Diagnosis and symptoms

How is cardiomyopathy diagnosed?

Some people may go to their GP because they are experiencing symptoms that they are worried about. They may have been taken to hospital because they have unexplained symptoms such as chest pain or passing out. Perhaps someone in their family has a heart condition and they are concerned that they may have it too. 

If it is suspected that your child may have cardiomyopathy, you will usually be referred to a specialist: a paediatrician or paediatric cardiologist. The specialist will ask questions about symptoms, look at
their medical and family history, and ask for several tests to be done, to see if they have cardiomyopathy.

What the specialist will ask about

Symptoms – the specialist will ask about any symptoms your child has, such as shortness of breath, feeling dizzy or passing out, or chest pain. They will ask about when the symptoms happen, and whether anything makes symptoms worse (such as exercise). They might also do a physical examination (such as listening to the chest and heart). 

Medical history – the specialist will ask about any conditions or illnesses that your child has had that could cause cardiomyopathy (or could explain any other cause of the symptoms).

Family history – the specialist will ask whether there is a history of cardiomyopathy in your family (as cardiomyopathy can run in families).

Usual tests for cardiomyopathy

ECG (electrocardiogram) – this looks at the electrical activity of the heart and whether arrhythmias (abnormal heart rhythms) are happening. An ECG might be done during exercise (if exercise usually
brings on the symptoms), or a portable ‘holter monitor’ might record the heart rhythm over a couple of days.

Echo (echocardiogram) – this is a type of ultrasound scan, which uses sound waves to create echoes when they hit different parts of the body. These echoes are translated into 2- and 3- dimensional images. This test looks at the structure of the heart, and are used to see if the heart is enlarged or if there is any thickening of the heart muscle. The images are moving, so can also look at how the heart is working. A Doppler echo looks at the speed and flow of blood through the heart, which also helps to check how the heart is working.

An echo of the heart

MRI (magnetic resonance imaging) scan – this is a type of scan which gives high quality images and is used to look at the structure of the heart and how blood flows through it. It can also be used to measure any areas of thickened muscle.

MRI machine. Copyright Epilepsy Society.

There may be other tests that are suggested (depending on the results of the tests above), and will be used to help diagnose the cardiomyopathy or look for other causes of the symptoms.

“Any question is not a silly question, but something that you are not sure of and you mustn’t be afraid to ask.”

What are the symptoms of cardiomyopathy?

The role of the heart is to pump blood around the body, carrying oxygen and nutrients to ‘power’ the cells and organs. Cardiomyopathy affects how effectively the heart works, and so when the heart isn’t
working as efficiently as it should, cells and organs don’t get enough oxygen and nutrients. Symptoms of cardiomyopathy can be caused by:

  • disruption in the electrical signalling in the heart;
  • reduced or disrupted flow of blood around the heart;
  • poor supply of oxygen and nutrients to the body; and
  • poor removal of waste products from the body.

There are many symptoms of cardiomyopathy. Not everyone will have symptoms, but some will have symptoms (depending on how well their heart is working). Symptoms can include the following.

  • Tiredness – due to reduced circulation and oxygen levels in the blood, which means that the cells and organs aren’t receiving enough oxygen and nutrients to ‘power’ the body.
  • Breathlessness – due to a build up of fluid (called oedema) in the lungs which makes it harder to breathe.
  • Swelling in the abdomen and ankles – due to a build up of fluid. 
  • Palpitations (feeling your heart beating too fast, too hard or like it is ‘fluttering’) – caused by abnormal heart rhythms (‘arrhythmias’) where the heart is beating too fast or erratically. This can be caused by a problem with the electrical messages which control the heart’s normal beating rhythm, causing the messages to be disrupted.
  • Chest pain or a feeling of ‘tightness’ in the chest – although the cause is not always clear, it may be due to reduced blood flow out of the heart. It may happen when the heart is under increased pressure (such as during exercise), as the heart needs to work harder to supply the body with oxygen.
  • Dizziness or fainting – caused by reduced oxygen levels or blood flow to the brain. This can cause light-headedness or dizziness and, in some cases, loss of consciousness or fainting.

Cardiomyopathy and heart failure

Heart failure is when the heart is not working effectively and it ‘fails’ to pump enough blood, at the right pressure, to meet the body’s needs. (It doesn’t mean that the heart is not working at all, just that it is not working well enough.) It describes a collection of symptoms caused by a heart that is struggling to work effectively. These symptoms include weight gain (due to fluid retention), a cough, shortness of breath, oedema, palpitations, dizziness and tiredness.

Heart failure is not always caused by cardiomyopathy (there are other causes) and not everyone with cardiomyopathy has heart failure.

How severe someone’s heart failure is may be measured by the New York Heart Association (NYHA) classification system, which measures how much the symptoms limit the person’s activity. You might come across these terms if your child has heart failure.

  • Class I (unaffected): activities are unlimited, and ordinary activity doesn’t cause symptoms.
  • Class II (mildly affected): activity is limited a little. Activities such as walking up several flights of stairs causes some symptoms such as tiredness, palpitations and breathlessness.
  • Class Ill (moderately affected): activity is more limited than class ll.  Symptoms happen at activities such as walking on a flat surface.
  • Class IV (severely affected): activity is very limited. Symptoms happen with all activity, and the person is breathless even when resting.

Treatments for heart failure support the heart to work better, such as:

  • a healthy diet and reduced salt intake to help keep a healthy weight;
  • exercise to help with overall fitness and help the heart to function;
  • limiting alcohol and caffeine, and not smoking; and
  • medication such as ACE inhibitors, beta-blockers and diuretics.

Other treatments depend on the cause of heart failure. For example, if there is a problem with a valve in the heart it might need to be repaired or replaced.

Are there any complications of cardiomyopathy?

Sometimes, because the heart is working less well than normal, there can be complications that develop from cardiomyopathy. Part of treating cardiomyopathy is to reduce the chance of complications, but there are also ways to treat any complications that happen.


Arrhythmias are abnormal heart rhythms that cause the heart to beat too fast, too slow or in an erratic way. Some arrhythmias are temporary and don’t cause lasting problems. However, some are
more dangerous and need to be treated urgently (as they can cause blood clots or a cardiac arrest). They can be treated with medication (anti-arrhythmic drugs) or devices that control the heart rhythm such as pacemakers or ICDs.

Blood clots

Blood clots can form in the heart when blood doesn’t circulate well. For example, in the arrhythmia called ‘atrial fibrillation’ the heart muscle doesn’t contract properly, making blood flow around the atria turbulent which can cause blood clots to form. Blood clots travelling in the blood stream can cause strokes, so medications may be used to help the heart to contract in a normal rhythm (anti-arrhythmic drugs), and to thin the blood to reduce the risk of clots forming (anticoagulants).

Cardiac arrest

A cardiac arrest is when the heart suddenly stops pumping blood around the body. This can happen due to dangerous arrhythmias such as ventricular fibrillation (which makes the ventricles ‘quiver’ rather than contracting normally, and so blood doesn’t flow out of the heart effectively). A cardiac arrest will cause the person to collapse and stop breathing, unless a defibrillator is used to shock the heart back into a normal rhythm. This is sometimes referred to as sudden cardiac death. People who are at risk of cardiac arrest may have an ICD (implanted defibrillator) which monitors the heart for any dangerous arrhythmias and shocks the heart if one is detected.

©Cardiomyopathy UK. May 2017.