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.
Other Names for a Heart Attack
Myocardial infarction or MI
Acute myocardial infarction or AMI
Acute coronary syndrome
Coronary thrombosis
Coronary occlusion
What Causes a Heart Attack?
Most heart attacks occur as a result of
coronary artery disease (CAD). CAD is the buildup over time of a material
called plaque on the inner walls of the coronary arteries. Eventually, a
section of plaque can break open, causing a blood clot to form at the site. A
heart attack occurs if the clot becomes large enough to cut off most or all of
the blood flow through the artery.
Coronary Artery With Plaque
Buildup
The illustration shows a normal
artery with normal blood flow (figure A) and an artery containing plaque
buildup (figure B).
The blocked blood flow prevents oxygen-rich blood
from reaching the part of the heart muscle fed by the artery. The lack of
oxygen damages the heart muscle. If the blockage isn’t treated quickly,
the damaged heart muscle begins to die.
Heart attack also can occur due to problems with the
very small, microscopic blood vessels of the heart. This condition is called
microvascular disease. It’s believed to be more common in women than in
men.
Another less common cause of heart attack is a
severe spasm (tightening) of a coronary artery that cuts off blood flow through
the artery. These spasms can occur in coronary arteries that don’t have
CAD. It’s not always clear what causes a coronary artery spasm, but
sometimes it can be related to:
Taking certain drugs, such as cocaine
Emotional stress or pain
Exposure to extreme cold
Cigarette smoking
The animation below shows how a heart attack occurs.
Click the “start” button to play the animation. Written and spoken
explanations are provided with each frame. Use the buttons in the lower right
corner to pause, restart, or replay the animation, or use the scroll bar below
the buttons to move through the frames.
The animation shows how blood flow
is blocked in the heart, leading to a heart attack.
Who Is At Risk for a Heart Attack?
Certain risk factors make it more likely that you
will develop
coronary artery disease (CAD) and have a heart attack. Some
risk factors for heart attack can be controlled, while others can't.
Major risk factors for heart attack that you can
control include:
Age. Risk increases for men older than 45 years
and for women older than 55 years (or after menopause).
Family history of early CAD. Your risk increases
if your father or a brother was diagnosed with CAD before 55 years of age, or
if your mother or a sister was diagnosed with CAD before 65 years of age.
Certain CAD risk factors tend to occur together.
When they do, it’s called
metabolic
syndrome. In general, a person with metabolic syndrome is twice as likely
to develop heart disease and five times as likely to develop diabetes as
someone without metabolic syndrome.
What Are the Signs and Symptoms of a Heart Attack?
Not all heart attacks begin with a sudden, crushing
pain that is often shown on TV or in the movies. The warning signs and symptoms
of a heart attack aren’t the same for everyone. Many heart attacks start
slowly as mild pain or discomfort. Some people don’t have symptoms at all
(this is called a silent heart attack).
Chest Pain or Discomfort
The most common symptom of heart attack is chest
pain or 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.
It can be mild or severe. Heart attack pain can sometimes feel like indigestion
or heartburn.
The symptoms of
angina can be similar to the symptoms of a heart attack. Angina is pain in
the chest that occurs in people with
coronary artery disease, usually when they’re active. Angina pain
usually lasts for only a few minutes and goes away with rest. Angina that
doesn’t go away or that changes from its usual pattern (occurs more
frequently or occurs at rest) can be a sign of the beginning of a heart attack
and should be checked by a doctor right away.
Other Common Signs and Symptoms
Other common signs and symptoms that a person can
have during a heart attack include:
Upper body discomfort in one or both arms, the
back, neck, jaw, or stomach
Shortness of breath may often occur with or
before chest discomfort
Nausea (feeling sick to your stomach), vomiting,
lightheadedness or fainting, or breaking out in a cold sweat
Not everyone having a heart attack experiences the
typical symptoms. If you’ve already had a heart attack, your symptoms may
not be the same for another one. The more signs and symptoms you have, the more
likely it is that you’re having a heart attack.
Act Fast
Sometimes the signs and symptoms of a heart attack
happen suddenly, but they can also develop slowly, over hours, days, and even
weeks before a heart attack occurs.
Know the warning signs of a heart attack so you can
act fast to get treatment for yourself or someone else. The sooner you get
emergency help, the less damage there will be to your heart.
Call 9–1–1 for help within 5 minutes if
you think you may be having a heart attack or if your chest pain doesn’t
go away as it usually does when you take prescribed medicine.
Don’t drive yourself or anyone else to the
hospital. Call an ambulance so that medical personnel can begin life-saving
treatment on the way to the emergency room.
How Is a Heart Attack Diagnosed?
The diagnosis of heart attack is based on your
symptoms, your personal and family medical history, and the results of
diagnostic tests.
EKG (Electrocardiogram)
This test detects and records the electrical
activity of the heart. Certain changes in the appearance of the electrical
waves on an EKG are strong evidence of a heart attack. An
EKG
also can show if you’re having
arrhythmias
(abnormal heartbeats), which a heart attack (and other conditions) can cause.
