Hypertrophic Cardiomyopathy and Heart Failure

About 5.8 million people in the United States suffer from heart failure and nearly 700,000 new cases are diagnosed each year. Heart failure usually develops slowly over time, and some loss in pumping capacity is natural as people age. With end-stage heart failure, however, that loss becomes life- threatening and is no longer manageable through medical therapies.

One of the many causes of heart failure is cardiomyopathy. There are two major types of cardiomyopathy: primary cardiomyopathy, defined as changes in the structure or function of the heart muscle that cannot be attributed to a specific cause, and secondary, which is associated with disorders of the heart or other organs. Congestive cardiomyopathy is the most common primary form of heart muscle disease. Other types include hypertrophic and restrictive cardiomyopathy. Heart muscle disease related to coronary artery disease is called ischemic cardiomyopathy.

The exact frequency of cardiomyopathy is difficult to determine as many cases are not severe, but about 500,000 new cases develop each year in the United States. Instead of afflicting the elderly like most other heart diseases, heart muscle disease more commonly strikes younger people. This group of disorders directly damages the muscle, impairing its ability to pump blood to other parts of the body. 

Dr. Hiroo Takayama – What is hypertrophic cardiomyopathy?

Hypertrophic Cardiomyopathy

In congestive cardiomyopathy, also called dilated cardiomyopathy, the heart becomes stretched and weakened and is unable to pump effectively. Symptoms of heart failure develop.

While HCM can involve both lower chambers of the heart, it usually affects the left ventricle (the main pumping chamber). The muscle fibers of the heart thicken, making it harder for the heart to relax and let new blood into the chambers.Hypertrophic cardiomyopathy (HCM), in contrast to the congestive type, involves thickening of the heart muscle, usually that of the left ventricle, but sometimes the right chamber is also involved. In one form of hypertrophic disease, the septum—the wall between the two ventricles—becomes enlarged and obstructs the flow of blood from the left ventricle into the aorta. The mitral valve also may be distorted by the thickened septum, leading to mitral insufficiency. The major symptoms are shortness of breath, dizziness or fainting, chest pain, and cardiac arrhythmias.

Because the symptoms of HCM mimic those in many other conditions, it is often misdiagnosed as exercise-induced asthma, mitral valve prolapse, or anxiety/depression.

While HCM involves a structural abnormality in the heart muscle, patients often have conduction problems in the biological wiring of the heart as well.

Atrial fibrillation, an irregular rhythm that affects the normal pumping of the heart, is a common complication associated with HCM. Patients may also suffer ventricular tachycardia and other serious arrhythmias.

In addition, blood clots may form in the hypertrophic heart, then travel through the bloodstream, causing a stroke, heart attack, or reduced blood flow to the arms and legs.

Symptoms of Hypertrophic Cardiomyopathy

HCM may cause few symptoms, even in those who have had the condition for some time, or it can manifest dramatically, as sudden heart failure. There is a great deal of variation both in the severity of symptoms, and in the progression of the disease.

In the early stages of HCM, individuals may report shortness of breath, chest pain or discomfort, fainting or dizziness, especially upon exertion, and palpitations—a rapid or irregular heartbeat.

Because none of these symptoms is unique to HCM, the condition is often misdiagnosed as exercise-induced asthma, mitral valve prolapse, or anxiety/depression.

Complications of HCM

While HCM involves a structural abnormality in the heart muscle, patients often have conduction problems in the biological wiring of the heart as well.

Atrial fibrillation, an irregular rhythm that affects the normal pumping of the heart, is a common complication associated with HCM. Patients may also suffer ventricular tachycardia and other serious arrhythmias.

In addition, blood clots may form in the hypertrophic heart, then travel through the bloodstream, causing a stroke, heart attack, or reduced blood flow to the arms and legs.

What Causes Cardiomyopathy ?

The causes of primary cardiomyopathy are frequently unknown. Some possible causes in congestive cases are infectious or noninfectious heart muscle inflammation, excessive alcohol consumption, nutritional deficiencies, complications of childbirth, and genetic disorders. Hypertrophic cardiomyopathy appears to be an inherited disease. Restrictive cardiomyopathy is usually caused by a disease called amyloidosis, which is associated with cancers of the blood. Men seem to be affected by congestive cardiomyopathy more often than women. Most cases of cardiomyopathy cannot be prevented. Avoiding smoking and excessive alcohol intake, ensuring proper nutrition, and regular exercise are the only known preventive measures.

How is Cardiomyopathy Diagnosed ?

An extremely common condition, hypertrophic cardiomyopathy (HCM) affects at least 1 in 500 Americans. This condition can be diagnosed at any time from infancy to adulthood.

Cardiomyopathy usually can be diagnosed by characteristic physical findings, electrocardiogram, echocardiogram, and, if doubt still exists, cardiac catheterization and radionuclide angiography. A biopsy of the heart wall tissue may help distinguish between the different types of cardiomyopathy.

Between 30% and 60% of HCM patients are diagnosed after an abnormal EKG or echocardiogram (EP Service). However, HCM often manifests differently in children than adults.

Read more about pediatric HCM here.

The most common time to screen for HCM is during puberty or adolescence. The reason: This condition often manifests during a rapid growth spurt or once the affected individual engages in competitive sports.

HCM accounts for roughly one-third of sudden cardiac deaths among young athletes. Distinguishing between an athletic heart, an HCM heart, and a heart with hypertensive heart disease can be difficult. Therefore patients must be carefully monitored and assessed.

The risk of SCD decreases after adolescence and overall, only one percent of HCM patients succumb to sudden cardiac death. Genetic testing can identify family members who have inherited the gene and thus are at risk for developing HCM. Sometimes the gene can also tell us if patient is likely to develop electrical abnormalities or arrhythmias and can also indicate if a person is at risk for sudden cardiac death. While this risk of SCD is roughly 5% at adolescence, this tapers off with age. Only 1% of all patients with HCM are at risk for SCD.

Dr. Hiroo Takayama - How is hypertrophic cardiomyopathy diagnosed?