Diagnosing HCM

Compared to a normal heart and with hypertrophic cardiomyopathy
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.

Because the heart can't fill completely, it can't send enough blood to the rest of the body during exercise

This thickening of the heart muscle can distort the ventricles, affect the function of the mitral valve which also regulates blood flow.

Patients with outflow obstructions can often benefit by interventional procedures or a surgery called septal myectomy that removes the affected muscle and allows the heart to pump more efficiently.
CREDIT: Nancy Heim

Learn more about the diagnosis of HCM from this video.

Hypertrophic Cardiomyopathy (HCM) is a genetically based condition that can be diagnosed at any point in life.

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.

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.

The few patients who progress to end-stage HCM may require a heart transplant or other forms of cardiac replacement therapy such as a ventricular assist device.


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?

Dr. Hiroo Takayama - What are the conditions associated with hypertrophic cardiomyopathy?

Columbia University Medical Center       New York Presbyterian Hospital
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