Dr. MJ Bazos MD,
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 never found.
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
•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
•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.
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 cancer.
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.
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
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 failure.
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 the heart.
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
•Diuretics, which reduce excess fluid in
•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.
Also, patients with irregular heartbeats may be
put on any of various drugs to control the rhythm.
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 heart.
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
Unfortunately, by the time
it is diagnosed, the disease often has reached an advanced stage and heart
failure has occurred. Consequently, about 50% of patients with dilated
cardiomyopathy live 5 years once heart failure is diagnosed; about 25% live 10
years after such a diagnosis.
Typically, patients die from a
continued decline in heart muscle strength, but some die suddenly of irregular
For patients with advanced
disease, heart transplantation greatly improves survival: 75% 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
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 heart transplantation.
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
cardiomyopathy is a rare disease, occurring in no more than 0.2% of the U.S.
population. It can affect men and women of all ages. Symptoms can appear in
childhood or adulthood.
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 clear
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 physical exertion.
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
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
may request radionuclide studies to gather added information about the disease's
effect on how the heart is pumping blood.
Other tests that also may provide useful
information are the chest x ray, cardiac catheterization, and a heart muscle
Treatments for hypertrophic
cardiomyopathy vary but can include the following: •Lifestyle changes.
Patients with serious electrical and blood-flow abnormalities must be less
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.
•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% of patients
but results in death in about 1% to 3% of patients. Also, about 5% of those who
have surgery develop a slow heartbeat, which is then corrected with a pacemaker.
Course of the Disease
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% 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% 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 pump properly.
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.
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
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 cardiomyopathies.
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 computed
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 be treatable.
In general, the use
of traditional heart drugs has been limited in this cardiomyopathy, although
diuretics may help control fluid accumulation.
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% of patients survive
more than 5 years after diagnosis.
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
Cardiac arrest—A sudden stop
of heart function. See also "sudden death."
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).
accumulation in the body, especially the lungs.
Digitalis—A drug used to increase
the force of the heart's contraction and to regulate specific irregularities of
cardiomyopathy—Heart muscle disease that leads to enlargement of the
heart's chambers, robbing the heart of its pumping ability.
Diuretic—A drug that helps eliminate
excess body fluid; usually used in the treatment of high blood pressure and
Echocardiography—A test that
bounces sound waves off the heart to produce pictures of its internal
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.
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
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.
muscle disease in which the muscle walls become stiff and lose their
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
lower chambers of the heart. The left ventricle is the main pumping chamber in
fibrillation—Rapid, irregular quivering of the heart's ventricles, with no