and awake. In an acute heart attack, there’s usually one major blockage that some blood can flow around. The circulation is not as strong, but blood still reaches vital organs and the brain, so the person stays awake. If you have a heart attack, you might experience these symptoms over hours, days or weeks:
- Chest pain.
- Nausea or flu-like symptoms.
- Shortness of breath.
- Stomach pain.
- Sweating.
- Weakness.
Q. How do the symptoms differ for sudden cardiac arrest?
A. People having sudden cardiac arrest often lose consciousness within minutes because of the lack of blood flow to the brain. There is little-to-no warning. More than half of people who experience SCA have no symptoms. Others may have:
- Blue discoloration of the face.
- Breathing difficulty.
- Chest pains.
- Dizziness as the heart quivers.
- Overall malaise or unwell feelings.
Q. Why is it important for people to know the difference between a heart attack and sudden cardiac arrest?
A. We often say, “time is tissue.” This means the longer you wait to get help, the more damage can occur to the heart tissue. So, if you or your loved one has symptoms, knowing the difference can help you make lifesaving decisions.
For example:
- Sudden loss of consciousness: Call 911, look for an automated external defibrillator (AED) and begin CPR immediately.
- Conscious with symptoms: Call 911 or go to the nearest emergency room.
Also, if you’ve experienced a previous heart attack or have heart disease, you’re at higher risk for SCA. The risk of SCA following a heart attack is highest in the first three months, then gradually decreases. Your doctor can help you figure out what preventive steps to take.
Q. Does sudden cardiac arrest always lead to death?
A. If SCA occurs outside the hospital, the survival rate is around 10%. However, that rate jumps to 90% when the person receives the following within minutes of collapsing:
- CPR, to circulate blood and oxygen.
- Shock therapy from an AED, to reset the heart’s electrical system.
Q. What are some ways to help prevent heart attack and sudden cardiac arrest?
A. Heart-healthy habits are an essential first step. Controlling risk factors helps prevent heart attacks or SCA — so talk to your doctor about how to lower your blood pressure, quit smoking, control diabetes, stay active and eat a heart-healthy diet.
If you have a heart condition or had a previous heart attack, your provider will discuss preventive care options. These may include:
- Medication: Your provider may recommend drugs to lower cholesterol, prevent future heart attacks, lower blood pressure or prevent blood clots.
- Ablation: Heart attacks can lead to heart muscle damage which can harm the electrical conduction system. Ablation – burning or freezing of the heart tissue – can correct abnormal electrical pathways.
- Defibrillators: External or internal devices can detect when the heart is beating out of sync and shock it back into proper function. Researchers are currently developing portable AEDs that at-risk people can carry with them.
- Procedures: If you have a genetic condition that puts you at a higher risk for electrical heart concerns, a surgical procedure may correct the condition.
- Stents: Scaffold-like devices can open up blocked coronary arteries and improve blood flow, preventing future heart attacks that could lead to SCA.
The most important step in preventing a heart attack or SCA is this: If you feel something, say something. This advice is particularly important during the pandemic when people might be concerned about visiting the emergency department. If you are experiencing symptoms, it’s crucial to talk with your doctor. Most providers now offer telemedicine visits to help determine if you need immediate care.
