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.

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 severe 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.