For more information, visit http://www.nhlbi.nih.gov/health/health-topics/topics/heartattack/

Other Names for a Heart Attack

• Myocardial infarction (MI)
• Acute myocardial infarction (AMI)
• Acute coronary syndrome
• Coronary thrombosis
• Coronary occlusion

What Causes a Heart Attack?

Coronary Heart Disease

A heart attack happens if the flow of oxygen-rich blood to a section of heart muscle suddenly becomes blocked. Most heart attacks occur as a result of coronary heart disease (CHD).

CHD is a condition in which a waxy substance called plaque builds up inside of the coronary arteries. These arteries supply oxygen-rich blood to your heart.

When plaque builds up in the arteries, the condition is called atherosclerosis. 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.

Coronary Artery Spasm

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.

What causes a coronary artery to spasm isn't always clear. A spasm may be related to:

• Taking certain drugs, such as cocaine
• Emotional stress or pain
• Exposure to extreme cold
• Cigarette smoking

The animation below shows how plaque buildup or a coronary artery spasm can lead to a heart attack. Click the "start" button to play the animation. Written and spoken explanations are provided with each frame. Use the buttons in the lower right corner to pause, restart, or replay the animation, or use the scroll bar below the buttons to move through the frames.

The animation shows how blocked blood flow in a coronary artery can lead to a heart attack.

Who Is at Risk for a Heart Attack?

Certain risk factors make it more likely that you'll develop coronary heart disease (CHD) and have a heart attack. You can control many of these risk factors.

Risk Factors You Can Control

The major risk factors for a heart attack that you can control include:

• Smoking
• High blood pressure
• High blood cholesterol
• Overweight and obesity
• An unhealthy diet (for example, a diet high in saturated fat, trans fat, cholesterol, and sodium)
• Lack of routine physical activity
• High blood sugar due to insulin resistance or diabetes  

Some of these risk factors—such as obesity, high blood pressure, and high blood sugar—tend to occur together. When they do, it's called metabolic syndrome.

In general, a person who has metabolic syndrome is twice as likely to develop heart disease and five times as likely to develop diabetes as someone who doesn't have metabolic syndrome.

For more information about the risk factors that are part of metabolic syndrome, go to the Health Topics Metabolic Syndrome article.

Risk Factors You Can't Control

Risk factors that you can't control include:

• Age. The risk of heart disease increases for men after age 45 and for women after age 55 (or after menopause).
• Family history of early heart disease. Your risk increases if your father or a brother was diagnosed with heart disease before 55 years of age, or if your mother or a sister was diagnosed with heart disease before 65 years of age.
• Preeclampsia (pre-e-KLAMP-se-ah). This condition can develop during pregnancy. The two main signs of preeclampsia are a rise in blood pressure and excess protein in the urine. Preeclampsia is linked to an increased lifetime risk of heart disease, including CHD, heart attack, heart failure, and high blood pressure.

What Are the Signs and Symptoms of a Heart Attack?

Not all heart attacks begin with the sudden, crushing chest pain that often is shown on TV or in the movies. In one study, for example, one-third of the patients who had heart attacks had no chest pain. These patients were more likely to be older, female, or diabetic.

The warning signs and symptoms of a heart attack aren't the same for everyone. Many heart attacks start slowly as mild pain or discomfort. Some people don't have symptoms at all. Heart attacks that occur without any symptoms or very mild symptoms are called silent heart attacks.

Chest Pain or Discomfort

The most common heart attack symptom is chest pain or discomfort. This includes new chest pain or discomfort or a change in the pattern of existing chest pain or discomfort.

Most heart attacks involve discomfort in the center or left side of the chest that often lasts for more than a few minutes or goes away and comes back. The discomfort can feel like uncomfortable pressure, squeezing, fullness, or pain. The feeling can be mild or severe.

Heart attack pain sometimes feels like indigestion or heartburn.

The symptoms of angina (an-JI-nuh or AN-juh-nuh) can be similar to the symptoms of a heart attack. Angina is chest pain that occurs in people who have coronary heart disease, usually when they're active. Angina pain usually lasts for only a few minutes and goes away with rest.

