Cardiomyopathy is a general term for diseases of the heart muscle. It is when the walls of the heart chambers have become stretched, thickened or stiff, affecting 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 four main types of cardiomyopathy:
arrhythmogenic right ventricular cardiomyopathy
It then explains genetic testing for cardiomyopathy and the available treatments.
What is dilated cardiomyopathy?
In dilated cardiomyopathy the muscle walls of the heart have become stretched and thin, so they cannot contract (squeeze) properly to pump blood around the body.
How serious is it?
If you have dilated cardiomyopathy, you're at greater risk of heart failure, where the heart fails to pump enough blood around the body at the right pressure.
Heart failure typically causes shortness of breath, extreme tiredness and ankle swelling. Learn more about the symptoms of heart failure.
There's also a risk of heart valve problems, an irregular heartbeat and blood clots. You will need to have regular appointments with your GP so the disease can be monitored.
Dilated cardiomyopathy can affect both children and adults.
The heart muscle can become stretched if you have an unhealthy lifestyle or an underlying medical condition, or both. The following can all play a role in the disease:
uncontrolled high blood pressure
an unhealthy lifestyle – such as a lack of vitamins and minerals in the diet, heavy drinking and recreational drug use
a viral infection that causes inflammation of the heart muscle
a heart valve problem
a disease of the body tissues or vessels – such as Wegener's granulomatosis, sarcoidosis, amyloidosis, lupus, polyarteritis nodosa, vasculitis or muscular dystrophy
inheriting a mutated (changed) gene that makes you more vulnerable to the disease
pregnancy – cardiomyopathy can sometimes develop as a complication of pregnancy
But for many people, the cause is unknown.
Read the British Heart Foundation's detailed booklet on dilated cardiomyopathy.
What is hypertrophic 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 cannot hold much blood, and the walls cannot 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 cannot 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.
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 will have inherited the disease from their parents.
What is restrictive cardiomyopathy?
Restrictive cardiomyopathy is rare and mostly affects older adults. The walls of the main heart chambers become stiffened and rigid and cannot relax properly after contracting. This means the heart cannot 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.
What is arrhythmogenic right ventricular cardiomyopathy?
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 cannot 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.
How is cardiomyopathy diagnosed?
Some cases of cardiomyopathy can be diagnosed after various heart scans and tests, such as an electrocardiogram (ECG) and 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.
How is cardiomyopathy treated?
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 for your cardiomyopathy isn't genetic, it should generally help to:
follow a healthy diet and take gentle exercise
quit smoking (if you smoke)
lose weight (if you're overweight)
avoid or reduce your intake of alcohol
get plenty of sleep
make sure any underlying condition, such as diabetes, is well controlled
Medication may be needed to control blood pressure, correct an abnormal heart rhythm, remove excess fluid or prevent blood clots.
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.
As a last resort, a heart transplant may be necessary.
Hypertrophic cardiomyopathy (L); dilated cardiomyopathy (R)
'Broken heart syndrome'
Some people who sustain significant emotional or physical stress, such as bereavement or major surgery, go on to experience a temporary heart problem.
The heart muscle becomes suddenly weakened or "stunned", causing the left ventricle (one of the heart's main chambers) to change shape. The cause of this may be a surge of hormones, particularly adrenaline, during this period of stress.
The main symptoms are chest pain and breathlessness, similar to those of a heart attack – always call 999 if you or someone else experiences these.
The condition – known medically as Takotsubo cardiomyopathy, or acute stress cardiomyopathy – is temporary and reversible. It's unusual for it to happen again.
Source: British Heart Foundation