What are the other Names for this Condition? (Also known as/Synonyms)

• DCM (Dilated Cardiomyopathy)
• Familial Dilated Cardiomyopathy
• Primary Dilated Cardiomyopathy

What is Dilated Cardiomyopathy? (Definition/Background Information)

• Dilated Cardiomyopathy (DCM) is a collective term used for heart muscle disorders leading to enlarged and weakened chambers of the heart (atria and ventricles). The condition particularly affects the lower left chamber (left ventricle)
• The left ventricle is the crucial pumping chamber of the heart. In DCM, its muscles get weak and dilated, with a consequent inability to contract effectively, affecting the pumping of blood
• Dilated Cardiomyopathy affects young, middle-aged, and older adults. Generally, men are affected much more than women; and, individuals of African descent more than Caucasians
• Several conditions can lead to the weakening of the heart muscles, and therefore, the risk factors for Dilated Cardiomyopathy are numerous. A few such factors include obesity, diabetes, autoimmune disorders, cancer therapies, drug and alcohol abuse, structural heart defects, coronary artery disease, and previous heart attack causing damage to heart muscle
• The most common cause of Dilated Cardiomyopathy is coronary artery disease. DCM can also be caused owing to gene mutations (20-35% of reported cases), or as a result of weakening of heart muscles due to infection, inflammation, chemicals and drugs. In some instances, the cause may not be known
• Early symptoms of Dilated Cardiomyopathy include shortness of breath, after a physical activity, and fatigue. Eventually, shortness of breath can develop without physical exertion, along with arrhythmia, low blood pressure, and fluid retention in organs and tissues. If the cause of DCM is an infection, fever and chills may also be present
• The diagnosis of Dilated Cardiomyopathy involves a thorough physical examination, symptom assessment, echocardiography (ECG), electrocardiography (EKG), stress test, imaging studies, and coronary catheterization. If required, a biopsy of the heart muscle may be ordered
• Some potential complications of the condition include backflow of blood into the heart (heart valve regurgitation), aberrant heart beats (arrhythmia), sudden cardiac arrest, and fluid build-up in tissues and organs
• Managing and treating the main disease/condition that causes the heart muscles to weaken is a priority. Depending on the severity of the condition, Dilated Cardiomyopathy may be treated with lifestyle changes, medications, non-surgical procedures, and through surgical implants. Heart transplantation may be recommended in some serious cases
• If Dilated Cardiomyopathy is inherited, it cannot be prevented. If it occurs because of other medical conditions, then getting suitable treatment for the same; leading an active life, losing excess weight, stoppage of smoking, discontinuing drug and alcohol use, and eating balanced nutritious meals, can help prevent DCM or delay its progression
• Dilated Cardiomyopathy is a progressive heart condition and the outcome is dependent upon the severity of the condition among other factors. Generally, the outcome is not favorable. Implantable devices for regulating heartbeats and heart transplantation may become necessary

Who gets Dilated Cardiomyopathy? (Age and Sex Distribution)

• Dilated Cardiomyopathy occurs at a frequency of 2-8 cases per 100,000 population
• DCM can occur at any age; however, a majority are reported in the age group of 20-65 years. Of the population with the condition, approximately 10% are above the age of 65
• Both male and female genders are affected; although, males are 3-times more likely to be diagnosed with the condition
• All races and ethnicities are susceptible to this heart condition. A comparative data shows that individuals of African descent are 3-times more likely to be affected with DCM than Caucasians

What are the Risk Factors for Dilated Cardiomyopathy? (Predisposing Factors)

The following are some known risk factors for developing Dilated Cardiomyopathy:

• A family history of the condition
• Coronary artery disease
• Prolonged and sustained tachycardia (increased heart rate)
• Chronic high blood pressure
• Previous history of heart attack causing damage to the heart muscles
• Obesity and sedentary lifestyle
• Uncontrolled diabetes
• Thyroid disease
• Viral or bacterial infection in the heart muscle
• Connective tissue disorders
• Neuromuscular diseases, such as muscular dystrophy
• Hemochromatosis
• Sarcoidosis
• Cancer treatments, such as chemotherapy
• Being on certain medications for psychiatric disorders
• Abuse of recreational drugs
• Alcoholism and heavy smoking
• HIV/AIDS infections
• Structural defects in the heart
• Heavy metal toxicity

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Dilated Cardiomyopathy? (Etiology)

Dilated Cardiomyopathy can either be primary or secondary. Whereas primary DCM is caused by heritable genetic changes in several genes, the secondary type develops from a pre-existing medical condition. The possible causative factors for DCM are explained below.

