Overview

What is a heart attack?

A heart attack occurs when blood flow to the heart is blocked. Without blood and the oxygen it carries, part of the heart starts to die. A heart attack doesn't have to be deadly. Quick treatment can restore blood flow to the heart and save your life.

Your doctor might call a heart attack a myocardial infarction, or MI. Your doctor might also use the term acute coronary syndrome for your heart attack or unstable angina.

What is angina, and why is unstable angina a concern?

Angina (say "ANN-juh-nuh" or "ann-JY-nuh") is a type of chest pain or discomfort that occurs when there is not enough blood flow to the heart. Angina can be dangerous. So it is important to pay attention to chest pain, know what is typical for you, learn how to control it, and understand when you need to get treatment.

There are two types of angina:

• Stable angina is chest pain that has a typical pattern. It happens when your heart is working harder and needs more oxygen, such as during exercise. The pain goes away when you rest.
• Unstable angina is chest pain that is unexpected, and resting or taking nitroglycerin may not help. Your doctor will probably diagnose unstable angina if you are having chest pain for the first time or if your pain is getting worse, lasting longer, happening more often, or happening at rest.

Unstable angina is a warning sign that a heart attack may happen soon, so it requires treatment right away. But if you have any type of chest pain, see your doctor.

What causes a heart attack?

Heart attacks happen when blood flow to the heart is blocked. This usually occurs because fatty deposits called plaque have built up inside the coronary arteries, which supply blood to the heart. If a plaque breaks open, the body tries to fix it by forming a clot around it. The clot can block the artery, preventing the flow of blood and oxygen to the heart. See a picture of how plaque causes a heart attack.

This process of plaque buildup in the coronary arteries is called coronary artery disease, or CAD. In many people, plaque begins to form in childhood and gradually builds up over a lifetime. Plaque deposits may limit blood flow to the heart and cause angina. But too often, a heart attack is the first sign of CAD.

Things like intense exercise, sudden strong emotion, or illegal drug use (such as a stimulant, like cocaine) can trigger a heart attack. But in many cases, there is no clear reason why heart attacks occur when they do.

What are the symptoms?

The most common symptom of a heart attack is chest pain.

• Many people describe the pain as discomfort, pressure, squeezing, or heaviness in the chest.
• People often put their fist to their chest when they describe the pain.
• The pain may spread down the left shoulder and arm and to other areas, such as the back, jaw, neck, or right arm.

Many people also have at least one other symptom, such as:

• Pain in the upper belly, often mistaken for heartburn.
• Sweating.
• Nausea and vomiting.
• Trouble breathing.
• A feeling that their heart is racing or pounding (palpitations).
• Feeling weak or very tired.
• Feeling dizzy or fainting.

Not everyone has the classic symptom of chest pain during a heart attack. Women, older adults, and people with diabetes are slightly more likely to have other symptoms such as shortness of breath, nausea, back pain, or jaw pain.

What should you do if you think you are having a heart attack?

If you have symptoms of a heart attack, act fast. Quick treatment could save your life.

If you are having chest pain and your doctor has prescribed nitroglycerin for angina:

1. Take 1 dose of nitroglycerin and wait 5 minutes.
2. If the chest pain doesn't improve or it gets worse, call 911 or other emergency services. Describe your symptoms, and say that you could be having a heart attack.
3. Stay on the phone. The emergency operator will tell you what to do.
4. After you call for help, chew 1 adult-strength aspirin or 2 to 4 low-dose aspirin unless you cannot take aspirin because of allergy or some other reason. Aspirin helps keep blood from clotting, so it may help you survive a heart attack.

If you are having chest pain and you do not have nitroglycerin:

1. Call 911 or other emergency services now. Describe your symptoms, and say that you could be having a heart attack.
2. Stay on the phone. The emergency operator will tell you what to do.
3. After you call for help, chew 1 adult-strength aspirin or 2 to 4 low-dose aspirin unless you cannot take aspirin because of allergy or some other reason. Aspirin helps keep blood from clotting, so it may help you survive a heart attack.

