Cardiac Arrest: What You Need to Know

As witnessed in the tragic death of rock legend Tom Petty, who was only 66, sudden cardiac arrest is a perilous business. Here’s an overview of sudden cardiac arrest, and how it differs from heart attack—and stroke.

The first thing to note is that while the terms “heart attack” and “cardiac arrest” are often used interchangeably, they’re actually two distinct conditions. The main difference: a heart attack is a circulation problem—meaning blood flow to the heart is physically blocked by a narrowed or clogged artery—while in the case of a cardiac arrest there is no obstruction to blood flow. Instead an electrical malfunction causes the heart to stop beating altogether, which means blood isn’t flowing anywhere in the body. It’s vital to know the difference between the two.

See the video below for more on how to tell the two apart, and what to do if someone near you is having a heart attack or going into cardiac arrest.


Read on for an overview of what causes sudden cardiac arrest, and how it differs from heart attack and stroke.

Sudden Cardiac Arrest

What is it? Cardiac arrest is not a synonym for a ‘massive heart attack’, but is the sudden, unexpected loss of heart function, breathing and consciousness (unlike a heart attack where despite a blockage of blood flow to portions of the heart, it is still functioning). Cardiac arrest usually results from an electrical disturbance in the heart. This electrical malfunction disrupts the heart’s pumping action, causing blood to stop flowing to the rest of the body.

Sudden cardiac arrest is more likely to develop in a person with a pre-existing heart condition such as coronary artery disease or congenital heart disease.

If not treated immediately, cardiac arrest is fatal. Brain death starts to occur in only 4 to 6 minutes after someone has a cardiac arrest. It can be reversed, however, if it’s treated within a few minutes with an electric shock (or defibrillation) to the heart to restore a normal heartbeat. A victim’s chances of survival are reduced by 7 to 10 percent with every minute that passes without cardiopulmonary resuscitation (CPR) and defibrillation. And few attempts at resuscitation succeed after 10 minutes.

It’s estimated that more than 95 percent of cardiac arrest victims die before reaching the hospital, according to the American Heart Association. But in situations where defibrillation is provided within 5 to 7 minutes, the survival rate is as high as 30–45 percent.

What are the symptoms? The signs of sudden cardiac arrest are sudden and drastic. They include:

— Sudden collapse

— No pulse

— No breathing

— Loss of consciousness

Other less severe symptoms that can sometimes precede cardiac arrest include fatigue, fainting, blackouts, dizziness, chest pain, shortness of breath, palpitations or vomiting. But sudden cardiac arrest often occurs with little or no warning.

If someone experiences sudden cardiac arrest, it is vital to take urgent action. According to the Mayo Clinic, after alerting 911, you should take these steps:

— If the person isn’t breathing normally, begin CPR. If you don’t know CPR, push hard and fast on the person’s chest — about two compressions per second or 100 per minute. Allow the chest to rise completely between compressions. Don’t worry about breathing into the person’s mouth. Keep doing this until a portable defibrillator is available or emergency personnel arrive.

— Use a portable defibrillator, if one is available. If you’re not trained to use a portable defibrillator, a 911 or emergency medical help operator may be able to guide you. Note: Portable automatic external defibrillators (AEDs) are available in an increasing number of places, including airports, health clubs, casinos and shopping malls. You can also purchase them for your home. AEDs come with built-in instructions for their use, and are programmed to allow a shock only when appropriate.

NEXT: Heart Attack

Heart Attack

What is it? Unlike sudden cardiac arrest — where the heart stops beating and requires a shock to get restarted — a heart attack is usually less an electrical defect than a serious blockage, or if you will, a plumbing issue. A heart attack occurs when a blood clot blocks the flow of blood through a coronary artery that supplies blood to the heart. This interrupted blood flow can damage or destroy a part of the heart muscle.

Years ago, a heart attack was often fatal, but improved treatments and better awareness of symptoms mean that most people who now have a heart attack survive. Lifestyle choices such as following a healthy diet and exercise program, as well as taking steps to reduce stress can both help to prevent a heart attack and facilitate recovery from one.

What are the symptoms? Common signs of a heart attack include:

–Pressure, fullness or a squeezing pain in the center of your chest that lasts for more than a few minutes

— Pain extending beyond your chest to your shoulder, arm, back, or even to your teeth and jaw

— Increasing episodes of chest pain

— Prolonged pain in the upper abdomen

— Shortness of breath

— Sweating

— Impending sense of doom

— Fainting

— Nausea and vomiting

Symptoms for women may be different — and in some cases, more subtle — than those for men. Women should also be on the look out for:

— Abdominal pain or “heartburn”

— Clammy skin

— Lightheadedness or dizziness

— Unusual or unexplained fatigue

(For more see Women and heart disease.)

Some heart attacks strike suddenly, but many people experience warning signs and symptoms hours, days or even weeks in advance. The earliest predictor of an attack may be recurrent chest pain (angina) that’s triggered by exertion and relieved by rest. (See All about angina.)

It’s important to remember that not all people who have heart attacks experience them to the same degree, and many heart attacks aren’t as dramatic as the ones you may have seen on TV. In fact, some people have no symptoms at all. As with other serious conditions, get medical attention immediately. While relatively uncommon, a heart attack could lead to cardiac arrest if you don’t get help soon enough.



What is it? A stroke occurs when the blood supply to a part of your brain is interrupted or severely reduced, depriving brain tissue of oxygen and nutrients. Within a few minutes, brain cells begin to die.

What are the symptoms? Watch for these warning signs if you think you or someone else is having a stroke:

— Difficulty walking. If you’re having a stroke, you may stumble or have sudden dizziness, loss of balance or loss of coordination.

— Difficulty talking. You may slur your speech or may not be able to come up with words to explain what is happening (aphasia). As a test, try to repeat a simple sentence. If you can’t, you may be having a stroke.

— Paralysis or numbness on one side of the body. Try to raise both your arms over your head at the same time. If one arm begins to fall, you may be having a stroke.

— Vision problems. If you’re having a stroke, you may suddenly have blurred or blackened vision or may see double.

— Headache. A sudden, severe “out of the blue” headache, which may be accompanied by a stiff neck, facial pain, pain between the eyes, vomiting or altered consciousness, sometimes indicates a stroke.

As with cardiac arrest and heart attack, a stroke is a medical emergency, and prompt treatment is crucial. Early treatment can minimize damage to your brain as well as any potential complications. Fewer people now die of strokes than was the case 20 or 30 years ago. Better control of the major risk factors for stroke — high blood pressure, smoking and high cholesterol — is likely responsible for the decline.


— Risk factors include a family history of coronary artery disease, smoking, high blood pressure, high blood cholesterol, obesity, diabetes, and a sedentary lifestyle. Other factors that may increase risk include a previous episode of cardiac arrest or a previous heart attack.

— The incidence of sudden cardiac arrest increases with age, especially after age 45 for men and age 55 for women.

— Men are two to three times more likely than women to experience sudden cardiac arrest.

— Other factors that can trigger sudden cardiac arrest include using drugs, such as cocaine or amphetamines, a lightning strike or another electrical shock, or immersion in cold water.

Sources: The Mayo Clinic, The Canadian Institutes of Health Research (CIHR), American Heart Association, Heart and Stroke Foundation of Canada.