Is cardiac arrest the same thing as a heart attack

Heart attack or cardiac arrest: Aren't they the same thing?

People often think that a cardiac arrest and a heart attack mean the same thing, but they are different.

Putting it simply, your heart is a pump which is made up of two systems - a plumbing system and an electrical system.

What is a heart attack?

The heart has coronary arteries which supply the heart muscle with the blood and nutrients it needs.

A heart attack is when one of the coronary arteries becomes completely blocked with plaque and blood clot – much like a blocked pipe. This blockage stops the flow of blood to the heart i.e.a plumbing problem.

This image below shows what happens during a heart attack.

Some people have a higher chance of having a heart attack than others. This can be due to their family history (genes) or age.

There are also certain lifestyle factors that increase your risk of a heart attack such as having high cholesterol, high blood pressure, diabetes, depression, or being physically inactive, overweight or a smoker.

The treatment for a heart attack requires opening the blocked artery with a stent or by creating a bypass around the blockage, known as cardiac bypass surgery. 

A person experiencing a heart attack usually remains conscious (awake) and experiences symptoms such as pressure in their chest or shortness of breath.

You can learn more about heart attacks here.

What is a cardiac arrest?

The heart has its own electrical system which triggers the heart to beat in rhythm and pump blood around the body. 

This diagram below shows the heart's electrical pathway.

In a cardiac arrest the hearts electrical system “short circuits”, causing abnormal heart rhythms (called arrhythmias) and the heart to stop pumping.

When this happens, the person has no pulse and quickly loses consciousness.

The treatment for a cardiac arrest, or electrical fault, is defibrillation or a “shock.”

What is the link between a heart attack and a cardiac arrest?

A blockage in the coronary arteries means the heart’s cells are starved of oxygen, which may lead to abnormal heart rhythms.

Therefore, a heart attack can progress to a cardiac arrest, though usually doesn't if promptly treated.

The table below outlines the differences between a heart attack and a cardiac arrest.

What to do

Both situations are medical emergencies and require immediate medical attention. Call 000 (if calling within Australia). 

The sooner the condition is treated, the better the outcome. 

Ask the doctor

Q. My grandfather had a heart attack in his mid-70s, but he survived and lived until age 93. My father also had heart disease, but he died of cardiac arrest when he was just 67. What’s the difference between a heart attack and cardiac arrest?

A. These two terms often confuse people because they’re sometimes used interchangeably. But a heart attack and cardiac arrest are not the same thing.

A heart attack is a circulation problem that happens when a blocked artery prevents blood flow to part of the heart muscle. If the artery isn’t reopened to restore blood flow, the heart cells supplied by that artery start to die. Symptoms include intense discomfort in the center of the chest or other parts of the upper body, breathlessness, sweating, and nausea. But the heart continues to beat, and the person remains awake.

In contrast, cardiac arrest is most often an electrical problem that causes the heart to abruptly and unexpectedly stop beating. An electrical misfire causes the heart’s lower chambers (ventricles) to flutter or quiver, known as ventricular fibrillation (v-fib). During cardiac arrest, a person suddenly collapses or faints, stops breathing normally, and can’t be roused. Other symptoms can include irregular, odd gasping or choking sounds (known as agonal breathing) and twitching muscles.

Most heart attacks do not trigger cardiac arrest. However, when cardiac arrest does occur, a heart attack is often to blame. Sometimes, the oxygen-starved heart muscle triggers v-fib during a heart attack. Scar tissue from a heart attack can also damage the heart, leaving it unable to pump effectively. A weakened heart is more prone to v-fib.

Because cardiac arrest is so closely tied to coronary artery disease (the root cause of heart attacks), the underlying risks are largely the same. These include smoking, diabetes, high cholesterol, physical inactivity, obesity, high blood pressure, and a family history of early heart disease.

Other heart conditions that can predispose people to cardiac arrest include weak heart muscle (cardiomyopathy), heart valve problems, and inherited conditions that affect the heart’s electrical system, such as long QT syndrome. Some drug use increases risk as well, particularly using drugs such as cocaine or amphetamines or overdosing on opioids or other pain medications.

Finally, the risk of cardiac arrest rises slightly during and for up to 30 minutes after strenuous exercise, especially in people who are out of shape. But the odds are estimated at one in 1.5 million during any one exercise episode, which is far outweighed by the overall heart-protecting benefits of exercise.

— Deepak L. Bhatt, M.D., M.P.H.
Editor in Chief, Harvard Heart Letter

Image: © Moyo Studio/Getty Images

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