Cardiomyopathy is a general term for diseases of the heart muscle, where the walls of the heart chambers have become stretched, thickened or stiff. This affects the heart's ability to pump blood around the body.
Some types of cardiomyopathy are inherited and are seen in children and younger people.
This page explains the main types of cardiomyopathy:
In hypertrophic cardiomyopathy, the heart muscle cells have enlarged and the walls of the heart chambers thicken.
The chambers are reduced in size so they can't hold much blood, and the walls can't relax properly and may stiffen.
How serious is it?
Most people with hypertrophic cardiomyopathy will be able to live a full, normal life. Some people don't even have symptoms and don't need treatment.
But that doesn't mean the condition can't be serious. Hypertrophic cardiomyopathy is the most common cause of sudden unexpected death in childhood and in young athletes.
The main heart chambers can become stiff, leading to back pressure on the smaller collecting chambers. This can sometimes worsen the symptoms of heart failure and lead to abnormal heart rhythms (atrial fibrillation).
Blood flow from the heart may become reduced or restricted (known as obstructive hypertrophic cardiomyopathy).
Also, the mitral heart valve can become leaky, causing blood to leak backwards. Read more about mitral regurgitation.
These heart changes can cause dizziness, chest pain, shortness of breath and temporary loss of consciousness.
You'll also be at greater risk of developing endocarditis (a heart infection).
If you have severe hypertrophic cardiomyopathy, you'll need to see your doctor regularly so your condition can be monitored.
Your doctor will advise about the level and amount of exercise you can do and sensible lifestyle changes to make.
Hypertrophic cardiomyopathy is thought to affect 1 in 500 people in the UK. Most people inherit the disease from their parents.
Restrictive cardiomyopathy is rare and mostly affects older adults. The walls of the main heart chambers become stiffened and rigid and can't relax properly after contracting. This means the heart can't fill up properly with blood.
It results in reduced blood flow from the heart and can lead to symptoms of heart failure, such as breathlessness, tiredness and ankle swelling, as well as heart rhythm problems.
In many cases the cause is unknown, although sometimes it can be inherited.
In arrhythmogenic right ventricular cardiomyopathy (ARVC), the proteins that normally hold the heart muscle cells together are abnormal. Muscle cells can die and the dead muscle tissue is replaced with fatty and fibrous tissue.
The walls of the main heart chambers become thin and stretched, and can't pump blood around the body properly.
People with ARVC typically have heart rhythm problems. Reduced blood flow from the heart can also lead to symptoms of heart failure.
ARVC is an uncommon inherited condition caused by a mutation (change) in one or more genes. It can affect teenagers or young adults and has been the reason for some sudden unexplained deaths in young athletes.
There's increasing evidence that prolonged, strenuous exercise worsens the symptoms of ARVC. It's important that people with or at risk of ARVC have a careful discussion about this with their cardiologist.
Some cases of cardiomyopathy can be diagnosed after various heart scans and tests, such as an echocardiogram.
Cardiomyopathy that runs in the family can be diagnosed after a genetic test. If you've been diagnosed with cardiomyopathy, you may be advised to have a genetic test to identify the mutation (faulty gene) that caused this.
Your relatives can then be tested for the same mutation and, if they have it, their condition can be monitored and managed early.
There's no cure for cardiomyopathy, but the treatments described below are usually effective at controlling symptoms and preventing complications.
Not everyone with cardiomyopathy will need treatment. Some people only have a mild form of the disease that they can control after making a few lifestyle changes.
If the cause of your cardiomyopathy isn't genetic, it should generally help to:
In some people with obstructive hypertrophic cardiomyopathy, the septum (the wall dividing the left and right side of the heart) is thickened and bulges into the main heart chamber. They may need to have either:
an injection of alcohol into their heart – this is to reduce part of the muscle in the septum
a septal myectomy – heart surgery to remove part of the thickened septum (the mitral valve may be repaired at the same time, if necessary)
Those with heart rhythm problems may need to have a pacemaker, or a similar device, implanted to control their abnormal heart rhythm. Read more about having a pacemaker fitted.