Cardiomyopathy means heart muscle disease (‘cardio’ = heart, ‘myo’ = muscle, and ‘pathy’ = disease).  Many forms of cardiomyopathy exist, but by far the most common category is dilated (= enlarged) cardiomyopathy.

The heart is made out of muscle and works as a blood pump, providing blood to the body. The heart enlargement (dilation) occurs because the heart muscle becomes weakened. When the heart enlarges as a result of muscle weakening, the pumping action of the heart becomes weaker also. As a result, less blood than normal may be pumped to the body, especially during vigorous activity.

DCM is usually diagnosed in adulthood, during the fourth to sixth decade (ages 40-60), but it has been found in infants and the elderly.  Some cases present during or soon after pregnancy. This is known as peripartum cardiomyopathy (PPCM). DCM can also be asymptomatic for many years.

The symptoms of DCM include heart failure, heart beat abnormalities (arrhythmia) and sudden cardiac death. In some individuals, arrhythmias are the first sign. DCM can also be asymptomatic for many years.

Heart failure (also called congestive heart failure), is a common symptom of DCM. When heart failure is present, the heart cannot pump enough blood to the body. Heart failure does not mean that the heart “stops suddenly” as the words imply. Instead, heart failure leads to shortness of breath with activity, fluid collection (edema) in the feet and legs, difficulty sleeping flat in bed (needing to prop oneself up on several pillows), and at times awakening in the middle of the night short of breath and needing to sit up to the edge of the bed for several minutes to catch one’s breath. DCM does not always lead to heart failure, although in their late stages, most people with DCM begin to have some symptoms of heart failure.

In DCM, irregular and/or fast heart rhythms (arrhythmia) can also occur. Some such rhythms cause palpitations. Palpitations are the sense of one’s heart “skipping a beat,” or beating too fast, or beating very hard, and can last from seconds to minutes, and even, occasionally, hours. With rapid heart rates, individuals may feel dizzy or lightheaded, or experience shortness of breath with minimal activity.

A more severe symptom of arrhythmia is called syncope. Syncope is the medical term for complete loss of consciousness. Other common terms used for syncope include “a blackout spell” or “a fainting spell.” Because syncope may be caused by more dangerous arrhythmias, it always requires immediate medical attention.

Sudden death, or sudden cardiac death, is the term used to describe syncope resulting from an arrhythmia that is accompanied by full cardiac arrest (loss of heart rate, blood pressure, and breathing). If someone suffers an episode of sudden cardiac death, the patient must undergo successful cardiopulmonary resuscitation to survive. Although, at times, it is possible that the lethal arrhythmia may stop by itself and the patient may regain normal a normal heart rate, blood pressure and breathing. If a patient survives an episode of sudden cardiac death, emergency medical treatment is needed to evaluate, treat and prevent future episodes from occurring.

About 50-60% of all dilated cardiomyopathy (DCM) in the US results from heart muscle damage caused by myocardial infarction (heart attack) from coronary heart disease. (We do not study this type of DCM). Coronary heart disease is a condition in which the blood vessels that provide blood supply to the heart (coronary arteries) become narrowed with cholesterol plaque. A heart attack occurs when a cholesterol plaque ruptures in a coronary artery and blocks the flow of blood and oxygen to the heart muscle.  The lack of oxygen (ischemia) results in the death of part of the heart muscle. When a large part of the heart muscle dies from a heart attack, the remaining heart muscle weakens (cardiomyopathy) and the heart may become enlarged over time. This type of cardiomyopathy is called ischemic dilated cardiomyopathy.

The next most common type of DCM (40-50%) is called idiopathic dilated cardiomyopathy, or IDC. Idiopathic means “cause is unknown.” Thus, for a patient to have a formal diagnosis of IDC, coronary heart disease should have been excluded.  Other potential, less common causes of dilated cardiomyopathy should also be excluded. These include certain chemotherapy drugs used to treat cancers, problems with heart valves, congenital heart disease, insufficient thyroid hormone levels or iron overload in the heart muscle.

Individuals with DCM of unknown cause (IDC) do not present a different set of symptoms than individuals with DCM from other causes. They do not present at a different age than individuals with DCM from other causes either. While the symptoms and age of onset in IDC is not different from DCM, it is now known that genetics plays a role in IDC.

IDC can run in families. When IDC is present in two or more family members, the term FDC is used. Until the early 1990’s, it was thought only about 1-2% of cases ran in families. In 1992, however, a U.S. study demonstrated that 20% of patients with IDC had affected first-degree family members (parents, siblings, or children). Data published in 1998 from two European studies reported that 35-50% of cases were familial.

Part of the reason is that family members may have few or no symptoms, or they may have very different symptoms from one another. They may also develop these symptoms at different ages. In some cases affected individuals die suddenly, and in years past this may have been attributed to a “heart attack” (coronary artery disease, ischemic DCM) rather than to IDC.

