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Facts About Cardiomyopathy
Cardiomyopathy is a disease of the heart muscle. The heart
loses its ability to pump blood and, in some instances, heart
rhythm is disturbed, leading to irregular heartbeats, or
arrhythmias. Usually, the exact cause of the muscle damage is
Cardiomyopathy differs from many other heart disorders in a
couple of ways. First, the types not related to coronary
atherosclerosis are fairly uncommon. Cardiomyopathy affects
about 50,000 Americans. However, the condition is a leading
reason for heart transplantation.
Second, unlike many other forms of heart disease that affect
middle-aged and older persons, certain types of cardiomopathies
can, and often do, occur in the young. The condition tends to
be progressive and sometimes worsens fairly quickly.
As noted, there are various types of cardiomyopathy. These fall
into two major categories: "ischemic" and "nonischemic"
- Ischemic cardiomyopathy typically refers to heart muscle
damage that results from coronary artery disease, such as heart
attack, and will not be discussed here (see page 8 on how to get
information on the disorder).
- Nonischemic cardiomyopathy includes several types. The
three main types are covered in this fact sheet. They are:
dilated, hypertrophic, and restrictive. The name of each
describes the nature of its muscle damage.
Dilated (Congestive) Cardiomyopathy
By far the most common type of nonischemic cardiomyopathy, the
dilated (stretched) form occurs when disease-affected muscle
fibers lead to enlargement, or dilation, of one or more chambers
of the heart. This weakens the heart's pumping ability. The
heart tries to cope with the pumping limitation by further
enlarging and stretching--a process known as "compensation."
Dilated cardiomyopathy occurs most often in middle-aged people
and more often in men than women. However, the disease has been
diagnosed in people of all ages, including children.
In most cases, the disease is idiopathic --a specific cause for
the damage is never identified.
But some factors have been linked to the disease's occurrence.
For instance, alcohol has a direct suppressant effect on the
heart. Dilated cardiomyopathy can be caused by chronic,
excessive consumption of alcohol, particularly in combination
with dietary deficiencies. Also, dilated cardiomyopathy
occasionally occurs as a complication of pregnancy and
childbirth. Other factors are: various infections, mostly
viral, which lead to an inflammation of the heart muscle
(myocarditis); toxins (such as cobalt, once used in beers, for
instance); and, rarely, heredity.
Some drugs, used to treat a different medical condition, also
can damage the heart and produce dilated cardiomyopathy. Such
drugs include doxorubicin and daunorubicin, both used to treat
Whatever the cause, the clinical and pathological manifestations
of dilated cardiomyopathy are usually the same.
Dilated cardiomyopathy can be present for several years without
causing significant symptoms. With time, however, the enlarged
heart gradually weakens.
This condition is commonly called "heart failure," and it is the
hallmark of dilated cardiomyopathy. Typical signs and symptoms
of heart failure include: fatigue; weakness; shortness of
breath, sometimes severe and accompanied by a cough,
particularly with exertion or when lying down; and swelling of
the legs and feet, resulting from fluid accumulation that may
also affect the lungs (congestion) and other parts of the body.
It also produces abnormal weight gain. (The cough and
congestion mimic and, therefore, can be misdiagnosed as
pneumonia or acute bronchitis. Also, heart failure is often
from heart disease other than cardiomyopathy.)
Because of the congestion, some physicians use the older term
"congestive cardiomyopathy" to refer to dilated cardiomyopathy.
In advanced stages of the disease, the congestion may cause pain
in the chest or abdomen.
In advanced stages, some patients develop irregular heartbeats,
which can be serious and even life threatening.
Once symptoms appear, the condition may be tentatively diagnosed
based on a physical examination and a patient's medical history.
More often, though, further examination is needed to
differentiate dilated cardiomyopathy from other causes of heart
A firm diagnosis typically requires a chest x ray to show
whether the heart is enlarged, an electrocardiogram to reveal
any abnormal electrical activity of the heart, and an
echocardiogram, which uses sound waves to produce pictures of
Other, more specific tests may also be needed. These include:
- A radionuclide ventriculogram. This involves injecting
low-dose radioactive material (usually equal to that in a set of
chest x rays) into a vein, through which it flows to the heart.
Pictures are generated by a special camera to show how well the
heart is functioning.
- A Cardiac catheterization. In this procedure, a thin
plastic tube is inserted through a blood vessel until it reaches
the heart. A dye is injected and x rays taken to assess the
heart's structure and function.
