Hypertrophic Cardiomyopathy

The heart muscle is responsible for circulating blood throughout the body. Circulation can be compromised by heart disease such as cardiomyopathy. Cardiomyopathy is a condition characterized by the wall of the heart muscle becoming thick, enlarged or stiff. This can lead to the heart becoming weaker and being unable to pump blood efficiently. As it works harder to pump blood, it may also be unable to relax and fill with blood.

Hypertrophic cardiomyopathy (HCM) is generally an inherited condition that can variably be passed down through families. The condition occurs when the heart-muscle wall thickens inward, creating less space for blood inside the heart. In many cases, only one part of the heart thickens, most commonly the septum, which divides the right from the left main cardiac chambers (ventricles).

There are two types of HCM:

  • Obstructive hypertrophic cardiomyopathy: Occurs when the thickened septal wall and parts of the mitral valve block the blood outflow from the left ventricle.
  • Nonobstructive hypertrophic cardiomyopathy: When the thickening of the ventricle wall does not block blood outflow from the left ventricle.

Symptoms

Some patients with HCM have no symptoms (asymptomatic), while others may experience life-threatening symptoms. Both obstructive and nonobstructive hypertrophic cardiomyopathies can cause symptoms. The most common symptoms patients experience may include:

As HCM worsens, symptoms of heart failure may become evident. HCM in young adults is often more severe than HCM in older patients. In affected persons, collapse and sudden death may be the first symptom. This can be caused by dangerous arrhythmia or by a blockage of blood outflow to the rest of the body.


Causes and Risk Factors

HCM is generally caused by an inherited genetic mutation (abnormality). Patients with HCM also have a related condition known as myofiber disarray, an abnormal arrangement of the heart muscle cells that is one possible cause for the development of arrhythmia. There are also forms of HCM that are not inherited but are caused by abnormal depositions in the heart muscle or from intense physical training, high blood pressure or heart valve disease.

Patients of any age, gender or ethnicity can develop HCM. Young adults are generally at higher risk for sudden death.

Diagnosis

Diagnosis of HCM will generally begin with the physician taking a medical history and performing a physical exam. During the physical exam, the physician will listen to the patient's heart and lungs to see if there are any abnormal heart sounds, such as a murmur. Patients are also asked for a detailed description of their symptoms.

After the physical exam, the physician may order tests to examine the thickness of the heart muscle, the blood flow through the heart, and any potential leaking of the heart valves. An echocardiogram is a noninvasive procedure using ultrasound waves to visualize heart structures and measure blood flow within the heart. Exercise stress testing and other maneuvers combined with an echocardiogram can be useful to detect obstructive HCM. Alternative imaging tests, such as a cardiac MRI, may be used to see the thickening of the walls — if the echocardiogram is inconclusive.

An electrocardiogram (EKG) is also noninvasive and may be used to examine the electrical activity of the heart. In some cases, it may be important to monitor the electrical activity over the course of one to 14 days to rule out intermittent irregular heart beats. To do this, a portable device known as a Holter monitor or Ziopatch® is used.

Rarely, invasive cardiac catheterization may be used to measure the blood pressure inside the heart.

Treatments

Treatment of HCM will vary from one patient to another, and it will depend on the severity of the condition and symptoms. In some cases, when the patient has no symptoms, lifestyle changes and observation may be all that is needed. For patients with symptoms that affect their lifestyle, medications and surgery (only in rare cases) may be needed to treat the condition.

Lifestyle changes can often help manage HCM symptoms. Maintaining a healthy weight and diet are important for managing HCM. Engaging in physician-approved exercise may also be prescribed. Cedars-Sinai's Nutrition Counseling Services and New Leaf Personal Exercise Program may be part of the interdisciplinary healthcare team, in order to provide guidance and assistance to patients seeking lifestyle changes.

Medications such as beta blockers or calcium channel blockers may be used to slow the heartbeat and relax the heart muscle so that it can work more efficiently. Other useful medications include disopyramide (Norpace®) and ranolazine (Ranexa®). In addition, Cedars-Sinai frequently participates in clinical trials in which new therapies are being tested.

The vast majority of patients can live a normal life using a personalized medication regimen prescribed by our experienced physicians. Only in rare cases is surgery (myectomy) or catheter-based intervention (septal alcohol ablation) needed to remove or minimize the thickened portion of the heart wall. Some HCM patients may require a defibrillator or pacemaker.

The knowledgeable and highly trained staff at the Cedars-Sinai Cardiogenetics Program will work with each patient to determine the best treatment option.