cardiomyopathy (DCM) the main pumping chambers of the heart are enlarged
(dilated) and contract poorly. This results in less blood being pumped around
the body which fails to meet the body’s demand. This is known as heart failure.
There can be a build up of fluid in the lungs and under the skin, which can
cause breathlessness and swelling of the legs and abdomen.
specific cause for DCM can be found in about half of patients. In the other
half, however, the cause remains uncertain. The commonest causes of DCM in the
western world include coronary artery disease (‘furring’ of arteries to the
heart), which may lead to reduced blood flow to the heart muscle and a weak
CRY Consultant Cardiologist
Professor Sanjay Sharma
about dilated cardiomyopathy
Other common causes include
longstanding high blood pressure, excessive alcohol intake and heart valve
disease. Less common causes include viral infections; autoimmune diseases (i.e.
the body’s own defences mistakenly attack the heart muscle cells, resulting in
damage to the heart muscle); deficiency of several vitamins; inherited
disorders; and other rare
Normally the body’s immune system provides a defence against infection.
Occasionally however, for reasons that are uncertain, the immune system may be
activated mistakenly, and begin to attack itself. Viruses are believed to be a common
cause or trigger of the auto immune process which is seen in several conditions
including rheumatoid arthritis where the joints are damaged; juvenile onset
diabetes mellitus where the pancreas is damaged; and the thyroiditis where the
thyroid gland may be involved. In these autoimmune conditions, antibodies
circulating in the blood develop in the tissue or organ which is being attacked.
In dilated cardiomyopathy, antibodies against the heart are found in
approximately 30% of patients and in a similar proportion of the asymptomatic
relatives. This and other evidence suggests that an autoimmune component may
play an important part in the development and progression of dilated cardiomyopathy. The significance of the cardiac antibody in asymptomatic first
degree relatives is under study; in other conditions (diabetes) the presence of
the antibody in asymptomatic relatives identifies those at risk of developing
In at least 25% of people with DCM in whom no other cause can
be found, other family members can show signs of it and it has therefore been
inherited. Currently, around a quarter of inherited DCM can be explained by
finding the underling genetic problem (mutation). This does require testing for
many different genes, which is rarely done because of the expense. One gene,
Lamin AC, is often tested for because it is found most commonly and can be
associated with a higher risk of arrhythmia.
There is a form of DCM, known as ‘post-partum cardiomyopathy’,
which develops during late pregnancy and in the period shortly following
childbirth. The cause is uncertain, but it is believed that the extra strain of
pregnancy on the heart may trigger the development of the condition.
Symptoms can depend upon how severe the condition is, but
people may suffer none at all yet still carry signs of DCM.
Shortness of breath is common and can become worse with
exertion. When severe, it can be present at rest or even when lying flat in
bed - which may wake the person up at night. They may feel more comfortable
sitting-up in bed by adding extra pillows.
Lack of energy and tiring easily.
Ankle swelling, called oedema, which can worsen to affect
the thighs, back and abdomen.
Palpitations can occur and means that the person becomes
aware of their heartbeat due to an abnormal heart rhythm. The heart can
either beat irregularly, too rapidly (tachycardia) or too slowly (bradycardia).
A doctor will take a detailed history and perform an
examination. An ECG
should be performed, followed by an
ECHO. The ECHO
will measure the size of the heart and how well it pumps. If there is any
suspicion of DCM then other tests will often include an
exercise ECG - either
on a treadmill or a bicycle - or a 24-hour tape recording, as it is also
important to detect arrhythmias which may not display any symptoms. Finally,
depending on each individual case, further investigations may be necessary.
It is recommended that when familial or inherited DCM is identified in a family member, those first
degree blood relatives where the condition is NOT identified should
return for repeat testing every 2 - 5 years
until the age of 60 (although the exact frequency of repeat testing will vary
according to individual circumstances - e.g. number of family members identified
with DCM, presence of symptoms, etc).
Treatment aims to improve the symptoms of heart failure;
prevent complications - particularly those arising from the development of
arrhythmias; improve the heart function; and prolong life. Changes in lifestyle
may be important in the treatment of DCM. A doctor may discuss the following
cardiovascular risk factors:
Stop smoking with the help of smoking cessation clinics.
To improve dietary habits in order to lose weight, reduce the
cholesterol and the salt in the diet. An expert dietician’s review can
be very helpful.
Good control of the blood sugar if diabetic.
To monitor and treat high blood pressure.
intake to the minimum possible. Advice is that no more than a small glass,
preferably of red wine, should be consumed in a day.
Limiting fluid intake according to a doctor or specialist
Daily weighings using a reliable scale. Sudden increases
in weight may be a sign of fluid build-up and may act as a warning sign.
Medicines are the main treatment for heart failure. This includes water tablets
(diuretics) to get rid of excess fluid, Angiotensin Converting Enzyme inhibitors
(ACE-I), spironolactone and beta-blockers. Other drugs may be necessary should
Unless there is a reason for someone not being able to take ACE-I and
beta-blockers, every patient with significant DCM should be on them.
If a patient remain breathless or unwell, further treatment may be necessary.
This may include the insertion of specialised pacemakers under the skin that
help the heart beat more efficiently. This is known as resynchronisation
therapy. If heart pump function becomes badly affected, an
ICD may also be offered to treat dangerous arrhythmias and prolong life. The
ICD may also be able to ‘resynchronise’ the heart.
If a patient still does not respond to the above treatments
they may be referred to a specialist centre for cardiac transplantation. Strict
criteria apply to the selection of patients in order to assure a successful
transplantation. All immediate blood relatives of patients diagnosed with DCM of
an unknown cause should be screened to exclude the condition.