Stanford Center for Inherited Cardiovascular Disease

Familial Dilated Cardiomyopathy In Depth

Dilated cardiomyopathy, or enlarged heart with large pumping chambers due to heart muscle disease (cardiomyopathy), has many causes. In as many as 40% of all patients with dilated cardiomyopathy, a family member who also has cardiomyopathy is identified. These families are often found to have a genetic cause of disease.

One disease, many causes

In some, dilated cardiomyopathy may occur sporadically in only one family member who develops the disease, but the cause of the disease is genetic in nature. In other families, dilated cardiomyopathy is due to causes, such as:

Symptoms in Dilated Cardiomyopathy

Patients with dilated cardiomyopathy may have no, subtle, or overt symptoms. Patients in the same family may have different symptoms, even if they share a common genetic cause of the disease. Common symptoms in familial dilated cardiomyopathy may include shortness of breath with exertion, fatigue, abdominal swelling, lower leg swelling, nausea, chest pain, chest pressure, palpitations, skipped beats, dizziness and/or fainting. Additional symptoms can be unintentional weight gain, difficulty sleeping, waking abruptly due to feeling short of breath, or intolerance of sleeping in a flat bed, change in appetite and/or increase in symptoms after eating. In some cases, patients with dilated cardiomyopathy can be completely without symptoms (asymptomatic), and have normal tolerance for exercise and activities. In rare cases, the first symptom of dilated cardiomyopathy can be sudden death.

Given that symptoms are a poor guide to the presence or absence of disease in family members, and the fact that early treatment can lead to significant improvement in quality of life and life expectancy, our team stresses the importance of screening potentially at-risk family members.

Familial Dilated Cardiomyopathy Changes in the Heart

Familial dilated cardiomyopathy is most often due to underlying genetic abnormalities in the muscle cells of the heart (cardiomyocytes).

Isolated cardiomyocyte

These heart muscle cells, which are the fundamental units of the heart, contract (shorten) every time your heart beats – over 3 billion times over the average American human lifetime. Even small changes in how these cells function, over time, can lead to weakness of the heart and heart failure. These changes also lead to abnormalities in the structure of the heart, as the heart muscle cells are replaced by fibrous tissue or fatty tissue. Hearts that have a lot of fibrous or fatty tissue do not contract as well as hearts with mostly muscle cells.

Over time, these hearts weaken and dilate. These dilated hearts are also more prone to bad heart rhythms (arrhythmias) that can lead to symptoms or early sudden death.

Genetics of Familial Dilated Cardiomyopathy

Familial dilated cardiomyopathy is caused by a mutation in one of many genes. Genes, which are present in every cell of your body, encode for RNA and protein, which are the fundamental building blocks of the cell. A single mutation in one gene leads to changes in the code that makes a protein. This in turn may affect the function of the cells in which that protein is found. There are many genes, which when mutated, may cause dilated cardiomyopathy. A list of these genes may be found here. Most of these gene mutations are inherited in a dominant fashion, meaning that family members sharing just one copy of the mutated gene are at risk for developing overt signs of disease. For other genes, inherited in a recessive fashion, two mutations are required to develop disease. Other forms of inheritance are also seen in families presenting with dilated cardiomyopathy. More about cardiovascular genetics.

Treatment Options

Patients with familial dilated cardiomyopathy are treated with the same medications that are used to treat other forms of dilated cardiomyopathy and heart failure. Treatment of patients with dilated cardiomyopathy is personalized and depends on both symptoms and clinical findings. Clinical testing includes echocardiography (ultrasound pictures of the heart), ambulatory telemetry (monitoring the rhythms of the heart, typically at home over 24 hours or more), cardiopulmonary exercise testing (treadmill or bike test to measure exercise capacity), blood tests, and other tests. Patients who are asymptomatic may take medications called ACE inhibitors and/or beta-blockers to prevent or halt progression of disease. Patients who are symptomatic are treated with a combination of medications and/or procedures to reduce symptoms and improve life expectancy. Additional treatment options including pacemakers, implantable cardioverter defibrillators (ICDs), ventricular assist devices (VADs) and heart transplantation are considered in certain cases (needs hyperlinks to EP and CTS). Family members who are at risk for disease may be treated or watched closely over time for manifestations of disease.

Screening of Family Members

All first-degree family members (sons, daughters, brothers, sisters, parents) of a patient with familial dilated cardiomyopathy should undergo screening for dilated cardiomyopathy with echocardiography and electrocardiogram. Other family members may undergo screening if their first-degree relatives are found to have disease or have high risk occupations or activities such as competitive sports. If genetic testing is performed and a mutation is found, all family members who have the mutation are recommended to undergo a comprehensive clinical assessment. All individuals with symptoms of dilated cardiomyopathy should undergo clinical evaluation.

Genetic Testing in Familial Dilated Cardiomyopathy

Dilated cardiomyopathy is often due to an underlying genetic change. This has important implications for a patient’s siblings, children, and parents. Additionally, in some cases, other organ systems may be affected due to the same genetic change. At Stanford’s Center for Inherited Cardiovascular Disease, patients with dilated cardiomyopathy are evaluated carefully for evidence of a familial component of disease. Currently there is no available single genetic test that allows comprehensive testing of all genes that have been shown to cause dilated cardiomyopathy. Based on the clinical features of a family’s or patient’s presentation of disease, our team will determine which genetic test, if any, is most appropriate. If a genetic test finds a mutation that is likely to cause disease, other members of your family can undergo greatly simplified testing for the initial mutation found. Our team of experts will explain to you and your family the full benefits and risks of genetic testing. Knowing the causative mutation allows for personalized screening in parents, siblings and other family members, early identification, and preventative treatment to halt or reverse the progression of disease. Additionally, in certain cases, treatments and risks of inheritance differ depending on the findings of genetic testing.

Contact Us

Families with dilated cardiomyopathy have varied experiences with heart disease. The Stanford Center for Inherited Cardiovascular Disease team delivers personalized care to each individual with dilated cardiomyopathy, their family members, and individuals who carry genetic mutations but do not yet manifest disease. Email or (650) 725-6186 to arrange for a consultation.

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