Sporadic DCM refers to idiopathic DCM occurring in only one family member, after cardiovascular screening has ruled out DCM in first degree relatives (parents, children, siblings). The heart changes associated with DCM can be present in the absence of symptoms. Therefore, if cardiac screening has not been performed in first degree relatives, some individuals may be inaccurately described as having no family history of DCM. Therefore, in the absence of cardiac screening information, a more appropriate term to refer to individuals with no reported family history is simplex DCM or ‘apparently sporadic’ DCM.

 So far all research on the genetic basis of DCM has focused on individuals with idiopathic DCM and their families, primarily familial cases. Familial DCM  has been shown to result from changes (mutations) in the genetic code of several genes whose role is key for normal heart muscle function. In most cases (90% of the time), FDC appears to be inherited as an autosomal dominant trait. Autosomal dominant means that every child of an individual who carries the mutation has a 50% chance of inheriting the mutation, and this mutation is sufficient to cause disease. However, not all individuals who carry a mutation will have signs or symptoms of the disease. This is known as ‘reduced penetrance.’ These “unaffected” carriers still have a 50/50 chance of passing on the altered gene to their offspring.

Our recent data suggests that apparently sporadic/simplex DCM (idiopathic DCM found in only one person in a family), also has a genetic basis. We propose that IDC, whether familial or sporadic, results from different degrees of genetic influence.

It is also possible that genetic factors play a role in DCM caused by coronary artery disease, infections or drug exposures.

No, the symptoms and presentation can vary considerably, even among members of the same family who have the same gene mutation. This is known as ‘variable expressivity.’ For example, an affected person with the gene mutation may have DCM but only have minor arrhythmia symptoms. Another gene carrier in the same family might have a sudden, severe onset at a young age, with cardiopulmonary arrest, or may require heart transplant.

Unfortunately, right now there is no way of knowing how, when or with which symptoms this condition will present, or begin, in a given family member. Therefore, all first degree relatives (parents, children, siblings) of individuals with IDC should be screened. See your doctor if you are concerned that you are experiencing any of the symptoms of cardiomyopathy or heart failure that have been mentioned here.

 The clinical features of IDC from different genes in most cases have considerable overlap with one another, even though approximately 40 different genes have been suggested to cause genetic DCM. One exception is the lamin A/C (LMNA) gene, which may cause from 5-10% of DCM cases. Lamin A/C cardiomyopathy commonly presents with prominent conduction system disease (disorders of the heart’s electrical conduction system which causes a variety of arrhythmias), sometimes prior to the onset of DCM and heart failure.

Evidence from our research suggests that IDC could be genetic even in the absence of a family history. Our preliminary data suggest that the likelihood of IDC being genetic is similar among individuals with a positive family history and those without a family history of IDC. This is an important area of study for our group.

Guidelines for the genetic evaluation of individuals with DCM (>Genetic Evaluation of Cardiomyopathy: A Heart Failure Society of America Practice Guideline, 2018 ) include recommendations for clinical genetic testing. Genetic testing including the known genes is now widely available from testing laboratories. Since the Heart Failure Society guidelines have been published our group advocates clinical genetic testing should be done for patients with idiopathic DCM and their at-risk family members.

According to the Heart Failure Society of America (HFSA) guidelines (Genetic Evaluation of Cardiomyopathy: A Heart Failure Society of America Practice Guideline), it is recommended that family members of patients with idiopathic dilated cardiomyopathy (IDC) undergo clinical screening. Coronary heart disease, infectious causes and drug exposures must be ruled out before recommendations for family members are made. The guideline for genetic evaluation is based upon the knowledge that (1) FDC is diagnosed in 35-50% of patients with IDC, and (2) effective treatment for DCM is available. This guideline was created with consensus from experts in the field.

Comprehensive screening includes (1) a history and physical examination by a doctor or other trained health care provider, (2) an electrocardiogram (ECG) and (3) an echocardiogram.  Who should be screened in my family if I have a diagnosis of IDC? According to the HFSA guidelines, screening is recommended for parents, children, and siblings (i.e. first-degree relatives) of individuals with IDC. That is, if an individual is newly diagnosed with idiopathic dilated cardiomyopathy, we recommend screening of their first-degree relatives, regardless of whether those relatives are experiencing any symptoms.

The current HFSA guidelines recommend stepwise screening.

Stepwise screening is progressive evaluation of the first degree relatives of those shown to be affected.  For example, if a person is diagnosed with IDC, we would recommend screening of their first-degree relatives (parents, children, siblings). Screening of these first-degree relatives is step one. To take this example to step two, if the person’s father is found to be affected, then we would recommend that the first-degree relatives of the father also be screened. The first-degree relatives of the father include his parents (the paternal grandparents of the first person diagnosed), his brothers and sisters (the paternal aunts and uncles of the first person diagnosed), and his children, (the siblings of the first person diagnosed, for whom recommendations of screening were already made). This would be step two in stepwise screening. To continue the example, if in screening the first-degree relatives of the father, IDC is discovered in his sister, we would recommend screening of her first-degree relatives. This would be the step three in a stepwise screening of this family. Stepwise screening is recommended until all first-degree relatives of those affected with IDC have been screened.