Mutations in over 30 genes have been reported for familial DCM. Of these, mutations in the TTN gene account for approximately 20%. The exact function of other gene mutations is not clear now, but it is believed that they contribute to abnormal contractions of heart muscle.

• The TTN gene codes for the protein “titin”, which is involved in the structural integrity and flexibility of sarcomeres, as well as their assembly. A sarcomere is the basic functional unit of heart muscle
• The sarcomeres are composed of thick and thin muscle filaments, which work in unison by attaching and releasing in a rhythmic manner, allowing the muscles to contract and relax, respectively. This process is necessary for the heart to pump blood
• When the gene is mutated, there is an abnormal shorter version of the titin protein synthesized, which is dysfunctional. The exact mechanism of how this causes Dilated Cardiomyopathy is unclear
• The majority of gene mutations associated with DCM are inherited in an autosomal dominant manner. In this type of inheritance, a single copy of the mutated gene in all the body cells is sufficient to cause the condition. An individual inherits the disease from an affected parent
• In a few cases, gene mutations are inherited in an autosomal recessive or X-linked manner
  • Autosomal recessive: An individual must have both copies of the causative gene in the defective form in every cell of his/her body for the disease to manifest itself. An affected individual inherits a defective gene copy from each parent. Parents are carriers of the disease and are typically not affected
  • X-linked inheritance: The defective gene is carried on the X chromosome. Since females have two X chromosomes, the unaffected gene copy masks the effects of a defective gene copy. However, since males have only one X chromosome inherited from their mother, the defective gene is expressed in them, resulting in the disease

Coronary artery disease: It is the most common cause of Dilated Cardiomyopathy.

• It leads to reduced blood supply to the heart muscles
• Injury and necrosis of heart muscles may occur, leading to formation of scar tissue
• The healthy tissue enlarges and extends to keep the muscles working
• The demands of the body are met temporarily. However, the expansion of muscles to balance the function of dead tissue leads to loss of flexibility in the heart muscle
• The heart muscle weakens, causing DCM

Other contributory factors may include:

• Chronic high blood pressure, which leads to thickening of the left ventricle
• Poorly-controlled diabetes: The exact cause is not known, but diabetes can cause structural changes in the heart
• Thyroid disease: The exact cause of heart muscle thickening as a consequence of decreased or increased thyroid hormone is not understood. Both conditions can cause changes in the consumption of oxygen by heart muscles, as well as muscle contractility in the heart
• Previous heart attack, damage to heart tissue
• Prolonged and sustained tachycardia (overworked heart muscles)
• Viral, bacterial, fungal or parasitic infections of the heart muscle can lead to weakening of the heart muscle. In order to keep the heart functioning, the weakened muscle gets over-worked, causing further weakening of the cardiac muscles and consequently DCM
• Hemochromatosis: A genetic condition that causes excess iron in the body. This can lead to iron toxicity in many organs, including the heart
• Sarcoidosis, which is a systemic disease that can affect several parts of the body, leading to the growth of small lumps of inflammatory cells. The disease affects the heart by causing abnormal rhythms and electrical conductivity abnormalities
• Neuromuscular diseases such as muscular dystrophy: Some gene mutations that cause dysfunction of skeletal muscle also cause aberrations in cardiac muscle. Therefore, progressive cardiac malfunctions are often observed with neuromuscular disorders
• Connective tissue disorders, such as rheumatoid arthritis and systemic lupus erythematosus, can cause weakness in heart muscle
• Infection by HIV or AIDS is considered to significantly contribute to the development of DCM in the affected individuals
• Alcoholism: Alcohol directly affects the heart muscle. When this is combined with improper nutrition, the effect is deleterious to the heart, causing erratic functioning
• Congenital structural abnormalities
• Chemotherapeutic drugs such as doxorubicin and daunorubicin
• Abuse of drugs (such as cocaine)
• Peripartum cardiomyopathy: It is a heart condition that develops in a woman either late in her pregnancy or within 5 months following delivery of the child. The exact cause of how this condition develops is not clear
• Heavy metal poisoning, due to exposure to metals such as lead, cobalt, arsenic and mercury

What are the Signs and Symptoms of Dilated Cardiomyopathy?

Dilated Cardiomyopathy can present with the following symptoms:

• Chest pain
• Dizziness, fainting
• Shortness of breath; shortness of breath while lying down (orthopnea)
• Fatigue
• Palpitations; a sensation of rapid fluttering or pounding heartbeat
• Heart murmurs: It is an unusual sound heard during the heartbeat. This can be an extra beat or whooshing/swishing sound, and may be faint or loud
• Swelling of ankles, legs, abdomen, or veins in the neck

Note: In addition to the above, the affected individuals may also exhibit other symptoms depending on their pre-existing medical condition.

