Hypertrophic Cardiomyopathy

Topic Overview

What is hypertrophic cardiomyopathy?

Hypertrophic cardiomyopathy is a genetic disease in which the heart muscle thickens abnormally. The thickened heart muscle can interfere with the heart's electrical system, increasing the risk for life-threatening abnormal heartbeats (arrhythmias) and, rarely, sudden death. In some cases, the enlarged heart muscle is unable to relax between heartbeats as it normally does, and the heart muscle itself does not get enough blood or oxygen. In rare cases, the thickened heart muscle reduces the heart's ability to pump blood effectively to the body.

See an illustration of a normal heart compared with a heart with hypertrophic cardiomyopathy .

What causes hypertrophic cardiomyopathy?

Researchers have identified defective genes that cause the heart muscle fibres to grow abnormally, resulting in hypertrophic cardiomyopathy. People with family members who have had hypertrophic cardiomyopathy are at an increased risk for developing this condition and, as a result, have a slightly higher risk of early death than the general population.

In about 50% of cases, people inherit hypertrophic cardiomyopathy from their parents. In most of the remaining cases, fetuses probably develop a gene mutation during the early stages of development before birth. This mutation causes abnormal growth of heart tissue.¹

What are the symptoms?

Even though hypertrophic cardiomyopathy can cause serious health problems and even sudden death, you may never have any symptoms of the disease. Many people with the disease live normal lives with very few problems. These people may never even be treated for hypertrophic cardiomyopathy.

Symptoms of hypertrophic cardiomyopathy may occur at any time of life. You may have had hypertrophic cardiomyopathy for a long time, but just recently started having symptoms. The most common symptoms are shortness of breath, chest pain (angina), heart palpitations, and fainting or near-fainting (syncope), especially with physical activity. Sometimes life-threatening abnormal heartbeats (arrhythmias) cause fainting and heart palpitations—these are symptoms that you should always report to your doctor because of your increased risk of sudden death.

In rare cases, the thickened heart muscle becomes unable to pump enough blood to meet the body's needs. This is called heart failure. Symptoms of heart failure include fluid buildup (edema), especially in the legs, ankles, and feet; shortness of breath and a dry, hacking cough, especially while lying down; increased urination at night; nausea; and abdominal swelling, tenderness, or pain.

How is hypertrophic cardiomyopathy diagnosed?

Your doctor will review your medical history, ask about any family history of heart disease or early and sudden death, and perform a thorough physical examination, including listening to your heart and lungs and checking your legs for fluid buildup. An electrocardiogram (ECG or EKG), chest X-ray, echocardiogram, routine blood tests, and other medical tests are usually needed to confirm a diagnosis.

If someone in your immediate family, such as a parent or sibling, has hypertrophic cardiomyopathy or died suddenly at a young age, you are at risk and should have routine echocardiograms and other medical tests to screen for the condition.² So far, routine genetic testing is not yet practical because there are so many possible abnormal genes that cause the disease.

How is it treated?

Many people with hypertrophic cardiomyopathy do not need treatment. But in some cases, having a thickened heart muscle can cause problems.

About one in four people with hypertrophic cardiomyopathy develop atrial fibrillation, an irregular and rapid heart rhythm.² Atrial fibrillation is usually treated with electrical cardioversion, which is an electrical shock to return the heart to its normal rhythm, and/or medicines to control the heart rate and rhythm. Doctors also often recommend anticoagulant medicines to slow blood clotting and prevent stroke in these people.

An estimated 5% to 10% of people with hypertrophic cardiomyopathy develop heart failure and progressive symptoms.¹ In these people, heart failure is treated with medicines to improve heart function. If heart failure becomes severe and does not improve with medicines, surgery to remove or reduce overgrown heart muscle may be recommended.

All people with hypertrophic cardiomyopathy—whether their symptoms are mild or severe—are at a higher risk for sudden death than the normal population and can die at a young age. While studies indicate that hypertrophic cardiomyopathy causes fewer deaths (1% per year of adults with hypertrophic cardiomyopathy) than once thought,³ most people with hypertrophic cardiomyopathy should be assessed by a cardiologist to determine their risk. For those in a high-risk category, an implantable cardioverter-defibrillator appears to be the best way to prevent sudden death. An implantable cardioverter-defibrillator, or ICD, is a small device like a pacemaker used mainly to control life-threatening heart rhythms.

How can I live with hypertrophic cardiomyopathy?

Even though hypertrophic cardiomyopathy can cause serious health problems and even sudden death, you may never have any symptoms of the disease. Many adults diagnosed with hypertrophic cardiomyopathy do very well and survive to old age. It seems that children diagnosed with hypertrophic cardiomyopathy have the greatest risk for severe health problems as a result of this disease.

Because of the risk of sudden death, it is important for people with hypertrophic cardiomyopathy to avoid strenuous activity and intense exercise.

Getting moderate exercise under your doctor's supervision, eating a low-fat diet, and avoiding alcohol overuse are all ways to promote a healthy heart. Your doctor will recommend regular office visits to monitor this condition.

Frequently Asked Questions

Learning about hypertrophic cardiomyopathy:	Who is affected by hypertrophic cardiomyopathy? Are there different types of hypertrophic cardiomyopathy? What are the symptoms of hypertrophic cardiomyopathy?
Being diagnosed:	How is hypertrophic cardiomyopathy diagnosed?
Getting treatment:	How is hypertrophic cardiomyopathy treated?
Living with hypertrophic cardiomyopathy:	What can I do to take care of myself?

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Author:	Douglas Dana Monica Rhodes	Last Updated: February 12, 2007
Medical Review:	Anne C. Poinier, MD - Internal Medicine Kathleen Romito, MD - Family Medicine Stephen Fort, MD, MRCP, FRCPC - Interventional Cardiology
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