Since dilated cardiomyopathy is hard to diagnose early, it is
rarely treated in its beginning stage.
The goal of treatment is to relieve any complicating factor, if
known, control the symptoms, and stop the disease's progression.
However, no cure now exists.
Therapy begins with the elimination of obvious risk factors,
such as alcohol consumption. Weight loss and dietary changes,
especially salt restriction, may also be advised.
Drugs used to treat the condition include:
Also, patients with irregular heartbeats may be put on any
of various drugs to control the rhythm.
- Diuretic, which reduce excess fluid in the body;
- Vasodilators, such as angiotensin-converting enzyme (ACE) inhibitors,
which relax blood vessels, helping to lower blood
pressure and reducing the effort needed by the heart to pump
blood through the body;
- Digitalis, which helps to improve pumping action and
regulate heartbeat; and,
- Calcium blockers or beta blockers, which may be used in
some patients to help regulate heartbeat and to alter the work
of the heart muscle.
In critical cases where the condition is advanced and the
patient does not sufficiently respond to other treatments, a
heart transplantation may be needed. The patient's heart is
replaced with a donor heart. Most heart transplant recipients
are under age 60 and in good health other than their diseased
Course of the disease
As the heart enlarges, it steadily decreases its efficiency in
pumping blood and the amount of blood it can pump. As a result,
some patients cannot perform even simple physical activities.
However, the disease also may remain fairly stable for years,
especially with treatment and regular evaluation by a physician.
Unfortunately, by the time it is diagnosed, the disease often
has reached an advanced stage and heart failure has occurred.
Consequently, about 50 percent of patients with dilated
cardiomyopathy live 5 years once heart failure is diagnosed;
about 25 percent live 10 years after such a diagnosis.
Typically, patients die from a continued decline in heart muscle
strength, but some die suddenly of irregular heartbeats.
For patients with advanced disease, heart transplantation
greatly improves survival: 75 percent of patients live 5 years
after a transplantation. However, in the United States, the
scarcity of donor hearts limits the number of transplantations
to about 2,000 persons a year. Those who qualify for heart
transplantation often have to wait months, or even years, for a
suitable donor heart. Some patients with dilated cardiomyopathy
die awaiting a transplant but, according to recent studies,
others improve enough from aggressive medical treatment to be
taken off the waiting list.
Also, some critically ill cardiomyopathy patients with declining
heart function use a small, implanted mechanical pump as a
bridge to transplantation. Called left ventricular assist devices (LVADs),
these pumps take over part or virtually all of the heart's blood pumping activity. The devices provided only
temporary assistance and are not now used as substitutes for
The second most common form of heart muscle disease is
hypertrophic cardiomyopathy. Physicians sometimes call it by
other names: idiopathic hypertrophic subaortic stenosis (IHSS),
asymmetrical septal hypertrophy (ASH), or hypertrophic
obstructive cardiomyopathy (HOCM).
In hypertrophic cardiomyopathy, the growth and arrangement of
muscle fibers are abnormal, leading to thickened heart walls.
The greatest thickening tends to occur in the left ventricle
(the heart's main pumping chamber), especially in the septum,
the wall that separates the left and right ventricles. The
thickening reduces the size of the pumping chamber and obstructs
blood flow. It also prevents the heart from properly relaxing
between beats and so filling with blood. Eventually, this
limits the pumping action.
Hypertrophic cardiomyopathy is a rare disease, occurring in no
more than 0.2 percent of the U.S. population. It can affect men
and women of all ages. Symptoms can appear in childhood or
Most cases of hypertrophic cardiomyopathy are inherited.
Because of this, a patient's family members often are checked
for signs of the disease, although the signs may be much less
evident or even absent in them. In other cases, there is no
Many patients have no symptoms. For those who do, the most
common are breathlessness and chest discomfort. Other signs are
fainting during physical activity, strong rapid heartbeats that
feel like a pounding in the chest, and fatigue, especially with
In some cases, the first and only manifestation of hypertrophic
cardiomyopathy is sudden death, caused by a chaotic heartbeat.
The heart's lower chambers beat so chaotically and fast that no
blood is pumped. Instead of beating, the heart quivers.
In advanced stages of the disease, patients may have severe
heart failure and its associated symptoms, including fluid
accumulation or congestion.
