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What Is a Heart Attack?

A heart attack happens when the flow of oxygen-rich blood to a section of heart muscle suddenly becomes blocked and the heart can't get oxygen. If blood flow isn't restored quickly, the section of heart muscle begins to die.

Heart attacks are a leading killer of both men and women in the United States. The good news is that excellent treatments are available for heart attacks. These treatments can save lives and prevent disabilities.

Heart attack treatment works best when it's given right after symptoms occur. If you think you or someone else is having a heart attack (even if you're not fully sure), call 9–1–1 right away.

Overview

Heart attacks most often occur as a result of coronary heart disease (CHD), also called coronary artery disease. CHD is a condition in which a waxy substance called plaque (plak) builds up inside the coronary arteries. These arteries supply oxygen-rich blood to your heart.

When plaque builds up in the arteries, the condition is called atherosclerosis (ath-er-o-skler-O-sis). The buildup of plaque occurs over many years.

Eventually, an area of plaque can rupture (break open) inside of an artery. This causes a blood clot to form on the plaque's surface. If the clot becomes large enough, it can mostly or completely block blood flow through a coronary artery.

If the blockage isn't treated quickly, the portion of heart muscle fed by the artery begins to die. Healthy heart tissue is replaced with scar tissue. This heart damage may not be obvious, or it may cause severe or long-lasting problems.

Heart With Muscle Damage and a Blocked Artery

Figure A shows a heart with dead heart muscle caused by a heart attack. Figure B is a cross-section of a coronary artery with plaque buildup and a blood clot.  

Figure A shows a heart with dead heart muscle caused by a heart attack. Figure B is a cross-section of a coronary artery with plaque buildup and a blood clot.

A less common cause of heart attack is a severe spasm (tightening) of a coronary artery. The spasm cuts off blood flow through the artery. Spasms can occur in coronary arteries that aren't affected by atherosclerosis.

Heart attacks can be associated with or lead to severe health problems, such as heart failure and life-threatening arrhythmias (ah-RITH-me-ahs).

Heart failure is a condition in which the heart can't pump enough blood to meet the body's needs. Arrhythmias are irregular heartbeats. Ventricular fibrillation is a life-threatening arrhythmia that can cause death if not treated right away.

Don't Wait—Get Help Quickly

Acting fast at the first sign of heart attack symptoms can save your life and limit damage to your heart. Treatment works best when it's given right after symptoms occur.

Many people aren't sure what's wrong when they are having symptoms of a heart attack. Some of the most common warning symptoms of a heart attack for both men and women are:

  • Chest pain or discomfort. Most heart attacks involve discomfort in the center or left side of the chest. The discomfort usually lasts more than a few minutes or goes away and comes back. It can feel like pressure, squeezing, fullness, or pain. It also can feel like heartburn or indigestion.
  • Upper body discomfort. You may feel pain or discomfort in one or both arms, the back, shoulders, neck, jaw, or upper part of the stomach (above the belly button).
  • Shortness of breath. This may be your only symptom, or it may occur before or along with chest pain or discomfort. It can occur when you are resting or doing a little bit of physical activity.

Other possible symptoms of a heart attack include:

  • Breaking out in a cold sweat
  • Feeling unusually tired for no reason, sometimes for days (especially if you are a woman)
  • Nausea (feeling sick to the stomach) and vomiting
  • Light-headedness or sudden dizziness
  • Any sudden, new symptom or a change in the pattern of symptoms you already have (for example, if your symptoms become stronger or last longer than usual)

Not all heart attacks begin with the sudden, crushing chest pain that often is shown on TV or in the movies, or other common symptoms such as chest discomfort. The symptoms of a heart attack can vary from person to person. Some people can have few symptoms and are surprised to learn they've had a heart attack. If you've already had a heart attack, your symptoms may not be the same for another one. 

Quick Action Can Save Your Life: Call 9–1–1

If you think you or someone else may be having heart attack symptoms or a heart attack, don't ignore it or feel embarrassed to call for help. Call 9–1–1 for emergency medical care. Acting fast can save your life.

Do not drive to the hospital or let someone else drive you. Call an ambulance so that medical personnel can begin life-saving treatment on the way to the emergency room. Take a nitroglycerin pill if your doctor has prescribed this type of treatment.

Outlook

Each year, close to 1 million people in the United States have heart attacks, and many of them die. CHD, which often results in heart attacks, is the leading killer of both men and women in the United States.

Many more people could survive or recover better from heart attacks if they got help faster. Of the people who die from heart attacks, about half die within an hour of the first symptoms and before they reach the hospital.

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What is a heart attack?


Heart Attack Clinical Trials

Clinical trials are research studies that explore whether a medical strategy, treatment, or device is safe and effective for humans. To find clinical trials that are currently underway for Heart Attack, visit www.clinicaltrials.gov.


Heart Attack in the News

October 24, 2013
NIH and CDC launch registry for sudden death in the young
A registry of deaths in young people from conditions such as heart disease and epilepsy is being created to help researchers define the scope of the problem and set future research priorities. The National Institutes of Health and the Centers for Disease Control and Prevention are collaborating to create the Sudden Death in the Young Registry.

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Know the Facts and Act Fast!

Collage image of new heart attack materials

When a heart attack happens, any delays in treatment can be deadly. 

Knowing the warning symptoms of a heart attack and how to take action can save your life or someone else’s.

The NHLBI has created a new series of informative, easy-to-read heart attack materials to help the public better understand the facts about heart attacks and how to act fast to save a life.

Click the links to download or order the NHLBI's new heart attack materials:

“Don’t Take a Chance With a Heart Attack: Know the Facts and Act Fast” (also available in Spanish)

“Heart Attack: Know the Symptoms. Take Action.”

“Learn What a Heart Attack Feels Like—It Could Save Your Life”

 
December 17, 2013 Last Updated Icon

The NHLBI updates Health Topics articles on a biennial cycle based on a thorough review of research findings and new literature. The articles also are updated as needed if important new research is published. The date on each Health Topics article reflects when the content was originally posted or last revised.

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