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

• HCM (Hypertrophic Cardiomyopathy)

What is Hypertrophic Cardiomyopathy? (Definition/Background Information)

• Hypertrophic Cardiomyopathy (HCM) is a condition affecting the heart muscle. It is the most common cause of sudden cardiac arrest (SCA) in young adults and athletes
• The term “hypertrophic” means enlargement of cells, which, in this condition, leads to the following:
  • Thickening of the heart muscle; most commonly, of the wall that divides the 4 chambers of the heart
  • Thickening of the lower left chamber (left ventricle)
• The thickening also leads to changes in the arrangement of muscle cells. Normally, the cells are arranged parallel to each other to facilitate the contractility. However, in HCM, the organization of cells is disturbed (or in disarray), which negatively influences the conductivity of electrical signals in the lower chambers
• Although Hypertrophic Cardiomyopathy can develop at any age, the damage reportedly begins in early adulthood. Typically, the symptoms get manifested in young adults (between 20-30 years)
• About 60% of the Hypertrophic Cardiomyopathy cases are inherited. The exact cause of the non-inherited types is unknown. However, there can be spontaneous mutations leading to HCM. In addition, it can also develop secondary to various underlying medical conditions (including neurofibromatosis, hypertension, and advancing age)
• Hypertrophic Cardiomyopathy can be asymptomatic, or present with symptoms such as chest pain, shortness of breath, dizziness, fainting and palpitations. The diagnosis may involve tests such as echocardiography (ECG), electrocardiography (EKG), stress test, and coronary catheterization. If required, a biopsy of the heart muscle may be ordered
• Some potential complications of Hypertrophic Cardiomyopathy include a backflow of blood into the heart (heart valve regurgitation), aberrant heart beats (arrhythmia), sudden cardiac arrest, and dilated cardiomyopathy
• Hypertrophic Cardiomyopathy may be treated with lifestyle changes, medications, non-surgical procedures, and surgical implants, depending on the severity of the condition. With early diagnosis and prompt treatment, the prognosis of HCM is generally good
• However, in some individuals, a sudden cardiac arrest may the first presentation of the symptoms, which can even be fatal. Additionally, the severity of the causative medical condition in acquired HCM can affect the outcome
• Currently, there are no guidelines or methods available to prevent inherited forms of Hypertrophic Cardiomyopathy. Nevertheless, bringing about certain lifestyle changes and treating underlying medical conditions may help avoid or reduce the severity of HCM symptoms

Hypertrophic Cardiomyopathy can be classified on the basis of whether it is inherited or acquired (secondary to a pre-existing condition):

• Familial Hypertrophic Cardiomyopathy, where the condition is inherited from an affected parent, as an autosomal dominant trait
• Acquired Hypertrophic Cardiomyopathy, where the condition develops because of a chronic, pre-existing condition, such as the following:
  • Pituitary tumors causing abnormal increase in growth hormone production, leading to acromegaly
  • Neurofibromatosis, which can cause tumors in the brain and spinal cord
  • Lipodystrophy; a disease with abnormality in body fat storage and utilization
  • Pheochromocytoma; an adrenal gland tumor that produces hormones
  • Poorly-controlled diabetes
  • Thyroid disease
  • High blood pressure
  • Aging

Functionally, HCM can be classified as obstructive or non-obstructive type:

• Hypertrophic Obstructive Cardiomyopathy (HOCM):
  • Blood flow blockage occurs in the left ventricle, forcing it to exertion, to pump blood to the rest of the body
  • It can also affect the mitral valve of the heart and cause blood to leak backward through the valve
• Hypertrophic Non-Obstructive Cardiomyopathy (HNCM):
  • There is no blockage to blood flow in this condition
  • However, the pumping of blood becomes inefficient, when a part, or all of, the left ventricle becomes thicker

In both types, the heart muscle, particularly the left ventricle, gets thickened, causing the inside of the left ventricle to become smaller. This reduces the capability of the left ventricle to relax sufficiently and hold enough blood.

