Cardiac arrest vs heart attack: What is the difference?

He had a heart attack? Or may be a cardiac arrest? Aren’t those the same thing?

Actually, no. Not even close.

Though often confused and occasionally occurring together a cardiac arrest and a heart attack are two very different medical emergencies, each requiring different responses, treatments, and outcomes. Understanding the difference could one day save a life maybe even yours.

What is a heart attack?
A heart attack, or myocardial infarction, happens when blood flow to part of the heart is blocked. This blockage — usually caused by a clot in one of the coronary arteries — means the heart muscle isn't getting the oxygen it needs. If not treated quickly, parts of the heart muscle can die.

What is cardiac arrest?
Cardiac arrest is when the heart suddenly stops beating altogether. There’s no pumping. No blood flow. No oxygen to the brain or body. Within seconds, the person loses consciousness. If the heart isn’t restarted, death follows quickly.

"While a heart attack is a plumbing problem, a cardiac arrest is an electrical problem. Cardiac arrest happens when the heart's electrical system malfunctions, causing it to beat rapidly and chaotically — or to stop beating altogether. Without blood circulating to the brain, lungs, and other organs, the person gasps or stops breathing and becomes unresponsive within seconds," explains a Harvard report. A heart attack is a common cause of cardiac arrest, but most heart attacks do not lead to cardiac arrest.

Causes of a heart attack:
Coronary artery disease (CAD) is the main culprit. Plaque builds up in the arteries, narrowing them over time.
A sudden blood clot can completely block an artery already narrowed by plaque.
Spasms in a coronary artery can also restrict blood flow, though this is less common.

Risk factors include:

• High cholesterol
• Smoking
• Diabetes
• High blood pressure
• Stress
• Poor diet and lack of exercise

Causes of cardiac arrest
The most common trigger? An abnormal heart rhythm, especially a deadly one called ventricular fibrillation (VFib). In VFib, the heart’s electrical signals fire chaotically, stopping effective pumping.

Cardiac arrest can also be caused by:

• Heart attacks (yes, one can cause the other)
• Severe arrhythmias (irregular heartbeats)
• Heart failure
• Trauma (like electrocution or blunt force)
• Drug overdose
• Drowning
• Genetic conditions like Long QT Syndrome

Heart attack symptoms
Often gradual, sometimes subtle, and commonly misread — especially by women.

• Chest pain or pressure (may feel like squeezing, fullness, or pain)
• Pain radiating to the left arm, jaw, neck, or back
• Shortness of breath
• Cold sweat
• Nausea or vomiting
• Lightheadedness
• Fatigue

Note: Some people, especially diabetics and women, may have what’s called a “silent” heart attack — with symptoms so mild or strange they’re missed altogether.

Cardiac arrest symptoms
It’s often sudden and shocking.

• Sudden collapse
• No pulse
• No breathing
• Loss of consciousness
• Before collapse: some may experience chest discomfort, dizziness, or racing heartbeat

What’s the emergency response?
If someone is having a heart attack:
Call emergency services immediately.

Keep them calm.
Loosen tight clothing.
If the person isn’t allergic, a 325mg aspirin can help thin the blood.

Key: The faster blood flow is restored, the more of the heart muscle can be saved. Time is muscle.

If someone goes into cardiac arrest:
Call emergency services immediately. Start CPR (chest compressions only if you’re not trained in mouth-to-mouth). Use an AED (automated external defibrillator) if available.

These devices are made for the public — they walk you through the process with voice instructions. Continue CPR until help arrives or the person regains consciousness.

Key: Every second matters. Brain cells start dying within minutes without oxygen.

Why this matters
Misunderstanding the difference between a heart attack and cardiac arrest can delay the right kind of help. And when it comes to your heart — every minute counts.

Heart attacks are serious. Cardiac arrest is deadly unless treated immediately. Knowing which is which could mean the difference between panic and action.

So, next time you hear someone mixing them up, gently correct them. Or better yet, sign up for a CPR course. Because someday, you might be the one standing there when someone’s heart needs a reboot.

Disclaimer: This article is for informational purposes only. Always seek professional medical attention if you or someone around you experiences chest pain, unconsciousness, or any heart-related symptoms.