Cardiomyopathy is a disease of the heart muscle. Many types are genetic, and a person may inherit them from a parent. These types are known as inherited cardiomyopathies.

Cardiomyopathy is a group of diseases that damage the heart muscle. These diseases can make it difficult for the heart to pump blood around the body. Most types of cardiomyopathy cause the heart muscle to enlarge, stiffen, or become too thin or too thick.

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Dilated cardiomyopathy (DCM) affects the heart’s ventricles and atria. The ventricles are the lower chambers in the heart, and the atria are the upper chambers.

DCM causes the muscle in the heart to dilate, stretch, and become thinner. As a result, the interiors of the heart’s chambers become larger.

DCM also causes the heart muscle to contract abnormally, which affects the heart’s ability to effectively pump blood. This weakening of the heart muscles can also cause heart failure.

Health experts estimate that DCM occurs at a rate of 36 cases per 100,000 people. However, the true number may be greater, since many people do not have symptoms and do not receive a diagnosis.

Symptoms of DCM

DCM may not cause symptoms for a long time. When symptoms occur, they can include heart failure symptoms such as:

Inheritance of DCM

DCM can be genetic. This means it can pass down from a parent to a child. Medical professionals associate DCM with variations in certain genes, including those involved in the production of the following proteins:

  • Titin: a protein that provides structure, flexibility, and stability to heart muscle
  • Desmin: a protein involved in the development of skeletal and cardiac muscle
  • Lamin A and lamin C: proteins involved in maintaining the structural stability of cells
  • Myosin: a protein involved in muscle contraction

Hypertrophic cardiomyopathy (HCM) is a condition that causes the walls of the heart’s left ventricle to stiffen, impairing the flow of blood out of the heart. HCM affects about 1 in 500 adults.

Symptoms of HCM

People with HCM may not show any signs or symptoms. In some cases, people may have no symptoms in the early stages but may develop symptoms over time.

Possible symptoms include:

  • chest pain and shortness of breath, particularly when exercising
  • fatigue
  • heart palpitations, which are periods of a rapid or irregular heartbeat
  • dizziness
  • lightheadedness
  • fainting
  • swelling

Inheritance of HCM

In about 60% of people with HCM, the condition has a clear genetic inheritance pattern due to inherited gene alterations. In these cases, medical professionals classify the condition as autosomal dominant.

Medical professionals associate HCM with variations in the gene that is responsible for contractile elements in the heart.

Arrhythmogenic right ventricular dysplasia (ARVD), also known as arrhythmogenic right ventricular cardiomyopathy, occurs when the muscle tissue in the heart’s right ventricle dies and scar tissue takes its place. ARVD can then disrupt the heart’s electrical signals, causing a person to develop arrhythmias.

ARVD affects about 1 in 5,000 people. It may account for 5–10% of sudden unexplained deaths in people younger than 65 years of age. AVRD can also affect teenagers and young adults and can cause sudden cardiac arrest in young athletes.

Symptoms of ARVD

Common symptoms of ARVD include:

In some cases, ARVD may cause cardiac arrest during exercise.

Inheritance of ARVD

A person typically inherits ARVD. Medical professionals typically classify it as an autosomal dominant condition.

Around 40–50% of people with ARVD have a variation in genes that are responsible for creating desmosome proteins. These are proteins that help mediate cell-to-cell contact and hold cells together.

Restrictive cardiomyopathy (RCM) causes the heart’s ventricles to become rigid. This occurs when abnormal tissue replaces normal heart muscle. In RCM, the ventricles do not relax normally and fill with blood, causing the atria to enlarge.

Over time, RCM causes blood flow in the heart to reduce, which can lead to heart failure and arrhythmias. RCM is a less common cause of cardiomyopathy.

Symptoms of RCM

Possible symptoms of RCM include heart failure symptoms such as shortness of breath, low exercise tolerance, swelling, and fatigue, as well as heart palpitations. In some cases, a person may experience sudden cardiac arrest.

Inheritance of RCM

RCM can occur due to genetic changes. People usually inherit RCM in an autosomal dominant manner, but a person may also acquire the condition without inheriting it.

The most common cause of RCM in the United States is amyloidosis, a condition in which a protein called amyloid builds up in a person’s body. Amyloidosis can be hereditary.