By listening through a stethoscope, a physician may hear the
abnormal heart sounds characteristic of hypertrophic cardiomyopathy
The electrocardiogram (EKG, or ECG) may help
diagnose the condition by detecting changes in the electrical
activity of the heart as it beats.
Echocardiography is one of the best tools for diagnosing
hypertrophic cardiomyopathy. It uses sound waves to detect the
extent of muscle-wall thickening and to assess the status of the
Physicians also may request radionuclide studies to gather added
information about the disease's effect on how the heart is
Other tests that also may provide useful information are the
chest x ray, cardiac catheterization, and a heart muscle biopsy.
Treatments for hypertrophic cardiomyopathy vary but can include
Course of the disease
- Lifestyle changes. Patients with serious electrical and
blood-flow abnormalities must be less physically active.
- Medications. Various drugs are used to treat the disease.
They include beta blockers (to ease symptoms by slowing the
heart's pumping action), calcium channel blockers (to relax the
heart and reduce the blood pressure in it), antiarrhythmic
medications, and diuretics (to ease heart failure symptoms).
However, drugs do not work in all cases or may cause adverse
side effects, such as fluid in the lungs, very low blood
pressure, and sudden death. Then, other treatment, such as a
pacemaker or surgery, may be needed.
- Pacemakers. These change the pattern and decrease the
force of the heart's contractions. The pacemaker can reduce the
degree of obstruction and so relieve symptoms. A pacemaker
needs to be carefully monitored after its insertion in order to
properly adjust the electrical impulse. Some patients who have
a pacemaker inserted feel no relief and go on to have heart
- Surgery. This usually calls for removal of part of the
thickened septum (the muscle wall separating the chambers) that
is blocking the blood flow. Sometimes, surgery also must
replace a heart valve--the mitral valve, which connects the left
ventricle and the left atrium, the upper chamber that receives
oxygen-rich blood from the lungs.
Surgery to remove the thickening eases symptoms in about 70
percent of patients but results in death in about 1 to 3 percent
of patients. Also, about 5 percent of those who have surgery
develop a slow heartbeat, which is then corrected with a
The course of the disease varies. Many patients remain stable;
some improve; some worsen in symptoms and lead severely
restricted lives. Patients may need drug treatment and careful
medical supervision for the rest of their lives.
Hypertrophic cardiomyopathy patients also are at risk of sudden
death. About 2 to 3 percent die each year because the heart
suddenly stops beating. This cardiac arrest is brought on by an
abnormal heartbeat. Over 10 years, the risk of sudden death can
be 20 percent or more.
Restrictive cardiomyopathy is rare in the United States and most
other industrial nations. In this disease, the walls of the
ventricles stiffen and lose their flexibility due to
infiltration by abnormal tissue. As a result, the heart cannot
fill adequately with blood and eventually loses its ability to
Restrictive cardiomyopathy typically results from another
disease, which occurs elsewhere in the body. In the United
States, restrictive cardiomyopathy is most commonly related to
the following: amyloidosis, in which abnormal protein fibers
(amyloid) accumulate in the heart's muscle; sarcoidosis, an
inflammatory disease that causes the formation of small lumps in
organs; and hemochromatosis, an iron overload of the body,
usually due to a genetic disease.
In general, restrictive cardiomyopathy does not appear to be
inherited; however, some of the diseases that lead to the
condition are genetically transmitted.
Typical signs of the condition include symptoms of congestive
heart failure: weakness, fatigue, and breathlessness. Swelling
of the legs, caused by fluid retention, occurs in a significant
number of patients. Other symptoms include nausea, bloating,
and poor appetite, probably because of the retention of fluid
around the liver, stomach, and intestines.
A physician may suspect restrictive cardiomyopathy based on a
patient's symptoms and the presence of another disease. Although
symptoms of congestive heart failure may predominate, the size
of the heart remains relatively small, unlike other
Diagnostic information comes from an electrocardiogram or any of
several imaging studies that provide pictures of the heart.
These include echocardiography, magnetic resonance imaging, and
A definite diagnosis usually requires cardiac catheterization
studies or a biopsy, in which a tiny piece of tissue--including
heart muscle--is removed for laboratory analysis.
Restrictive cardiomyopathy has no specific treatment. The
underlying disease that leads to the heart problem also may not
In general, the use of traditional heart drugs has been limited
in this cardiomyopathy, although diuretics may help control
In rare cases, surgery is sometimes used to try to improve blood
flow into the heart.
