How a Heart Attack Happens

A heart attack happens if the flow of oxygen-rich blood to a section of heart muscle suddenly becomes blocked and the heart can't get oxygen. 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.

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.

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 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 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. It is important for you to know the most common symptoms of a heart attack and also remember these facts:

• Heart attacks can start slowly and cause only mild pain or discomfort. Symptoms can be mild or more intense and sudden. Symptoms also may come and go over several hours.
• People who have high blood sugar (diabetes) may have no symptoms or very mild ones.
• The most common symptom, in both men and women, is chest pain or discomfort.
• Women are somewhat more likely to have shortness of breath, nausea and vomiting, unusual tiredness (sometimes for days), and pain in the back, shoulders, and jaw.

Some people don't have symptoms at all. Heart attacks that occur without any symptoms or with very mild symptoms are called silent heart attacks.

Most Common Symptoms

 

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 for 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. The feeling can be mild or severe.
• 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.

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

Pay attention to these other possible symptoms of a heart attack:

• 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 symptoms or a change in the pattern of symptoms you already have (for example, if your symptoms become stronger or last longer than usual)

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.

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

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.
Any time you think you might 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, even if you are not sure whether you're having a heart attack. Here's why:

• Acting fast can save your life.
• An ambulance is the best and safest way to get to the hospital. Emergency medical services (EMS) personnel can check how you are doing and start life-saving medicines and other treatments right away. People who arrive by ambulance often receive faster treatment at the hospital. 
• The 9–1–1 operator or EMS technician can give you advice. You might be told to crush or chew an aspirin if you're not allergic, unless there is a medical reason for you not to take one. Aspirin taken during a heart attack can limit the damage to your heart and save your life.

Every minute matters. Never delay calling 9–1–1 to take aspirin or do anything else you think might help.