Blood Tests
During a heart attack, heart muscle cells die and
burst open, letting certain proteins out in the bloodstream.
Blood
tests can measure the amount of these proteins in the bloodstream. Higher
than normal levels of these proteins in the bloodstream is evidence of a heart
attack.
Commonly used blood tests include troponin tests, CK
or CK–MB tests, and serum myoglobin tests. Blood tests are often repeated
to check for changes over time.
Coronary Angiography
Coronary
angiography is a special x-ray exam of the heart and blood vessels. It's
often done during a heart attack to help pinpoint blockages in the coronary
arteries.
The doctor passes a catheter (a thin, flexible tube)
through an artery in your arm or groin (upper thigh) and threads it to your
heart. This procedure—called
cardiac
catheterization—is part of coronary angiography.
A dye that can be seen on x ray is injected into the
bloodstream through the tip of the catheter. The dye lets the doctor study the
flow of blood through the heart and blood vessels.
If a blockage is found, another procedure, called
angioplasty,
may be used to restore blood flow through the artery. Sometimes during
angioplasty, the doctor will place a
stent
(a small mesh tube) in the artery to help keep the artery open.
How Is a Heart Attack Treated?
Early treatment can prevent or limit damage to the
heart muscle. Acting fast, at the first symptoms of heart attack, can save your
life. Medical personnel can begin diagnosis and treatment even before you get
to the hospital.
Certain treatments are usually started right away if
a heart attack is suspected, even before the diagnosis is confirmed. These
include:
Oxygen
Aspirin to prevent further blood clotting
Nitroglycerin, to reduce the workload on the
heart and improve blood flow through the coronary arteries
Treatment for chest pain
Once the diagnosis of heart attack is confirmed or
strongly suspected, treatments to try to restore blood flow to the heart are
started as soon as possible. Treatments include medicines and medical
procedures.
Medicines
A number of different kinds of medicines may be used
to treat heart attack. They include the following.
Thrombolytic Medicines
These medicines (also called clot busters) are used
to dissolve blood clots that are blocking the coronary arteries. To be most
effective, these medicines must be given within 1 hour after the start of heart
attack symptoms.
Beta Blockers
These medicines decrease the workload on your heart.
Beta blockers also are used to relieve chest pain or discomfort and to help
prevent additional heart attacks. Beta blockers also are used to correct
arrhythmias
(irregular heartbeats).
Angiotensin-Converting Enzyme (ACE) Inhibitors
These medicines lower blood pressure and reduce the
strain on your heart. They also help slow down further weakening of the heart
muscle.
Anticoagulants
These medicines thin the blood and prevent clots
from forming in your arteries.
Antiplatelet Medicines
These medicines (such as aspirin and clopidogrel)
stop platelets (a type of blood cell) from clumping together and forming
unwanted clots.
Other Medicines
Medicines may also be given to relieve pain and
anxiety, and to treat arrhythmias, which often occur during a heart attack.
Medical Procedures
If medicines can’t stop a heart attack, medical
procedures—surgical or nonsurgical—may be used. These procedures
include the following.
Angioplasty
This nonsurgical procedure can be used to open
coronary arteries that are blocked by a blood clot. During
angioplasty,
a catheter (a thin, flexible tube) with a balloon on the end is threaded
through a blood vessel to the blocked coronary artery. Then, the balloon is
inflated to push the plaque against the wall of the artery. This widens the
inside of the artery, restoring blood flow.
During angioplasty, a small mesh tube called a
stent
may be put in the artery to help keep it open. Some stents are coated with
medicines that help prevent the artery from becoming blocked again.
Coronary Artery Bypass Grafting
Coronary
artery bypass grafting is a surgery in which arteries or veins are taken
from other areas of your body and sewn in place to bypass (that is, go around)
blocked coronary arteries. This provides a new route for blood flow to the
heart muscle.
Treatment After You Leave the Hospital
Most people spend several days in the hospital after
a heart attack. When you leave the hospital, treatment doesn’t stop. At
home, your treatment may include daily medicines and
cardiac
rehabilitation (rehab). Your doctor may recommend lifestyle changes,
including quitting smoking, losing weight, changing your diet, and increasing
your physical activity, to lower your chances of having another heart attack.
Cardiac Rehabilitation
Your doctor may prescribe cardiac rehab to help you
recover from a heart attack and to help prevent another heart attack. Almost
everyone who has had a heart attack can benefit from rehab. The heart is a
muscle, and the right exercise will strengthen it.
But cardiac rehab isn’t only about exercise. It
also includes education, counseling, and learning about reducing your risk
factors. Rehab will help you learn the best way to take care of yourself after
having a heart attack and how to prevent having another one.
The cardiac rehab team may include doctors (your
family doctor, a cardiologist, and/or a surgeon), nurses, exercise specialists,
physical and occupational therapists, dietitians, and psychologists or other
behavioral therapists.
How Can a Heart Attack Be Prevented?
Lowering your risk factors for
coronary
artery disease (CAD) can help you prevent a heart attack. (See "Who Is At Risk for a Heart Attack?") Even if
you already have CAD, you can still take steps to lower your risk of heart
attack.
