Dilated cardiomyopathy (DCM)

In dilated cardiomyopathy (DCM) the main pumping chambers of the heart are dilated and contract poorly. This results in a reduced volume of blood (low output) pumped around the body which fails to meet the body’s demand and features of what is commonly known as heart failure. There is a build up of fluid in the lungs and under the skin, which manifests as breathlessness and swelling of the legs and abdomen, respectively.

We are able to identify a specific cause for dilated cardiomyopathy in about 50% of patients. In the other 50%, however, the cause remains uncertain. The commonest causes of DCM in western societies includes coronary artery disease (narrowed coronary arteries) which may lead to reduced blood flow to the heart muscle and a heart attack resulting in ‘death’ of part of the muscle and a weak heart. 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 and other rare conditions.

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 individuals without symptoms is under study.

CRY Consultant Cardiologist Professor Sanjay Sharma talks about dilated cardiomyopathy (DCM) below. This video was published in 2011 – please note that life expectancy following a diagnosis of DCM is now (July 2017) much better than in 2011.

Pregnancy

There is a form of dilated cardiomyopathy which develops during late pregnancy and in the period shortly following childbirth. The cause is uncertain but it is believed that the additional demand of pregnancy on the heart may be triggering factor in the development of the condition.

Genetics

Recently it has become apparent that dilated cardiomyopathy is inherited in at least 25% of cases. All first-degree relatives of patients diagnosed with DCM of unknown cause (idiopathic) should be screened to exclude the condition. Evaluation of the family has potential to clarify the genetic contribution to the development of the condition within individual families.

What are the symptoms?

Symptoms depend on the stage and evolution of the condition.

  • Shortness of breath– This is a common symptom which becomes worse with exertion.  It is caused by the build-up of fluid and elevated pressure in the lungs. When severe, there may be marked breathlessness at rest or even when the patient lies in bed. Patients may feel more comfortable sitting-up in bed by adding extra pillows or may experience sudden bouts of breathlessness which wake them up at night.
  • Lack of energy – If the heart is not pumping well and the body is not getting enough blood the muscles are unable to contract normally and easily become tired.
  • Ankle swelling– When the right side of the heart fails to expel the blood it receives, the fluid builds up in the body tissues. This is called oedema and usually presents initially with swelling of the ankles which can then extend up to the thighs, back and abdomen.
  • Chest pain– This may occur at rest or during exercise. Though the cause of the pain is usually not clear, it is important to exclude significant coronary artery disease i.e. angina.
  • Irregular heart rhythm– Irregular heart rhythms are a common complication. The heart can either beat irregularly, too rapidly (tachycardia) or too slowly (bradycardia). Such arrhythmias are often asoociated with an uncomfortable awareness of the heart beat (palpitations) and/or accompanied by dizziness and fainting.

How is it diagnosed?

Your doctor will usually start by asking you some questions and examining you. An electrocardiogram (ECG) should be performed followed by an echocardiogram. The echocardiogram provides images of the heart with measurements of the size of the chambers as well as determination of how well they contract. It may also provide evidence of the cause of dilated cardiomyopathy. Exercise testing, either on a treadmill or a bicycle, should be performed to stress the heart. This test is particularly useful as symptoms and abnormal heart rhythms may not be obvious at rest and only become apparent during exertion. Monitoring the heart rhythm with a continuous tape recording is also important to detect arrhythmias which may not be symptomatic. It might be necessary for you to have further investigations.

Treatment and advice

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.

Lifestyle modification plays a pivotal role to DCM treatment. Your doctor may discuss the following things with you.

Reducing all 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 the patients is a diabetic.
To monitor and aggressively treat high blood pressure.
Regular exercise. The NHS provides exercise clinics run by expert nurses.
Limiting alcohol intake to the minimum possible. Current evidence suggest that no more than a small glass, preferably of red wine, should be consumed in a day.
Limiting fluid intake according to the physicians/specialist nurse advice.
Daily weighings using a reliable scale. Sudden, excessive increase in weight may be a sign of fluid built-up and may predate clinical signs by several days, acting as a warning sign.

Watch CRY’s myheart cardiologist, Dr Michael Papadakis talk about things to avoid with cardiomyopathy below.

The mainstay of heart failure treatment is drugs. It includes water tablets (diuretics) to get rid of excess fluid, angiotensin converting enzyme inhibitors (ACE-i) and beta-blockers. Other drugs may be necessary should symptoms persist on first-line treatment. Please note that ACE-i and beta-blockers have an abundance of evidence supporting their use in DCM and every patient should be on them unless contraindicated or significant side-effects arise.

When medical treatment fails device therapy may be necessary. This includes the insertion of specialised pacemakers under the skin that help the heart beat more efficiently. A small number of patients with dilated cardiomyopathy who do not respond to the above treatments may be referred to a specialist centre for assessment of the potential for cardiac transplantation. Strict criteria apply to the selection of patients in order to assure a successful transplantation.

Read myheart member, Paul Cowling’s story of living with dilated cardiomyopathy here.