Heart Attack




What Is a Heart Attack?

A heart attack occurs when the supply of blood and oxygen to an area of heart muscle is blocked, usually by a clot in a coronary artery. Often, this blockage leads to arrhythmias (irregular heartbeat or rhythm) that cause a severe decrease in the pumping function of the heart and may bring about sudden death. If the blockage is not treated within a few hours, the affected heart muscle will die and be replaced by scar tissue.

A heart attack is a life-threatening event. Everyone should know the warning signs of a heart attack and how to get emergency help. Many people suffer permanent damage to their hearts or die because they do not get help immediately.

Each year, more than a million persons in the U.S. have a heart attack and about half (515,000) of them die. About one-half of those who die do so within 1 hour of the start of symptoms and before reaching the hospital.

Emergency personnel can often stop arrhythmias with emergency CPR (cardiopulmonary resuscitation), defibrillation (electrical shock), and prompt advanced cardiac life support procedures. If care is sought soon enough, blood flow in the blocked artery can be restored in time to prevent permanent damage to the heart. Yet, most people do not seek medical care for 2 hours or more after symptoms begin. Many people wait 12 hours or longer.

Other Names for Heart Attack

What Causes a Heart Attack?

Most heart attacks are caused by a blood clot that blocks one of the coronary arteries (the blood vessels that bring blood and oxygen to the heart muscle). When blood cannot reach part of your heart, that area starves for oxygen. If the blockage continues long enough, cells in the affected area die.

Coronary Artery Disease (CAD) is the most common underlying cause of a heart attack. CAD is the hardening and narrowing of the coronary arteries by the buildup of plaque in the inside walls (atherosclerosis). Over time, plaque buildup in the coronary arteries can:
  • Narrow the arteries so that less blood flows to the heart muscle
  • Completely block the arteries and the flow of blood
  • Cause blood clots to form and block the arteries.
A less common cause of heart attacks is a severe spasm (tightening) of the coronary artery that cuts off blood flow to the heart. These spasms can occur in persons with or without CAD. Artery spasm can sometimes be caused by:
  • Taking certain drugs, such as cocaine
  • Emotional stress
  • Exposure to cold
  • Cigarette smoking.
What Makes a Heart Attack More Likely?

Certain factors make it more likely that you will develop CAD and have a heart attack. These are called risk factors. Risk factors you cannot change include:
  • Your age
    • Men: over age 45
    Women: over age 55
  • Having a family history of early heart disease
    • Heart disease diagnosed in father or brother before age 55
    Heart disease diagnosed in mother or sister before age 65
  • Having a personal history of CAD
    • Angina
    A previous heart attack
    A surgical procedure (angioplasty, heart bypass) to increase blood flow to your heart.
Risk factors that you can change include:
  • Smoking
  • High blood pressure
  • High blood cholesterol
  • Obesity
  • Being physically inactive
  • Diabetes (high blood sugar)
What Are the Signs and Symptoms of a Heart Attack?

The warning signs and symptoms of a heart attack can include:
  • Chest discomfort: Most heart attacks involve discomfort in the center of the chest that lasts for more than a few minutes, or goes away and comes back. The discomfort can feel like uncomfortable pressure, squeezing, fullness, or pain. Heart attack pain can sometimes feel like indigestion or heartburn.
  • Discomfort in other areas of the upper body: Can include pain, discomfort, or numbness in one or both arms, the back, neck, jaw, or stomach.
  • Shortness of breath: Often comes along with chest discomfort. But it also can occur before chest discomfort.
  • Other symptoms: May include breaking out in a cold sweat, having nausea and vomiting, or feeling light-headed or dizzy.
Signs and symptoms vary from person to person. In fact, if you have a second heart attack, your symptoms may not be the same as for the first heart attack. Some people have no symptoms. This is called a "silent" heart attack. The symptoms of angina can be similar to those of a heart attack. If you have angina and notice a change or a worsening of your symptoms, talk with your doctor right away.

How Can I Prevent a Heart Attack?

Most heart attacks are caused by coronary artery disease (CAD). You can help prevent a heart attack by knowing about your risk factors for CAD and heart attack and taking action to lower your risks.

You can lower your risk of having a heart attack, even if you have already had a heart attack or are told that your chances of having a heart attack are high.

To prevent a heart attack, you will most likely need to make lifestyle changes. You may also need to get treatment for conditions that raise your risk.

Prevent a Second Heart Attack: If you have already had a heart attack, it is very important to follow your doctor's advice to prevent a second heart attack:
  • Make lifestyle changes as directed
  • Take your medications as directed
  • Follow any other treatment recommended by your doctor, such as cardiac rehabilitation.
By taking these steps, you can prevent or reduce the chance of another heart attack and related complications, such as heart failure.

Make sure that you have an emergency action plan in case you have signs of a second heart attack. Talk to your doctor about making your plan, and talk with your family about it. The plan should include:
  • The signs and symptoms of a heart attack.
  • Instructions for the prompt use of aspirin and nitroglycerin.
  • How to access emergency medical services in your community.
  • The location of the nearest hospital that offers 24-hour emergency heart care.
Credit: National Institute of Health.
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