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What’s the difference between a heart attack, heart failure, and stroke?

Heart attack, heart failure and stroke are different conditions that affect people in different ways. Dr. Paula Harvey, director of the cardiovascular research program at Women’s College Hospital, explains the difference.

Heart attack

A heart attack happens when the heart is not getting enough oxygenated blood, usually because one of the major blood vessels that supply the heart has become blocked.

The most common cause of heart attacks is the accumulation of plaque in an artery.

“Plaque is the buildup of cholesterol and inflammatory material in the lining of the artery,” Dr. Harvey says. “If that ruptures, it causes the blood to form a clot. That blood clot can then completely block off the artery, so you’re not getting any oxygenated blood past that blockage to the heart. If it’s not opened with clot-busting techniques, then that part of the heart muscle will die.”

Preventing plaque buildup in the arteries can prevent the formation of blood clots that cause heart attacks.

In heart attack survivors, the affected part of the heart is scarred, and can no longer help the heart pump blood. This is one of the causes of heart failure.

A heart attack is a medical emergency, and can be fatal.

Heart failure

Heart failure means that the heart is not pumping effectively, either because the heart is damaged and unable to contract properly, or because the heart has become too stiff.

In order to pump blood effectively, the heart must be able to contract to push blood out, and then relax to fill up with more blood. Damage to the heart muscle can make it unable to contract properly. If the heart becomes too stiff, it is unable to relax. That makes it unable to draw in enough blood from the lungs to fill properly.

“So a heart attack can lead to heart failure because it can damage the muscle. There are many other causes of heart failure due to pump failure, but damage from heart attacks is one of the most common,” Dr. Harvey says.

“We know heart failure can occur when the heart muscle is just too stiff as well. And that occurs with things like high blood pressure, diabetes, obesity or increasing age.”

In addition to an inability to pump enough oxygenated blood to the body, heart failure can also cause back pressure into the lungs, pushing fluid into the lungs.

“When people get fluid in the lungs they get short of breath, they swelling in the legs, and they get very fatigued,” Dr. Harvey says. “These are often symptoms of heart failure.”

In most cases, heart failure is a progressive chronic condition.


A stroke happens when part of the brain does not get enough oxygenated blood.

Although stroke happens in the brain, it is sometimes confused with heart attack, possibly because both are related to blood flow.

“Stroke is caused by problems with blood flow to the brain, as opposed to a heart attack which is obviously blood flow to the heart,” Dr. Harvey explains.

A stroke can be caused by a blocked blood vessel (called ischemic stroke, the most common type) or by a ruptured blood vessel causing bleeding in the brain (hemorrhagic stroke).

Like heart attack, ischemic stroke is often caused by plaque buildup or a dislodged blood clot causing a blockage. The disruption of blood flow to the brain during a stroke can damage that part of the brain. It is vital to re-establish blood flow as soon as possible to minimize damage.

A stroke is a medical emergency.

This information is provided by Women’s College Hospital and is not intended to replace the medical advice of your doctor or health care provider. Please consult your health care provider for advice about a specific medical condition. This document was last reviewed on: June 20, 2016

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