How is Dilated Cardiomyopathy Diagnosed?

The diagnosis of Dilated Cardiomyopathy is made with the help of the following tools:

• A thorough physical examination and an assessment of symptoms
• Evaluation of personal and family medical history
• Blood test to check for infectious agents, toxins, and protein markers for heart disorders
• Chest X-ray to check for heart size, contour, and fluid build-up in lungs
• Other imaging tests of the heart, using techniques such as computed topography (CT) scan and magnetic resonance imaging (MRI) scan
• Electrocardiogram (EKG) to check the heart’s electrical activity
• Echocardiography (ECG or echo) uses sound waves to create a moving picture of the heart. This helps to check the size, shape, and pumping function of the heart
• Stress test: This test places stress on the heart by making it work harder and beat faster to determine, if the cardiac muscles can cope with the increased workload
• Cardiac catheterization: To check for pressure and blood flow in the heart’s chambers. It is often coupled with coronary angiography, in which a harmless dye is injected into the coronary arties and with the help of an X-ray, blood flow through heart and blood vessels can be observed
• Myocardial biopsy: A piece of the heart is removed and the cells are investigated for changes that may suggest damage to heart muscle. The biopsy can also provide information regarding ongoing myocardial infections, if any

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Dilated Cardiomyopathy?

The following complications may occur in individuals affected by Dilated Cardiomyopathy:

• Heart valve regurgitation: It causes the heart to pump ineffectively, such that blood flows back into the heart
• Arrhythmias: Abnormal heart rhythm, which can be triggered by physical exertion
• Sudden cardiac arrest (which can be unexpected)
• Embolism: Development of blood clots in the heart which may get into the bloodstream and obstruct blood supply to many important organs
• Edema: Fluid buildup in the lungs, abdomen, legs, and feet; all consequences of ineffective heart pumping
• Stroke

How is Dilated Cardiomyopathy Treated?

The treatment options for Dilated Cardiomyopathy may include the following:

• Treatment for primary medical conditions that led to DCM
• Lifestyle changes:
  • Adhering to a healthy diet that includes fresh fruits, vegetables, whole grains, fish and dairy products
  • Engaging in routine physical activity
  • Smoking cessation
  • Losing excess weight
  • Avoiding alcohol and illicit drugs
  • Getting enough sleep
  • Avoiding or reducing stress
• Prescription medications such as:
  • Beta blockers and calcium channel blockers, generally the first choice of medicines to treat cardiomyopathies, to regulate heartbeats
  • Angiotensin II converting enzyme (ACE) inhibitors and angiotensin II receptor blockers, to lower blood pressure
  • Digoxin, to improve heart function and increase activity level
  • Diuretics, to remove excess fluid and sodium
  • Electrolytes to aid in the proper functioning of muscles and nerve tissues
  • Anti-coagulants or blood thinners, which prevent blood clot formation
  • Anti-inflammatory drugs, to reduce inflammation 
• Non-surgical procedures such as alcohol septal ablation

Surgical procedures:

• Surgically-implanted devices
  • Implantable cardioverter defibrillator (ICD): It is a small device implanted in the chest or abdomen and connected to the heart via wires. The device helps control life-threatening arrhythmias that can lead to sudden cardiac arrest
  • Pacemakers
  • Left ventricular assist devices (LVADs) or heart pumps
• Heart pumps
• Heart transplantation, when required

How can Dilated Cardiomyopathy be Prevented?

Dilated Cardiomyopathy cannot be prevented, if the condition occurs as a result of inherited gene mutations.

• Genetic testing and counseling of prospective parents with a family history of the condition may help in understanding DCM better
• If DCM occurs secondary to any medical condition, then treatment of the primary factor may help decrease or delay the occurrence of the condition
• Regular medical screening at periodic intervals with tests and physical examinations are strongly recommended
• Some lifestyle changes, such as following a healthy diet, quitting cigarettes, reducing alcohol drinking, getting regular exercise and reducing stress, may help prevent the severity and complications from the condition
• In high-risk individuals, an implantable cardioverter defibrillator or a heart pump may help prevent sudden cardiac arrest, a potential complication of Dilated Cardiomyopathy

What is the Prognosis of Dilated Cardiomyopathy? (Outcomes/Resolutions)

• The prognosis of Dilated Cardiomyopathy may be good, if the primary medical condition causing the heart condition is treatable and manageable
• DCM is a progressive disease, and its severity determines the outcome. The 5-year survival of those affected by this heart condition is reported to be 30%
• If complications, such as heart valve regurgitation occur, the prognosis is poor

Additional and Relevant Useful Information for Dilated Cardiomyopathy:

Coronary artery disease is a major cause of Dilated Cardiomyopathy in North America.