Cardiomyopathy

What is cardiomyopathy?

Cardiomyopathy is a disease that changes the structure of the muscle tissue in the heart, or makes it weaker, so it's less able to pump blood efficiently.

Symptoms may appear suddenly with loss of consciousness, or there may be warning signs such as pain in the chest (angina), unexplained breathlessness or a rapid heartbeat (palpitations or arrhythmia).

Cardiomyopathy may be either:

• Primary - no specific cause can be identified
• Secondary - causes can be identified, such as hypertension (high blood pressure), heart valve disease, artery diseases or congenital heart defects, as well as disease affecting organs other than the heart. Alcohol and drug use (both street drugs and medical drugs) can also cause cardiomyopathies

There are three main types of cardiomyopathy or disease of the heart muscle:

• Hypertrophic cardiomyopathy - the most common cause of sudden and unexpected death in people under 30
• Dilated cardiomyopathy – the most common type of cardiomyopathy
• Restrictive cardiomyopathy – the least common type, usually seen in the elderly

Symptoms of cardiomyopathy

The symptoms may depend on the type of cardiomyopathy. It may present at any age, causing:

• Breathlessness on exercise
• Chest pain
• Palpitations
• Dizziness
• Collapse with loss of consciousness
• Tiredness and general lack of energy
• Blood clot formation with pulmonary emboli or stroke
• In the most severe cases, sudden death

Hypertrophic cardiomyopathy

The heart muscle thickens greatly (often asymmetrically) and the muscle cells may become disorganised (which can interfere with the passage of electrical signals through the muscle), without any obvious trigger. In most cases the disease is hereditary, resulting from a gene abnormality. The disease is thought to affect at least 125,000 people in the UK.

In one form of hypertrophic cardiomyopathy (hypertrophic obstructive cardiomyopathy or HOCM) the muscle mass of the left ventricle and the wall that divides it from the right side of the heart (the septum) becomes larger than it should be. This leads to narrowing of the passage through the heart and obstruction of the blood flow out of the heart.

In addition the muscle is stiff and has difficulty relaxing, increasing the amount of pressure required to expand the heart while blood flows in. This reduces the blood holding capacity of the heart.

The altered structure may distort the mitral valve between the chambers of the heart (the left atrium and left ventricle) which may then leak. It's also known as asymmetric septal hypertrophy (ASH) or idiopathic hypertrophic subaortic stenosis (IHSS).

The condition can be present in the foetus and cause stillbirth, or may develop in infancy. But, more usually, it develops during childhood or early adulthood.

In another form of the disease, non-obstructive hypertrophic cardiomyopathy, the enlarged muscle doesn't obstruct the blood flow.

The symptoms of hypertrophic cardiomyopathy include shortness of breath on exertion, dizziness, fainting and angina pectoris (angina is chest pain or discomfort caused by reduced blood supply to the heart muscle.) The obstruction to blood flow from the left ventricle increases the ventricle's work, and a heart murmur may be heard. Some people have cardiac arrhythmias. These are abnormal heart rhythms that in some cases can lead to sudden collapse and death.

Treatment, which includes anti-arrhythmia drugs, aims to control symptoms and prevent complications such as sudden collapse. Surgery may be necessary to remove some of the muscle or repair the mitral valve. A special device called an implanted cardioverter defibrillator (ICD) may need to be put into the heart to deliver and electric shock which will get the heart back into a normal heart rhythm whenever arrhythmias occur, in order to prevent sudden death.

Because there may be a genetic cause, other members of the family should be screened to check for the faulty gene.

Dilated cardiomyopathy

Dilated, or congestive, cardiomyopathy is more common and occurs due to enlarging and stretching of the heart cavity, weakening the heart so it doesn't pump normally.

The heart muscle becomes weak and too flexible, preventing it pumping blood efficiently around the body. Because the heart is stretched or dilated, the valves may not close very well and may become leaky. Breathlessness results as fluid builds up in the lungs, congesting them. This is called left heart failure. There may also be right heart failure, where fluid accumulates in the tissues and organs of the body, usually the legs and ankles, and the liver and abdomen. Disruption of the heart's electrical rhythm also often occurs.

The cause of the condition is unknown in many cases, but it can be caused by infection with a virus, auto-immune diseases such as rheumatoid arthritis, excessive consumption of alcohol or, rarely, as a result of pregnancy - peri-partum cardiomyopathy.

Shortness of breath, palpitations, tiredness, swollen ankles and angina are common symptoms. Blood clots often form because the blood is flowing more slowly through the heart. These clots may break free and move to the lungs causing pulmonary emboli or to the brain causing a stroke.

Treatment may include anti-clotting drugs to prevent emboli, and medication to prevent arrhythmias and help the heart to work more efficiently. Any underlying cause should be identified and treated too. In severe cases a heart transplant may be necessary.

Restrictive cardiomyopathy

Restrictive cardiomyopathy is the least common form and occurs when the heart muscle of the ventricles, or myocardium, is excessively rigid, impairing the filling of the ventricles with blood between heartbeats. Tiredness, shortness of breath and swollen feet and hands typically occur.

Arrhythmogenic right ventricular cardiomyopathy

In another form of cardiomyopathy, the heart muscle is replaced by fibrous scar and fatty tissue. This may occur after a heart attack, where muscle is damaged - the right ventricle tends to be most affected. The right side of the heart may first thicken and later dilate - become thinner. It may lead to disordered electrical activity, and in some cases problems with the heart's pumping action.

Advice and support

Cardiomyopathy Association

• Tel: 0800 018 1024
• Email: info@cardiomyopathy.org
• Website: www.cardiomyopathy.org