At this time there are no formal recommendations for screening of more distantly related individuals (for example, second or third degree relatives – aunts, uncles, cousins, grandparents/grandchildren) of those who are affected. However, it is important to note that it is always appropriate to evaluate any individual with cardiovascular symptoms who has a family member with IDC. In some families with particularly aggressive disease, it may be appropriate to screen these more distant relatives regardless of whether or not they have symptoms.

Yes. A single normal screening can be reassuring; however, it does not completely eliminate the possibility that disease could develop in the future. Therefore, the HFSA guidelines recommend that first-degree relatives have an ECG and echocardiogram every 3-5 years. Between screenings, it is important to be aware of one’s cardiovascular health, and if anyone experiences cardiac symptoms (i.e. shortness of breath, dizziness, fainting, etc.), they should tell their doctor. Genetic testing can help to identify the family members who need periodic screening.

Cardiovascular screening for DCM may be offered to children. DCM is usually diagnosed during the adult years, and thus it is unlikely that younger children will have any symptoms or detectable abnormalities at cardiac evaluation, even if they carry a mutation that can cause DCM. However, in large families that have been selected for study for research purposes, our group has conducted evaluations of all available family members, including babies and children of all ages. The HFSA guidelines recommend that children who are first-degree relatives of an affected individual undergo a complete cardiovascular screening and, if normal, a repeat ECG and echocardiogram every 3-5 years. Of course, with any abnormal cardiac signs or symptoms, children (like adults) should undergo a complete cardiovascular exam and evaluation immediately. A child’s heart normally is growing and enlarging rapidly. For this reason it is more difficult to categorize a child’s heart size as “abnormal.” We recommend that cardiac screening for children be performed at expert pediatric cardiology centers.

Yes, DCM can be treated. Medical therapies such as angiotensin-converting enzyme (ACE) inhibitors and beta-blockers are very effective in improving heart function and even reducing heart size in most individuals. It is our hope that our project will lead to improved treatment for individuals with DCM.

Normal pregnancy demands extra work from the heart and may worsen an underlying weakness. Therefore, pregnant women with a family history of IDC (FDC) should be followed closely by both their obstetrician and cardiologist even if they have had previously healthy pregnancies. Women with IDC or FDC who are planning a family should consult a cardiologist to discuss the risks during and after pregnancy. Women with FDC should be alert to cardiac symptoms during pregnancy, and if symptoms occur, they should seek medical help immediately. Finally, women with IDC or FDC may also wish to speak with a genetic counselor regarding genetic testing and reproductive options.

We recommend that you tell your primary care doctor and cardiologist (if you have one) about your family history. This information can make a difference in your medical care, lifestyle recommendations, and the amount of surveillance recommended for you. Your physician may find the “Professionals” section of this website helpful in answering many of his or her own questions about FDC. If you have specific questions about your genetic risks that your physician is unable to answer, he/she should consider referring you to a genetic counseling professional. You may find a genetics provider in your area by searching the Resource Link on the home page of the National Society of Genetic Counselors or the American Board of Medical Genetics. You are also welcome to contact us with questions.

Because IDC, especially if familial, is known to have a genetic basis, sharing information about your health with your family members can help them to make important decisions about their own health. Knowing that DCM runs in the family can help your relatives to look out for and detect signs of the disease earlier than they might otherwise. This is important, as early detection of an enlarged heart or an arrhythmia can help people who have this disease live longer, healthier lives. For this reason, many people want to know if they or their loved ones are affected. Please also remember, however, that not everyone feels comfortable sharing personal health information, even with family members.

There is no substitute for one-on-one consultation with a knowledgeable health care provider. If you have a family history of DCM, you may be interested in discussing your personal risks with a cardiologist who is knowledgeable in genetics, a genetic counselor or geneticist. You may find a genetics provider in your area by clicking on “Find a Genetic Counselor” on the home page of the National Society of Genetic Counselors. You are also welcome to contact us with questions.

Keep good records of your own and your family members’ medical care. Hold onto your own and other family members’ medical records and death certificates, which may prove valuable in constructing your family history. Reach out to your family members to share family history information and recommendations for individuals with IDC. Discuss your concerns about personal or family members risk with a genetics professional. If possible, get involved in a research project that may help speed the identification of the genes involved in DCM and lead to improved treatments. Even if participation in research may not benefit you or your family directly, your participation will certainly benefit society by advancing knowledge in the field.

If you have IDC (regardless of family history), you can make an important contribution to research. If you are the family member of an individual with IDC, your participation would be very helpful. We would like to hear from you. Contact us.