Familial Dilated Cardiomyopathy (FDC)

Dilated cardiomyopathy affects many people. In some cases a cause such as coronary artery disease, viruses, alcohol and thyroid disease can be found. However in up to 50% of cases no cause can be identified. Familial dilated cardiomyopathy (FDC) accounts for approximately 20-50% of these cases and is caused by an inherited gene alteration (or “mutation”), which makes investigation of the family very important.

Dilated cardiomyopathy is characterised by an enlargement of the left ventricle (the main pumping chamber of the heart) due to the thinning and ballooning out of the ventricular muscle wall. This affects the heart’s ability to effectively pump out blood (shown below). In severe cases, this can lead to heart failure, where the pumping function of the heart is very poor and leads to symptoms such as shortness of breath, swelling of the ankles and legs, and fatigue. In some cases, dilated cardiomyopathy may affect the electrical system of the heart, leading to rhythm problems that may require implantation of a pacemaker. Rarely, dilated cardiomyopathy can cause sudden death.

We know that there is a wide range in the severity of symptoms seen even within a family. One family member may suffer severe heart failure or even sudden death while someone else may have only very mild disease causing minimal problems. For this reason, we advise anyone with a family history of FDC to see a cardiologist on a regular basis. Early detection is important as disease progression can then be carefully monitored and treated to hopefully prevent future complications.

How it is inherited

In many cases FDC is inherited as an autosomal dominant disease (see Genetic Inheritance and Testing for more information). However, some families have disease that is inherited as an x-linked or recessive trait, meaning one gender may be more prone to developing disease.

Genetic testing

Genetic testing for FDC is not as straightforward as other inherited heart diseases. So far over 30 genes have been identified to cause disease. As searching through even one gene is an expensive and time consuming task, genetic testing is not yet a routine option in these FDC families. Further research will hopefully improve this in the future.

If you would like to find out more about how genetic testing may be useful in your family, please contact a clinic coordinator at your nearest Cardiac Genetic Service .

Common Treatments

Your cardiologist will decide what medications or treatments you may require. Many patients will not need any medications, particularly if there are no symptoms. Some common medications are:
Beta-blockers: these are very commonly used in the general population to treat high blood pressure. They are used in FDC patients to slow the heart rate and reduce the effect of sudden exertion or excitement on the heart. As beta-blockers make the heart beat slower, it allows blood to completely fill the chambers before it is pumped out, leading to improved heart function. Examples include Metoprolol, Atenolol, and Nadolol.
Heart failure medications include Angiotensin Converting Enzyme Inhibitors (ACE Inhibitors), Angiotensin II inhibitors, Digoxin and Diuretics (fluid tablets). These work in many different ways but basically assist the heart to pump blood more efficiently and reduce fluid retention.

Advice to family members

Direct family members of someone who has been diagnosed with FDC should have their hearts checked by a cardiologist , which is known as Clinical Screening . Direct family members include children, brothers and sisters, and parents. As FDC is an inherited heart condition, these family members are generally at a 1 in 2 (50%) risk of also carrying the gene and are termed at-risk relatives.

We rely on this information being passed on within a family. Therefore we ask you to encourage any at-risk relatives to arrange an appointment with a cardiologist. We know there is huge variation in the range of symptoms seen even within a family. For example, some family members may have minimal symptoms while others have the most serious outcomes of heart failure and sudden death. So even though an at-risk relative may feel healthy and well, it is possible they could have mild disease. If this is the case, they may not necessarily need to start any treatments but they would then know that their children are at-risk and could arrange appropriate medical screening for them. Please talk to the coordinator of a Cardiac Genetic Service near you for more information or to organise a ‘heart check’.

National Genetic Heart Disease Registry

FDC is one of the diseases being investigated by the Registry. We aim to enrol every family in Australia with FDC. Find out more about the Registry or enrol yourself or your family by emailing the Registry Coordinator.