Chest pain or discomfort that doesn't go away or changes from its usual pattern (for example, occurs more often or while you're resting) can be a sign of a heart attack.

All chest pain should be checked by a doctor.

Other Common Signs and Symptoms

Other common signs and symptoms of a heart attack include new onset of:

• Upper body discomfort in one or both arms, the back, neck, jaw, or upper part of the stomach
• Shortness of breath, which may occur with or before chest discomfort
• Nausea (feeling sick to your stomach), vomiting, light-headedness or sudden dizziness, or breaking out in a cold sweat
• Sleep problems, fatigue (tiredness), or lack of energy

Not everyone having a heart attack has typical symptoms. If you've already had a heart attack, your symptoms may not be the same for another one. However, some people may have a pattern of symptoms that recur.

The more signs and symptoms you have, the more likely it is that you're having a heart attack.

Act Fast

The signs and symptoms of a heart attack can develop suddenly. However, they also can develop slowly—sometimes within hours, days, or weeks of a heart attack.

Know the warning signs of a heart attack so you can act fast to get treatment for yourself or someone else. The sooner you get emergency help, the less damage your heart will sustain.

Call 9–1–1 for help right away if you think you or someone else may be having a heart attack. You also should call for help if your chest pain doesn't go away as it usually does when you take medicine prescribed for angina.

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.

How Is a Heart Attack Diagnosed?

Your doctor will diagnose a heart attack based on your signs and symptoms, your medical and family histories, and test results.

Diagnostic Tests

EKG (Electrocardiogram)

An EKG is a simple, painless test that detects and records the heart's electrical activity. The test shows how fast the heart is beating and its rhythm (steady or irregular). An EKG also records the strength and timing of electrical signals as they pass through each part of the heart.

An EKG can show signs of heart damage due to coronary heart disease (CHD) and signs of a previous or current heart attack.

Blood Tests

During a heart attack, heart muscle cells die and release proteins into the bloodstream. Blood tests can measure the amount of these proteins in the bloodstream. Higher than normal levels of these proteins suggest a heart attack.

Commonly used blood tests include troponin tests, CK or CK–MB tests, and serum myoglobin tests. Blood tests often are repeated to check for changes over time.

Coronary Angiography

Coronary angiography (an-jee-OG-ra-fee) is a test that uses dye and special x rays to show the insides of your coronary arteries. This test often is done during a heart attack to help find blockages in the coronary arteries.

To get the dye into your coronary arteries, your doctor will use a procedure called cardiac catheterization (KATH-e-ter-ih-ZA-shun).

A thin, flexible tube called a catheter is put into a blood vessel in your arm, groin (upper thigh), or neck. The tube is threaded into your coronary arteries, and the dye is released into your bloodstream.

Special x rays are taken while the dye is flowing through the coronary arteries. The dye lets your doctor study the flow of blood through the heart and blood vessels.

If your doctor finds a blockage, he or she may recommend a procedure called angioplasty (AN-jee-oh-plas-tee). This procedure can help restore blood flow through a blocked artery. Sometimes a small mesh tube called a stent is placed in the artery to help prevent blockages after the procedure.

How Is a Heart Attack Treated?

Early treatment for a heart attack can prevent or limit damage to the heart muscle. Acting fast, at the first symptoms of a heart attack, can save your life. Medical personnel can begin diagnosis and treatment even before you get to the hospital.

Certain treatments usually are started right away if a heart attack is suspected, even before the diagnosis is confirmed. These include:

• Oxygen therapy
• Aspirin to thin your blood and prevent further blood clotting
• Nitroglycerin to reduce your heart's workload and improve blood flow through the coronary arteries
• Treatment for chest pain

Once the diagnosis of a heart attack is confirmed or strongly suspected, doctors start treatments to try to promptly restore blood flow to the heart. The two main treatments are "clot-busting" medicines and angioplasty, a procedure used to open blocked coronary arteries.

Clot-Busting Medicines

Thrombolytic medicines, also called "clot busters," are used to dissolve blood clots that are blocking the coronary arteries. To work best, these medicines must be given within several hours of the start of heart attack symptoms. Ideally, the medicine should be given as soon as possible.