Course of the disease
The condition is similar to dilated cardiomyopathy and tends to
worsen with time. Only about 30 percent of patients survive
more than 5 years after diagnosis.
Future advances in the diagnosis and treatment of cardiomyopathy
depend on a better understanding of the disease process and why
heart muscle is damaged. A lot of research is under way to
identify these processes and whether they can be halted or even
reversed. Much of the research is conducted at or supported by
the National Heart, Lung, and Blood Institute (NHLBI).
Promising clues came from investigators at and supported by the
NHLBI who discovered some of the genes responsible for
hypertrophic cardiomyopathy. Their work represents an important
first step in understanding how the disease is transmitted and
how it progresses.
Researchers also are trying to determine the best use of
currently available treatments, especially drug therapies.
Drugs useful for other conditions may help treat cardiomyopathy.
For example, drugs effective in treating high blood pressure
also help manage heart failure and irregular heartbeats.
Additionally, much work has been--and continues to be--done on
identifying factors that increase or decrease the risk of death
for persons with cardiomyopathy. Knowing which patients are at
the greatest risk is very important in determining the best
approach to evaluation and treatment of their condition.
The development of improved treatments for cardiomyopathy,
however, awaits still more research and a better understanding
of the disease process.
Angiotensin converting enzyme (ACE) inhibitor--A drug used to
decrease pressure inside blood vessels.
Arrhythmia--An irregular heartbeat.
Beta blocker--A drug used to slow the heart rate and reduce
pressure inside blood vessels. It also can regulate heart
Calcium channel blocker (or calcium blocker)--A drug used to
relax the blood vessel and heart muscle, causing pressure inside
blood vessels to drop. It also can regulate heart rhythm.
Cardiac arrest--A sudden stop of heart function. See also
Cardiac catheterization--A procedure in which a thin, hollow tube is inserted into a blood vessel. The tube is then advanced
through the vessel into the heart, enabling a physician to study
the heart and its pumping activity.
Cardiomyopathy--A disease of the heart muscle (myocardium).
Congestion--Abnormal fluid accumulation in the body, especially
Digitalis--A drug used to increase the force of the heart's
contraction and to regulate specific irregularities of heart
Dilated cardiomyopathy--Heart muscle disease that leads to
enlargement of the heart's chambers, robbing the heart of its
Diuretic--A drug that helps eliminate excess body fluid; usually
used in the treatment of high blood pressure and heart failure.
Dyspnea--Shortness of breath.
Echocardiography--A test that bounces sound waves off the heart
to produce pictures of its internal structures.
Edema--Abnormal fluid accumulation in body tissues.
Electrocardiogram (EKG or ECG)--Measurement of electrical
activity during heartbeats.
Heart failure--Loss of pumping ability by the heart, often
accompanied by fatigue, breathlessness, and excess fluid
accumulation in body tissues.
Hypertrophic cardiomyopathy--Heart muscle disease that leads to
thickening of the heart walls, interfering with the heart's
ability to fill with and pump blood.
Idiopathic--Results from an unknown cause.
Left ventricular assist device (LVAD)--A mechanical device used
to increase the heart's pumping ability.
Pulmonary congestion (or edema)--Fluid accumulation in the lungs.
Restrictive cardiomyopathy--Heart muscle disease in which the
muscle walls become stiff and lose their flexibility.
Septum--In the heart, a muscle wall separating the chambers.
Sudden death--Cardiac arrest caused by an irregular heartbeat.
The term "death" is somewhat misleading, because some patients
Ventricles--The two lower chambers of the heart. The left
ventricle is the main pumping chamber in the heart.
Ventricular fibrillation--Rapid, irregular quivering of the
heart's ventricles, with no effective heartbeat.
For More Information
For more information, contact the NHLBI Information Center, a
service of the NHLBI and the National Institutes of Health. The
Information Center provides information to health professionals,
patients, and the public about the treatment, diagnosis, and
prevention of heart, lung, and blood diseases.
NHLBI Information Center
P.O. Box 30105
Bethesda, MD 20824-0105
Telephone: (301) 251-1222
Fax: (301) 251-1223
Or check the NHLBI site on
the World Wide Web at: http://www.nhlbi.nih.gov/nhlbi/nhlbi.htm
Information provided by the NIH.