Reducing the risk of heart attack usually means
making healthy lifestyle choices. You also may need treatment for medical
conditions that raise your risk.
Healthy Lifestyle Choices
Healthy lifestyle choices to help prevent heart
attack include:
Following a low-fat diet rich in fruits and
vegetables. Pay careful attention to the amounts and types of fat in your diet.
Lower your salt intake. These changes can help lower
high
blood pressure and
high
blood cholesterol.
Doing physical activity to improve heart fitness.
Ask your doctor how much and what kinds of physical activity are safe for you.
Treat Related Conditions
In addition to making lifestyle changes, you can
help prevent heart attacks by treating conditions you have that make a heart
attack more likely:
High blood cholesterol. You may need medicine to
lower your cholesterol if diet and exercise aren't enough.
High blood pressure. You may need medicine to
keep your blood pressure under control.
Diabetes (high blood sugar). If you have
diabetes, control your blood sugar levels through diet and physical activity
(as your doctor recommends). If needed, take medicine as prescribed.
Have an Emergency Action Plan
Make sure that you have an
emergency action
plan in case you or someone else in your family has a heart attack. This is
especially important if you're at high risk or have already had a heart attack.
Talk with your doctor about the signs and symptoms
of heart attack, when you should call 9–1–1, and steps you can take
while waiting for medical help to arrive.
Life After a Heart Attack
Many people survive heart attacks and live active
and full lives. If you get help quickly, treatment can limit the damage to your
heart muscle. Less heart damage improves your chances for a better quality of
life after a heart attack.
Medical Followup
After a heart attack, you will need treatment for
coronary
artery disease to prevent another heart attack. Your doctor may recommend:
Lifestyle changes, such as quitting smoking,
following a healthy diet, increasing your physical activity, and losing weight,
if needed
After a heart attack, most people without chest pain
or discomfort or other complications can safely return to most of their normal
activities within a few weeks. Most can begin walking immediately. Sexual
activity also can begin within a few weeks for most patients. Discuss with your
doctor a safe schedule for returning to your normal activities.
If allowed by State law, driving can usually begin
within a week for most patients who don’t have chest pain or discomfort or
other complications. Each State has rules about driving a motor vehicle
following a serious illness. People with complications shouldn’t drive
until their symptoms have been stable for a few weeks.
Anxiety and Depression After a Heart Attack
After a heart attack, many people worry about having
another heart attack. Sometimes they feel depressed and have trouble adjusting
to the new lifestyle that’s needed to limit further heart trouble. Your
doctor may recommend medicine or professional counseling if you have depression
or anxiety. Physical activity can improve mental well-being, but you should
consult with your doctor before starting any fitness activities.
Risk of a Repeat Heart Attack
Once you’ve had a heart attack, you’re at
higher risk for another one. It’s important to know the difference between
angina
and a heart attack. The pain of angina usually occurs after exertion and goes
away in a few minutes when you rest or take medicine as directed. During a
heart attack, the pain is usually more severe than angina, and it doesn’t
go away when you rest or take medicine. If you don’t know whether your
chest pain is angina or a heart attack, call 9–1–1.
Remember, the symptoms of a second heart attack may
not be the same as those of a first heart attack. Don’t take a chance if
you’re in doubt. Always call 9–1–1 within 5 minutes if you or
someone you’re with has symptoms of a heart attack.
Unfortunately, most heart attack victims wait 2
hours or more after their symptoms begin before they seek medical help. This
delay can result in lasting heart damage or death.
Key Points
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.
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.
Unfortunately, many heart attack victims wait 2
hours or more after their symptoms begin before they seek medical help. This
delay can result in lasting heart damage or death.
If you think you or someone with you is having a
heart attack, call 9–1–1 right away.
Heart attacks occur most often as a result of a
condition called
coronary
artery disease (CAD).
Heart attack also can be caused by a condition
called microvascular disease, which involves the microscopic blood vessels of
the heart. Less commonly, a spasm (tightening) of a coronary artery can cause a
heart attack.
Certain risk factors increase the changes of
developing CAD and having a heart attack (for example, age, a family history of
CAD, smoking, and being
overweight
or obese). Some risk factors can’t be controlled, while others can.
The warning signs of heart attack aren’t
the same for everyone. However, common signs and symptoms of a heart attack
are:
Chest discomfort or pain—uncomfortable
pressure, squeezing, fullness, or pain in the center or 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.
Treatments for heart attack include medicines and
procedures to open blocked arteries (such as
angioplasty).
Lowering your risk for CAD can decrease your
chances of having a heart attack (or second heart attack). This usually
involves making healthy lifestyle choices and treating conditions related to
CAD such as
high
cholesterol,
high
blood pressure, overweight and obesity, and diabetes.
Most people are able to return to their normal
activities after a heart attack. Ask your doctor when you can resume daily
activities such as driving, exercise, work, sexual activity, strenuous
activities (for example, running or heavy lifting), and travel.
Many people survive heart attacks and live active
and full lives.
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