Angioplasty

Angioplasty is a nonsurgical procedure that opens blocked or narrowed coronary arteries. This procedure also is called percutaneous (per-ku-TA-ne-us) coronary intervention, or PCI.

A thin, flexible tube with a balloon or other device on the end is threaded through a blood vessel to the narrowed or blocked coronary artery.

Once in place, the balloon is inflated to compress the plaque against the wall of the artery. This restores blood flow through the artery.

During the procedure, the doctor may put a small mesh tube called a stent in the artery. The stent helps prevent blockages in the artery in the months or years after angioplasty.

For more information, go to the Health Topics Angioplasty article.

Other Treatments for Heart Attack

Medicines

• Beta blockers. Beta blockers decrease your heart's workload. These medicines also are used to relieve chest pain and discomfort and to help prevent repeat heart attacks. Beta blockers also are used to treat arrhythmias (irregular heartbeats).
• ACE inhibitors. ACE inhibitors lower blood pressure and reduce strain on your heart. They also help slow down further weakening of the heart muscle.
• Anticoagulants. Anticoagulants, or "blood thinners," prevent blood clots from forming in your arteries. These medicines also keep existing clots from getting larger.
• Anticlotting medicines. Anticlotting medicines stop platelets from clumping together and forming unwanted blood clots. Examples of anticlotting medicines include aspirin and clopidogrel.

You also may be given medicines to relieve pain and anxiety, treat arrhythmias (which often occur during a heart attack), or lower your cholesterol (these medicines are called statins).

Medical Procedures

Coronary artery bypass grafting (CABG) also may be used to treat a heart attack. During CABG, a surgeon removes a healthy artery or vein from your body. The artery or vein is then connected, or grafted, to the blocked coronary artery.

The grafted artery or vein bypasses (that is, goes around) the blocked portion of the coronary artery. This provides a new route for blood to flow to the heart muscle.

For more information, go to the Health Topics Coronary Artery Bypass Grafting article.

Treatment After You Leave the Hospital

Most people spend several days in the hospital after a heart attack. When you leave the hospital, treatment doesn't stop. At home, your treatment may include daily medicines and cardiac rehabilitation (rehab). Your doctor may want you to have a flu shot and pneumococcal vaccine each year.

Your doctor also may recommend lifestyle changes, including following a heart healthy diet, being physically active, maintaining a healthy weight, and quitting smoking. Taking these steps can lower your chances of having another heart attack.

Cardiac Rehabilitation

Your doctor may recommend cardiac rehab to help you recover from a heart attack and to help prevent another heart attack. Almost everyone who has had a heart attack can benefit from rehab.

Cardiac rehab is a medically supervised program that may help improve the health and well-being of people who have heart problems.

The cardiac rehab team may include doctors, nurses, exercise specialists, physical and occupational therapists, dietitians or nutritionists, and psychologists or other mental health specialists.

Rehab has two parts:

• Exercise training. This part helps you learn how to exercise safely, strengthen your muscles, and improve your stamina. Your exercise plan will be based on your personal abilities, needs, and interests.
• Education, counseling, and training. This part of rehab helps you understand your heart condition and find ways to reduce your risk of future heart problems. The rehab team will help you learn how to cope with the stress of adjusting to a new lifestyle and deal with your fears about the future.

For more information, go to the Health Topics Cardiac Rehabilitation article.

How Can a Heart Attack Be Prevented?

Lowering your risk factors for coronary heart disease (CHD) can help you prevent a heart attack. (For more information about risk factors, go to "Who Is at Risk for a Heart Attack?")

Even if you already have CHD, you can still take steps to lower your risk for a heart attack. These steps involve following a heart healthy lifestyle and getting ongoing care.

Heart Healthy Lifestyle

Following a healthy diet is an important part of a heart healthy lifestyle. A healthy diet includes a variety of fruits, vegetables, and whole grains. It also includes lean meats, poultry, fish, beans, and fat-free or low-fat milk or milk products. A healthy diet is low in saturated fat, trans fat, cholesterol, sodium (salt), and added sugars.

