Hypertrophic Cardiomyopathy

Overview

Hypertrophic cardiomyopathy (HCM) is a disease in which the heart muscle, particularly the wall of the main pumping chamber (the left ventricle), becomes abnormally thick. This thickening can make it harder for the heart to fill with and pump blood, and in some people it partly blocks the flow of blood out of the heart.

HCM is most often inherited and is one of the most common genetic heart conditions. Many people with HCM have few or no symptoms and live normal lives, but others develop symptoms such as chest pain, shortness of breath, or palpitations. Importantly, HCM is a leading cause of sudden cardiac arrest in young people and athletes, which is why diagnosis and appropriate management are so important.

Symptoms

Symptoms vary greatly. Some people never have any, while others develop them at any age. Possible symptoms include:

• Shortness of breath, especially with exertion.
• Chest pain or pressure, particularly during physical activity.
• Palpitations, a sensation of a racing, pounding, or fluttering heartbeat.
• Lightheadedness or dizziness.
• Fainting (syncope), especially during or just after exercise, which is an important warning sign.
• Fatigue.

For some individuals, sudden cardiac arrest is the first sign of the condition. Fainting during exercise, severe chest pain, or a sudden collapse should be treated as a medical emergency.

Causes

Hypertrophic cardiomyopathy is most commonly caused by inherited changes (mutations) in genes that control the proteins of the heart muscle. These changes cause the muscle to grow abnormally thick and stiff. Key points about the cause include:

• It often runs in families, and a person with HCM can pass the gene to their children.
• It is usually present from birth as a genetic tendency, though the heart thickening may not appear until adolescence or adulthood.
• Not everyone who inherits a gene change develops noticeable disease, and severity can vary even within the same family.

In some cases, no clear genetic cause is found, and rarely, other conditions can cause heart muscle thickening that resembles HCM.

Risk Factors

The main risk factor for HCM is having a family member with the condition:

• A parent, sibling, or child with HCM, since it is inherited and each child of an affected parent may carry the gene.
• A family history of unexplained sudden death, particularly at a young age.

Because of the genetic nature of the disease, relatives of someone with HCM are often advised to be screened, even if they feel completely well.

Diagnosis

HCM may be discovered during evaluation of symptoms, after detecting a heart murmur, during family screening, or as part of sports physicals. Diagnosis typically involves:

• Echocardiogram, an ultrasound of the heart that measures the thickness of the heart muscle and how well it pumps; this is the main test.
• Electrocardiogram (ECG), which records the heart's electrical activity and is often abnormal.
• Cardiac MRI, which gives detailed images of the heart muscle.
• Monitoring of heart rhythm to detect abnormal rhythms.
• Genetic testing and family screening, which can identify relatives at risk.

Doctors also assess each person's individual risk of dangerous heart rhythms to guide treatment.

Treatment

Treatment is tailored to symptoms and to each person's risk of complications. Goals are to relieve symptoms and reduce the risk of sudden cardiac arrest. Options include:

• Medications to relax the heart, slow the heart rate, ease the obstruction to blood flow, and control abnormal rhythms.
• An implantable cardioverter-defibrillator (ICD) for people at high risk of dangerous heart rhythms, which can deliver a shock to restore a normal rhythm.
• Procedures to reduce thickened muscle that blocks blood flow, such as surgical removal of part of the muscle (septal myectomy) or a catheter-based procedure (alcohol septal ablation), in selected patients.
• Activity guidance, as people with HCM may be advised to avoid certain intense competitive sports, based on individual evaluation.
• Regular follow-up and family screening.

Prevention

Because HCM is usually genetic, it cannot be prevented, but its risks can be managed:

• Family members of someone with HCM should consider screening with their doctor, even without symptoms.
• Follow your cardiologist's advice on safe physical activity and which sports to avoid.
• Attend regular follow-up appointments and take prescribed medications.
• Learn the warning signs that require urgent care, and make sure family members know them too.

When to See a Doctor

See a healthcare provider if you have symptoms such as chest pain, shortness of breath, palpitations, dizziness, or fainting, especially with exertion, or if a close relative has HCM or died suddenly at a young age.

Call emergency services immediately if you or someone else experiences fainting during exercise, severe or persistent chest pain, a sudden collapse, or signs of cardiac arrest such as no pulse and no breathing. If someone collapses and is not breathing normally, start CPR and use an automated external defibrillator (AED) if available while help is on the way.

Related Topics

Frequently Asked Questions

References

1. American Heart Association.
2. Mayo Clinic. Hypertrophic cardiomyopathy.
3. National Heart, Lung, and Blood Institute (NHLBI).
4. MedlinePlus, U.S. National Library of Medicine.