What Is a Heart Attack?
A heart attack occurs when blood flow to a section of heart muscle becomes
blocked. If the flow of blood isn’t restored quickly, the section of heart
muscle becomes damaged from lack of oxygen and begins to die.
Heart attack is a leading killer of both men and women in the United States.
But fortunately, today there are excellent treatments for heart attack that can
save lives and prevent disabilities. Treatment is most effective when started
within 1 hour of the beginning of symptoms. If you think you or someone you’re
with is having a heart attack, call 9–1–1 right away.
Overview
Heart attacks occur most often as a result of a condition called
coronary artery disease (CAD). In CAD, a fatty material called plaque (plak)
builds up over many years on the inside walls of the coronary arteries (the
arteries that supply blood and oxygen to your heart). Eventually, an area of
plaque can rupture, causing a blood clot to form on the surface of the plaque.
If the clot becomes large enough, it can mostly or completely block the flow of
oxygen-rich blood to the part of the heart muscle fed by the artery.
Heart With Muscle Damage and a Blocked Artery

Figure A is an overview of a heart and coronary artery
showing damage (dead heart muscle) caused by a heart attack. Figure B is a
cross-section of the coronary artery with plaque buildup and a blood clot.
During a heart attack, if the blockage in the coronary artery isn’t treated
quickly, the heart muscle will begin to die and be replaced by scar tissue. This
heart damage may not be obvious, or it may cause severe or long-lasting
problems.
Severe problems linked to heart attack can include heart
failure and life-threatening
arrhythmias (irregular heartbeats). Heart failure is a condition in which
the heart can’t pump enough blood throughout the body. Ventricular fibrillation
is a serious arrhythmia that can cause death if not treated quickly.
Get Help Quickly
Acting fast at the first sign of heart attack symptoms can save your life and
limit damage to your heart. Treatment is most effective when started within 1
hour of the beginning of symptoms.
The most common heart attack signs and symptoms are:
- Chest discomfort or pain—uncomfortable pressure, squeezing, fullness, or
pain in the center of the chest that can be mild or strong. This discomfort or
pain lasts more than a few minutes or goes away and comes back.
- Upper body discomfort in one or both arms, the back, neck, jaw, or
stomach.
- Shortness of breath may occur with or before chest discomfort.
- Other signs include nausea (feeling sick to your stomach), vomiting,
lightheadedness or fainting, or breaking out in a cold sweat.
If you think you or someone you know may be having a heart attack:
- Call 9–1–1 within a few minutes—5 at the most—of the start of symptoms.
- If your symptoms stop completely in less than 5 minutes, still call your
doctor.
- Only take an ambulance to the hospital. Going in a private car can delay
treatment.
- Take a nitroglycerin pill if your doctor has prescribed this type of
medicine.
Outlook
Each year, about 1.1 million people in the United States have heart attacks,
and almost half of them die. CAD, which often results in a heart attack, is the
leading killer of both men and women in the United States.
Many more people could recover from heart attacks if they got help faster. Of
the people who die from heart attacks, about half die within an hour of the
first symptoms and before they reach the hospital.
Medical
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