For more information about following a healthy diet, go to the National Heart, Lung, and Blood Institute's (NHLBI's) Aim for a Healthy Weight Web site, "Your Guide to a Healthy Heart," and "Your Guide to Lowering Your Blood Pressure With DASH." All of these resources provide general information about healthy eating.

If you're overweight or obese, work with your doctor to create a reasonable weight-loss plan that involves diet and physical activity. Controlling your weight helps you control risk factors for CHD and heart attack.

Be as physically active as you can. Physical activity can improve your fitness level and your health. Talk with your doctor about what types of activity are safe for you.

For more information about physical activity, go to the Health Topics Physical Activity and Your Heart article and the NHLBI's "Your Guide to Physical Activity and Your Heart."

If you smoke, quit. Smoking can raise your risk of CHD and heart attack. Talk with your doctor about programs and products that can help you quit. Also, try to avoid secondhand smoke. For more information about quitting smoking, go to the Health Topics Smoking and Your Heart article.

Ongoing Care

Treat Related Conditions

Treating conditions that make a heart attack more likely also can help lower your risk for a heart attack. These conditions may include:

• High blood cholesterol. Your doctor may prescribe medicine to lower your cholesterol if diet and exercise aren't enough.
• High blood pressure. You doctor may prescribe medicine to keep your blood pressure under control.
• Diabetes (high blood sugar). If you have diabetes, try to control your blood sugar level through diet and physical activity (as your doctor recommends). If needed, take medicine as prescribed.

Have an Emergency Action Plan

Make sure that you have an emergency action plan in case you or someone in your family has a heart attack. This is very important if you're at high risk for a heart attack or have already had a heart attack.

Talk with your doctor about the signs and symptoms of a heart attack, when you should call 9–1–1, and steps you can take while waiting for medical help to arrive.

Life After a Heart Attack

Many people survive heart attacks and live active, full lives. If you get help quickly, treatment can limit damage to your heart muscle. Less heart damage improves your chances for a better quality of life after a heart attack.

Medical Followup

After a heart attack, you'll need treatment for coronary heart disease (CHD). This will help prevent another heart attack. Your doctor may recommend:

• Lifestyle changes, such as following a healthy diet, being physically active, maintaining a healthy weight, and quitting smoking
• Medicines to control chest pain or discomfort, high blood cholesterol, high blood pressure, and your heart's workload
• A cardiac rehabilitation program

If you find it hard to get your medicines or take them, talk with your doctor. Don't stop taking medicines that can help you prevent another heart attack.

Returning to Normal Activities

After a heart attack, most people who don't have chest pain or discomfort or other problems can safely return to most of their normal activities within a few weeks. Most can begin walking right away.

Sexual activity also can begin within a few weeks for most patients. Talk with your doctor about a safe schedule for returning to your normal routine.

If allowed by State law, driving usually can begin within a week for most patients who don't have chest pain or discomfort or other problems. Each State has rules about driving a motor vehicle following a serious illness. People who have complications shouldn't drive until their symptoms have been stable for a few weeks.

Anxiety and Depression After a Heart Attack

After a heart attack, many people worry about having another heart attack. Sometimes they feel depressed and have trouble adjusting to new lifestyle changes.

Talk about how you feel with your health care team. Talking to a professional counselor also can help. If you're very depressed, your doctor may recommend medicines or other treatments that can improve your quality of life.

Joining a patient support group may help you adjust to life after a heart attack. You can see how other people who have the same symptoms have coped with them. Talk with your doctor about local support groups or check with an area medical center.

Support from family and friends also can help relieve stress and anxiety. Let your loved ones know how you feel and what they can do to help you.

Risk of a Repeat Heart Attack

Once you've had a heart attack, you're at higher risk for another one. Knowing the difference between angina and a heart attack is important. Angina is chest pain that occurs in people who have CHD.

The pain from angina usually occurs after physical exertion and goes away in a few minutes when you rest or take medicine as directed.

The pain from a heart attack usually is more severe than the pain from angina. Heart attack pain doesn't go away when you rest or take medicine.

If you don't know whether your chest pain is angina or a heart attack, call 9–1–1.

