Your guide to dilated cardiomyopathy: causes, symptoms and treatments
Written by:Dilated cardiomyopathy (DCM) is a condition in which the heart chambers become enlarged, stopping your heart from pumping blood efficiently around the body. It usually occurs in adults between the ages of 20 and 60.
Studies suggest that around 1 in 2,500 people in the UK have dilated cardiomyopathy; however, this number could be higher, as many people living with the disease may not realise they have it.
In this article, Dr Resham Baruah, a top consultant cardiologist at the Chelsea and Westminster Hospital in London, walks us through the causes of DCM, the symptoms and the treatment available.
What is dilated cardiomyopathy?
Dilated cardiomyopathy (DCM) describes an enlarged heart. It typically begins in the left ventricle (the main pumping chamber) which stretches and thins (dilates) and causes a reduced force of contraction or pumping. This means your heart can't pump blood around your body efficiently.
The same process can also occur after a person has had a heart attack. However, when doctors talk about DCM, they generally mean an enlargement of the heart with a reduction in its function, which isn't due to disease of the arteries supplying the heart but rather a problem with the heart muscle itself.
Cardiologists sometimes talk about “ejection fraction”, which is the percentage of blood being pumped out with each heartbeat. It is important to know that this is not normally 100 per cent, but usually somewhere over 50 per cent for most people. It can vary by gender, age, and size as well as a myriad of other factors.
How is dilated cardiomyopathy diagnosed?
One of the first investigations we perform in patients with suspected DCM is an echocardiogram (an ultrasound of the heart), and very often we go on to do a cardiac MRI scan. Both modalities will give us an “ejection fraction” but the number we get often differs between the echocardiogram and the MRI scan due to differences in the techniques.
How an individual feels is usually a much better marker of how their disease will progress than using the ejection fraction. These numbers alone should be considered with caution.
What are the symptoms of the condition?
Often symptoms creep up on people. Everyone experiences things differently but it’s most common that people feel extremely tired and their ability to exercise is reduced because of their breathlessness.
Some people feel their heart racing (palpitations), others feel their chest is tighter and some notice abdominal pain and swelling and swelling of the ankles or legs. It is also common for people to feel quite depressed and anxious, and some people describe their shortness of breath as similar to a panic attack.
If fluid starts accumulating within the lungs due to the heart’s inefficiency, people find they are more breathless if they lie flat. In the extreme, some people end up sleeping in chairs and their sleep is disturbed as they wake from sleep breathless. This is obviously a very worrying sign and anyone who feels this way should seek urgent medical attention.
What causes dilated cardiomyopathy?
Around a third of patients with DCM are thought to have a genetic cause. Other causes include:
- Viral infections – some relatively common viruses are known to attack heart muscle cells, damaging them and eventually causing DCM. We didn’t see this so much at the beginning of COVID-19; however, we do see stress cardiomyopathy develop with severe COVID-19 infection.
- Uncontrolled high blood pressure.
- Problems with your heart valves.
- Excessive alcohol or drugs, such as cocaine.
- Pregnancy - this is called peripartum cardiomyopathy and usually manifests in women within three months of delivery.
- Chemotherapy, such as anthracycline therapy.
- Heart rhythm problems, including very fast heart rates, though unfortunately because DCM puts pressure on the heart overall, patients with DCM can also develop heart rhythm problems as a result of their DCM.
Most genetic DCM cases are inherited in an autosomal dominant pattern whereby the risk of offspring inheriting the gene from a parent is 50 per cent. However, some muscle disorders which can also affect the heart muscle, such as Duchenne muscular dystrophy or Becker’s muscular dystrophy, are X-linked with males inheriting the mutation from their mothers.
Some mutations are very common and probably require other factors such as high alcohol intake or chemotherapy to lead to DCM. Given the genetic basis, we often not only screen patients but also their families for DCM.
How is dilated cardiomyopathy treated?
The mainstay of treatment is medication therapy no matter what the cause.
Simple diuretics such as bumetanide and furosemide can treat the symptoms but do not improve the underlying function of the heart.
Most people with advanced DCM, which is determined by EF< 35% by echocardiogram, will need four different classes of medication to try and get the pumping function to improve.
These four different classes of medication are:
- ACE inhibitors (the names of these tend to end in -pril and for many years they were the most powerful drugs we had) OR angiotensin receptor antagonists (these tend to end -artan) OR ARNI Entresto (also called sacubitril valsartan)
- Beta-blockers e.g. bisoprolol or nebivolol
- Mineralocorticoid receptor antagonists e.g. spironolactone or eplerenone
- Sodium-glucose cotransporter 2 inhibitors e.g. dapagliflozin
These tablets, when taken in combination, have been demonstrated in trials to make people live longer and feel better. However, they usually need to be taken for life to maintain this, even if there is an improvement in the pumping function.
Patients who do not have a rapid improvement in function may require a special pacemaker if there is evidence of discoordinate pumping of the heart. This is called a biventricular pacemaker or cardiac resynchronisation therapy (CRT). The aim of this pacemaker is that it coordinates both sides of the left ventricle so that it beats more efficiently. It has been shown to make people live longer and feel better.
Some patients with DCM are unfortunately at risk of life-threatening arrhythmias. In these cases, it is possible to implant an implantable cardioverter-defibrillator, which is a simpler pacemaker that can detect these life-threatening arrhythmias and deliver an electric shock to reset the heart if required. On their own, these may be life-prolonging and for appropriate patients, it can be combined with the CRT and therefore can improve symptoms too, as well as be potentially be life-saving.
Experimental treatments such as mitral and tricuspid valve clips are being developed all the time and may be of benefit in some patients.
More advanced therapies for some people include mechanical heart support devices or ventricular assist devices (VADs) which may be able to support the minority of patients who require heart transplantation.
Diet, exercise and lifestyle are important for all patients with DCM.
Are there any advancements in dilated cardiomyopathy treatments?
Experimental treatments such as mitral valve clips are being developed all the time and could be of benefit to some patients.
More advanced therapies for some people include mechanical heart support devices or ventricular assist devices (VADs) which may be able to support the minority of patients who require heart transplantation.
What are the possible complications if left untreated?
Left completely untreated, DCM is a chronic progressive condition that leads to heart failure with fluid accumulation in the lungs and body and a reduction in blood flow to vital organs such as the kidneys. Patients with untreated DCM are not only at risk of heart failure but also life-threatening arrhythmias which could cause a cardiac arrest.
Can someone live a normal life on medication for dilated cardiomyopathy?
Absolutely! Traditionally, about a third of patients were thought to see an improvement with the tablets but given lots of recent progress in the field, newer data suggest up to half of DCM patients may see an improvement in their heart's pumping function with some seeing a total resolution of their symptoms.
If you are worried about your heart health and would like to see an expert cardiologist, head to Dr Resham Baruah’s Top Doctors profile and book an appointment to see her.