Transthyretin amyloid cardiomyopathy (ATTR-CM) is a potentially fatal disease of the heart muscle.

When a person has ATTR-CM, a protein called transthyretin becomes misshapen and builds up in the heart. When these protein deposits collect in the heart, they can cause the walls of the heart to stiffen. As a result, the left ventricle may be unable to relax and may fill with blood.

There is not much information on the prevalence of ATTR-CM. However, a 2022 research article suggests that ATTR-CM is more common than experts previously thought.

Symptoms of ATTR-CM

Symptoms of ATTR-CM can be subtle, and doctors may misdiagnose it as another condition.

In the early stages, ATTR-CM can cause signs and symptoms similar to those of other conditions, such as heart failure from other causes and high blood pressure. People may also experience seemingly unrelated symptoms such as carpal tunnel syndrome and nerve problems.

Some people may have no symptoms at all. In some cases, a person may progress to end stage heart failure.

Inheritance of ATTR-CM

There are two types of ATTR-CM. Medical professionals refer to one type as hereditary ATTR-CM and the other as wild-type ATTR-CM.

Hereditary ATTR-CM can run in families, and a person can inherit it from their parents.

Chromosome 18 carries the gene responsible for creating the transthyretin protein. A change in this gene can lead to structural changes in transthyretin, which can cause ATTR-CM to develop.

Treatment for inherited cardiomyopathies aim to:

  • stop the disease from worsening
  • manage or treat any underlying causes of the disease
  • manage conditions that may cause the disease to worsen
  • reduce complications
  • reduce the risk of a sudden cardiac arrest
  • manage symptoms to help improve a person’s quality of life

Below are some of the treatment options for inherited cardiomyopathies.

Medications for inherited cardiomyopathies

A medical professional may prescribe medications that aim to:

  • Lower a person’s blood pressure: Medications doctors use to lower blood pressure include:
  • Slow the heart rate: Medications doctors use to slow a person’s heart rate include:
    • beta-blockers
    • calcium channel blockers
    • digoxin
  • Maintain a normal heart rhythm: Doctors may prescribe antiarrhythmic medications to prevent a person from developing arrhythmias.
  • Balance electrolytes: Electrolytes are minerals that help maintain fluid levels in the body. They can help muscle and nerve tissues function. Doctors may prescribe aldosterone blockers to help balance a person’s electrolytes.
  • Remove excess fluid and sodium: Doctors may prescribe diuretics to help remove excess fluid and sodium from a person’s body.
  • Prevent blood clots: A doctor may prescribe anticoagulants to treat or prevent blood clots in those with certain inherited cardiomyopathies or related arrhythmias, such as atrial fibrillation.

Procedures for inherited cardiomyopathies

A medical professional may decide to use a range of surgical or nonsurgical procedures to treat inherited cardiomyopathies.

These include:

  • Surgically implanted devices: A surgeon may implant a number of devices to help improve the heart’s function, such as:
  • Heart transplant: In some cases, a person may benefit from a heart transplant. This involves removing the heart and replacing it with a healthy heart from a donor. This is often a last resort for people with end stage heart failure.
  • Septal myectomy: This is a form of open heart surgery that doctors use to treat HCM. During this procedure, a surgeon removes a portion of the thickened septum that bulges into the left ventricle. This procedure can help improve blood flow through the heart.
  • Alcohol septal ablation: In this nonsurgical procedure, a doctor injects ethanol through a tube into the artery that supplies blood to the heart muscle. This is a treatment option for people with HCM. It causes cells in the thickened heart muscle to die, which in turn causes thickened heart tissue to shrink.

Lifestyle strategies for inherited cardiomyopathies

A person with an inherited cardiomyopathy may also choose to use some of the following lifestyle strategies to help manage their condition, if applicable:

Cardiomyopathy is a group of diseases that affects the muscles in the heart. Many types of cardiomyopathy are genetic, which means a parent can pass them down to their children.

Treatment options will vary depending on the type of cardiomyopathy. Possible treatments include medications to help lower the blood pressure, slow the heart rate, maintain a normal heart rhythm, and prevent blood clots, as well as surgery and the implantation of devices to help improve the heart’s function.