The symptoms of a second heart attack may not be the same as those of a first heart attack. Don't take a chance if you're in doubt. Always call 9–1–1 right away if you or someone else has heart attack symptoms.

Unfortunately, most heart attack victims wait 2 hours or more after their symptoms start before they seek medical help. This delay can result in lasting heart damage or death.

Clinical Trials

The National Heart, Lung, and Blood Institute (NHLBI) is strongly committed to supporting research aimed at preventing and treating heart, lung, and blood diseases and conditions and sleep disorders.

NHLBI-supported research has led to many advances in medical knowledge and care. For example, this research has uncovered some of the causes of heart diseases and conditions, as well as ways to prevent or treat them.

Many more questions remain about heart diseases and conditions, including heart attacks. The NHLBI continues to support research aimed at learning more about heart attacks. For example, NHLBI-supported research includes studies that explore:

• How new therapies can help treat heart attacks and improve quality of life for people who have had heart attacks
• The benefits of using certain tests, such as cardiac MRI, to evaluate people who have had heart attacks
• The factors that may play a role in causing heart attacks in women younger than 55 years of age

Much of this research depends on the willingness of volunteers to take part in clinical trials. Clinical trials test new ways to prevent, diagnose, or treat various diseases and conditions.

For example, new treatments for a disease or condition (such as medicines, medical devices, surgeries, or procedures) are tested in volunteers who have the illness. Testing shows whether a treatment is safe and effective in humans before it is made available for widespread use.

By taking part in a clinical trial, you can gain access to new treatments before they're widely available. You also will have the support of a team of health care providers, who will likely monitor your health closely. Even if you don't directly benefit from the results of a clinical trial, the information gathered can help others and add to scientific knowledge.

If you volunteer for a clinical trial, the research will be explained to you in detail. You'll learn about treatments and tests you may receive, and the benefits and risks they may pose. You'll also be given a chance to ask questions about the research. This process is called informed consent.

If you agree to take part in the trial, you'll be asked to sign an informed consent form. This form is not a contract. You have the right to withdraw from a study at any time, for any reason. Also, you have the right to learn about new risks or findings that emerge during the trial.

For more information about clinical trials related to heart attacks, talk with your doctor. You also can visit the following Web sites to learn more about clinical research and to search for clinical trials:

• http://clinicalresearch.nih.gov
• www.clinicaltrials.gov
• www.nhlbi.nih.gov/studies/index.htm
• www.researchmatch.org

Links to Other Information About Heart Attacks

NHLBI Resources

• "Aim for a Healthy Weight" Patient Booklet
• Angina (Health Topics)
• Atherosclerosis (Health Topics)
• Cardiac Rehabilitation (Health Topics)
• Cardiovascular Information for the Public
• Coronary Angioplasty (Health Topics)
• Coronary Artery Bypass Grafting (Health Topics)
• Coronary Heart Disease/Coronary Artery Disease (Health Topics)
• Coronary Heart Disease Risk Factors (Health Topics)
• "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." Wallet Card
• Heart Disease in Women (Health Topics)
• Keep the Beat™ Deliciously Healthy Eating
• "Learn What a Heart Attack Feels Like—It Could Save Your Life"
• Metabolic Syndrome (Health Topics)
• Overweight and Obesity (Health Topics)
• Physical Activity and Your Heart (Health Topics)
• Smoking and Your Heart (Health Topics)
• Story of Success: Conquering Cardiovascular Disease
• "Your Guide to Physical Activity and Your Heart"
• "Your Guide to a Healthy Heart"
• "Your Guide to Living Well With Heart Disease"

Non-NHLBI Resources

• Coronary Artery Disease (MedlinePlus)
• Angina (MedlinePlus)
• Heart Attack (MedlinePlus)
• Angina: Interactive Tutorial (MedlinePlus)
• Heart Attack: Interactive Tutorial (MedlinePlus)

Clinical Trials

• Clinical Trials (Health Topics)
• Current Research (ClinicalTrials.gov)
• NHLBI Clinical Trials
• NIH Clinical Research Trials and You (National Institutes of Health)
• ResearchMatch (funded by the National Institutes of Health)

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