The best choice is to go to the hospital in an ambulance. The paramedics can begin lifesaving treatments even before you arrive at the hospital. If you cannot reach emergency services, have someone drive you to the hospital right away. Do not drive yourself unless you have absolutely no other choice.

If you think you are having unstable angina but you are not sure, follow the steps listed above. Unstable angina can lead to a heart attack or death, so you need to have it checked right away.

How is a heart attack treated?

If you go to the hospital in an ambulance, treatment will be started right away to restore blood flow and limit damage to the heart. You may be given medicines, including:

• Aspirin (if you have not already taken some) and other medicines to prevent blood clots.
• Medicines that break up blood clots (thrombolytics). To work, these must be given within a few hours of the start of the heart attack.
• Medicines to decrease the heart's workload, ease pain, and treat abnormal heart rhythms, which can be life-threatening.

At the hospital, you will have tests, such as:

• Electrocardiogram (EKG or ECG) . An EKG can detect signs of poor blood flow, heart muscle damage, abnormal heartbeats, and other heart problems.
• Blood tests, including tests to see whether cardiac enzymes are high. Having these enzymes in the blood is usually a sign that the heart has been damaged.

If these tests show that you may be having a heart attack, you may have a cardiac catheterization. For this test, the doctor puts a thin, flexible tube (called a catheter) through an artery in the groin or arm and carefully guides it into the heart. (See a picture of catheter placement.) A dye is injected that makes the coronary arteries show up on a computer screen. The doctor then can see if the coronary arteries are blocked and how your heart is working.

If cardiac catheterization shows that an artery is blocked, the doctor may do angioplasty right away. The doctor guides the catheter into the narrowed artery, and a small balloon at the end of it is inflated. This widens the artery to help restore blood flow. Often a small wire-mesh tube called a stent is placed to keep the artery open. See a picture of angioplasty with stent placement.

Angioplasty, with or without a stent, is the preferred treatment for a heart attack. But if angioplasty is not available or cannot be done soon, “clot-busting” thrombolytic medicines may be used. Or the doctor may do emergency bypass surgery to redirect blood around the blocked artery.

After these treatments, medicines are given to prevent clots, reduce the heart’s workload, and lower cholesterol. These can help prevent another heart attack and heart failure. Most people who have had a heart attack take these and sometimes other medicines for the rest of their lives.

After you have had a heart attack, the chance that you will have another one is higher. Taking part in a cardiac rehab program helps lower this risk. A cardiac rehab program is designed for you and supervised by doctors and other specialists. It can help you learn how to eat a balanced diet and exercise safely to reduce your risk of more heart problems.

It is common to feel worried and afraid after a heart attack. But if you are feeling very sad or hopeless, ask your doctor about treatment. Getting treatment for depression may help you recover from a heart attack.

Can you prevent a heart attack?

Heart attacks are usually the result of heart disease, so taking steps to delay or reverse coronary artery disease can help prevent a heart attack. Heart disease is the number one killer of both men and women in the United States, so these steps are important for everyone.

To improve your heart health:

• Don't smoke, and avoid secondhand smoke. Quitting smoking can quickly reduce the risk of another heart attack or death.
• Eat a heart-healthy diet that includes plenty of fish, fruits, vegetables, beans, high-fiber grains and breads, and olive oil.
• Get regular exercise. Your doctor can suggest a safe level of exercise for you.
• Control your cholesterol and blood pressure.
• Manage your diabetes.
• Lower your stress level. Stress can damage your heart.
• Take a daily aspirin if your doctor advises it.
• Get a flu shot every year.
• Take all of your medicines correctly. Taking medicine can lower your risk of having another heart attack or dying from coronary artery disease.
• Seek help to manage symptoms of depression.

More information How does the heart work? What do the coronary arteries do? How does atherosclerosis affect the heart? What happens when the heart doesn't get enough oxygen? Do women need to worry about heart disease? For more information about heart disease, see the topic Coronary Artery Disease.