Who gets Hypertrophic Cardiomyopathy? (Age and Sex Distribution)

• Hypertrophic Cardiomyopathy can be present at any age, ranging from newborns to elderly individuals. However, the most common age of presentation is in the third decade of life
• There is no racial or gender bias in the occurrence of HCM
• The incidence rate for the inherited form of HCM, which is the most common form, is about 1:500

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

The following are some risk factors for Hypertrophic Cardiomyopathy:

• Having a family history of the condition
• Certain chronic conditions and diseases such as:
  • High blood pressure
  • Diabetes
  • Thyroid disease
  • Lipodystrophy
  • Pituitary tumors leading to acromegaly
  • Tumors in the brain and spinal cord, such as in neurofibromatosis
  • Adrenal gland tumors called pheochromocytoma
• Smoking, heavy alcohol drinking and drug abuse, that can contribute to or worsen high blood pressure
• Obesity
• Sedentary lifestyle

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 Hypertrophic Cardiomyopathy? (Etiology)

Hypertrophic Cardiomyopathy may occur as a primary or secondary condition. The primary form is caused by inherited gene mutation(s). The secondary type develops as the result of a pre-existing condition.

The known causes of HCM include: Mutations in the MYH7, MYBPC3, TNNT2, TNNI3, and some unidentified genes.

• Under normal circumstances, these genes code for proteins involved in the formation of muscle structures called sarcomeres, which help the heart muscles contract properly. 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
• The following are some known gene functions:
  • MYH7: It codes for cardiac β myosin heavy chain, a crucial component of thick filament
  • MYBPC3: It codes for cardiac myosin binding protein, associates with the thick filament and provides structural integrity required for contractions
  • TNNT2: It codes for cardiac troponin T, which is 1 of the 3 proteins of the troponin complex in thin filaments, required for muscle contractions and relaxations
  • TNNI3: It codes for cardiac troponin 1, also a part of the troponin complex
• When there is a mutation in one or many genes involved in this process, it may result in altered proteins or loss of proteins in the sarcomeres, interfering with cardiac function. However, the link between compromised sarcomere function and thickening of cardiac muscles is not well understood
• The mutations are inherited in an autosomal dominant manner. In this type of inheritance, a single copy of a defective gene in every cell of the individual is sufficient to cause disease. Typically, one inherits the condition from an affected parent
• Spontaneous mutations may also be observed in some cases; although, the exact reason and nature of these mutations is not yet well understood

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
• Lipodystrophy: It is a genetic condition that results in abnormal formation, storage and distribution of fat. Individuals with a mutation in seipin, an integral membrane protein, exhibits a strong correlation with cardiomyopathy. The majority of affected individuals have insulin-resistant diabetes, high cholesterol and triglyceride levels, all of which can lead to thickening of the heart muscle
• Acromegaly: Abnormal increase in growth hormone, as a result of a benign pituitary tumor, can cause aberrant growth of external and internal tissue. The thickening of heart muscles is a known outcome of this disorder
• Pheochromocytoma: It is an adrenal gland tumor that can cause acute or chronic high blood pressure in the affected individual. The blood pressure changes are caused by the release of catecholamines, which control involuntary muscle movement in the body, such as those of the heart
• Neurofibromatosis: The tumors formed in this genetic condition are known as neurofibromas that cause high blood pressure to develop in the affected individuals

What are the Signs and Symptoms of Hypertrophic Cardiomyopathy?

The signs and symptoms associated with Hypertrophic Cardiomyopathy include:

• Chest pain
• Dizziness, fainting
• Shortness of breath, particularly with physical exertion (exertional dyspnea)
• Shortness of breath, while lying down (orthopnea)
• Shortness of breath and coughing while sleeping (nocturnal paroxysmal dyspnea)
• 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 some cases, the condition may be completely asymptomatic and sudden fainting may be the first presentation of Hypertrophic Cardiomyopathy
• Individuals with non-obstructive cardiomyopathy are reported to present milder symptoms in general, when compared to those with obstructive HCM
• In acquired HCM, additional symptoms pertaining to the causative chronic condition may be present

How is Hypertrophic Cardiomyopathy Diagnosed?

For an accurate diagnosis of Hypertrophic Cardiomyopathy, the following tests and exams may be required:

• A thorough physical examination and an assessment of symptoms
• Evaluation of personal and family medical history
• Chest X-ray to check for heart size, contour, and fluid build-up in lungs
• 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 Hypertrophic Cardiomyopathy
• Genetic testing to seek confirmation of the diagnosis, in cases of inherited HCMs. This may be recommended for the whole family, which can help understand if the condition is inherited

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 Hypertrophic Cardiomyopathy?

Hypertrophic Cardiomyopathy can lead to following complications:

• 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): This condition is the cause of sudden cardiac arrests in young individuals and athletes
• 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
• Heart failure that is caused by poor blood flow to the heart
• Dilated cardiomyopathy: It results from the heart muscles becoming inefficient, such that the pumping of blood is seriously compromised

How is Hypertrophic Cardiomyopathy Treated?

The treatment options for Hypertrophic Cardiomyopathy may include the following:

• 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 of stress
  • Seeking treatment for underlying conditions (such as diabetes, high blood pressure, etc.)
• Beta blockers and calcium channel blockers, generally the first choice of medicines to treat cardiomyopathies, to regulate heartbeats
• Other prescription medications may help in:
  • Regulating high blood pressure levels
  • Slow heart rate
  • Maintain normal heart beat rhythm
  • Balance electrolytes in the body; electrolytes are minerals that help in the proper functioning of muscles and nerve tissues
  • Removing excess fluid and sodium
  • Preventing blood clot formation (through anti-coagulants or blood thinners)
  • Reducing inflammation
• Non-surgical procedures, such as alcohol septal ablation, in which:
  • Ethanol (a type of alcohol) is injected into a small artery
  • The alcohol kills cells in the tissue, to shrink the heart muscle to a more ‘normal’ size
  • This improves blood flow through the ventricles, which in turn improves the symptoms

Surgical procedures:

• Septal myectomy:
  • It is a type of open-heart surgery that is typically used for obstructive Hypertrophic Cardiomyopathy with severe symptoms
  • The procedure is usually recommended for young patients with poor response to medicines
  • It helps in improving blood pumping by removing part of the thickened heart muscle
• Surgically-implanted devices such as 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

How can Hypertrophic Cardiomyopathy be Prevented?

Hypertrophic Cardiomyopathy is predominantly a genetic condition, and therefore, there are no guidelines or specific methods for preventing the condition from developing.

• Genetic testing of the expecting parents (and related family members) and prenatal diagnosis (molecular testing of the fetus during pregnancy) may help in understanding the risks better during pregnancy
• If there is a family history of the condition, then genetic counseling will help assess risks, before planning for a child
• Active research is currently being performed to explore the possibilities for treatment and prevention of inherited and acquired genetic disorders such as HCM
• 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
• If HCM occurs secondary to a pre-existing medical condition, then seeking treatment for that disorder may help an affected individual reduce the chance of its occurrence
• In high-risk individuals, an implantable cardioverter defibrillator may help prevent sudden cardiac arrest, a potential complication of Hypertrophic Cardiomyopathy

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

The prognosis of Hypertrophic Cardiomyopathy depends on timely and appropriate treatment.

• Without treatment, the symptoms can worsen resulting in severe complications
• Treatment can prevent worsening of HCM, control symptoms, and reduce complications, leading to better outcomes
• In some cases, sudden cardiac arrest even at first presentation of the disease, may be fatal
• The prognosis of acquired HCM may be determined by the seriousness of the pre-existing condition(s), timely diagnosis, as well as the beginning of, and response to, treatment

Additional and Relevant Useful Information for Hypertrophic Cardiomyopathy:

Please visit our Heart & Vascular Health Center for more physician-approved health information:

http://www.dovemed.com/healthy-living/heart-center/