Cardiomyopathies are diseases that occur in the heart muscle. One of the most common types is hypertrophic cardiomyopathy (HCM), in which the heart muscle thickens and hardens, preventing proper heart function. HCM is usually passed down in families. Although HCM is a common type of cardiomyopathy, it’s underdiagnosed and often misdiagnosed.

Hypertrophic Cardiomyopathy Overview

HCM is a disease that causes the walls of the heart’s left ventricle to hypertrophy (thicken) and stiffen, so the inside of the left ventricle gets smaller. This makes it more difficult for the heart to pump oxygen-rich blood to the rest of the body. HCM is believed to affect about 1 in 500 people in the United States.

HCM is caused by gene mutations (changes) passed down in families and is the most common inherited cardiomyopathy. HCM can cause serious complications, including heart failure, arrhythmia (irregular heartbeat, heart valve disease, stroke, and cardiac arrest.

Symptoms of HCM include:

• Chest pain
• Shortness of breath
• Fatigue
• Dizziness or lightheadedness
• Syncope (fainting)
• Palpitations, faster heartbeat, or a fluttering sensation in the chest
• Irregular heartbeat

Symptoms typically arise during exercise or physical activity, but they can occur at rest in severe cases. Many people with HCM do not experience any symptoms. None of the symptoms of HCM are unique — many heart and lung conditions cause some or all of the same symptoms.

Diagnosing Hypertrophic Cardiomyopathy

HCM can be difficult to diagnose. Many of its features, including left ventricular hypertrophy, are also seen in a variety of medical conditions. This means that HCM might be missed and misdiagnosed as another condition.

Doctors must rule out many other conditions that can cause the same symptoms as HCM and produce similar test results. Diagnosing HCM involves a thorough medical history and physical exam followed by imaging and laboratory tests, including blood tests.

1. Medical History

Your doctor will take a thorough family history to see if other family members have HCM. Because the condition can go undiagnosed, it’s important to discuss other heart problems in family members that could be caused by HCM. These include stroke or heart attack at a young age, arrhythmia, and heart failure, as well as having a heart transplant or getting a pacemaker or implantable cardioverter defibrillator. Your doctor will gather a detailed personal medical history to note all the symptoms you’re experiencing, not just heart and lung symptoms.

2. Physical Exam

A thorough physical exam can reveal signs of HCM and rule out other possible diagnoses. Your doctor or cardiologist will use a stethoscope to listen for irregular heart rhythms and heart murmurs. Heart murmurs are sounds made by heart valves that aren’t functioning properly.

3. Electrocardiogram

An electrocardiogram (ECG or EKG) is a key part of diagnosing any heart problem. An ECG uses wires attached to the chest, arms, and legs to measure electrical activity of the heart. In addition, an ECG can detect arrhythmias and other abnormalities in the heart and even show signs of left ventricular hypertrophy.

Your doctor may want you to do cardiac monitoring from home using a Holter monitor or an event monitor. A Holter monitor takes continuous ECG recordings for one or two days. An event monitor takes ECG recordings when you’re having symptoms and activates the monitor. With both devices, you attach the ECG wires to yourself and carry the device with you wherever you go. Your doctor will tell you how long to carry the device.

4. Imaging

Although a standard chest X-ray can show an enlarged heart, it can’t show whether the heart muscle is thickened. Detailed imaging using echocardiography or MRI is needed to look for any physical abnormalities.

An echocardiogram is an ultrasound that measures the size and thickness of different parts of the heart, shows how the heart valves move, and looks for any abnormalities in blood flow. To see the heart more clearly, your cardiologist may do a transesophageal echocardiogram. This procedure involves placing an ultrasound probe down your throat while you’re under sedation.

Echocardiogram can also be used during a stress test. For a stress test, you might do some exercise, such as walking on a treadmill or riding a bicycle, or you might get an injection of a drug that simulates exercise’s effects on the heart.

One important measurement taken during an echocardiogram is the thickness of the left ventricular wall. HCM is suspected if the wall is at least 13 millimeters thick and is not caused by another condition, such as high blood pressure or aortic valve disease.

Cardiac MRI can also help diagnose HCM. MRI can show the structure of the soft tissue that makes up the heart in greater detail than ultrasound.-

5. Cardiac Catheterization

Cardiac catheterization with angiography can examine blood flow and pressure inside and outside the heart. While you’re under sedation, a long catheter is inserted through the groin or arm and into the heart. Using live X-ray imaging and an injection of contrast dye into the bloodstream, a cardiologist can see blood flowing through the heart and coronary arteries that supply blood to the heart muscle.

6. Blood Tests

Standard blood tests are needed to help diagnose HCM and rule out other diseases. Blood tests for cardiomyopathy are usually done to check iron levels, look for certain proteins that might indicate heart failure, and assess how the kidney, liver, and thyroid are functioning.

Occasionally, genetic testing may be done via a blood sample to identify possible gene mutations known to cause HCM. This can help to pinpoint which gene mutation is causing HCM. Family members may also be tested to determine their risk of developing HCM.

Hypertrophic Cardiomyopathy Misdiagnosis

HCM is easily misdiagnosed because it shares so many features with other diseases that affect the heart or breathing. In its early stages, HCM may not be obvious with imaging, but changes in the heart can still cause symptoms. Some common misdiagnoses include exercise-induced asthma, panic attacks, heart murmurs, and depression.

Many heart conditions can cause arrhythmias, such as atrial fibrillation (AFib). In addition, other conditions that can cause left ventricular hypertrophy may be difficult to tell apart from HCM on imaging scans. These include:

• Hypertension (high blood pressure)
• Genetic disorders, such as Fabry disease, Danon disease, and Pompe disease
• Physiologic hypertrophy, also called athletic hypertrophy or athlete’s heart, a type of left ventricular hypertrophy that occurs as a healthy response to exercise in well-trained athletes
• Aortic valvular stenosis

Proper Diagnosis

It’s important to correctly diagnose HCM to begin appropriate treatment and prevent dangerous complications. A wrong diagnosis can delay proper health care.

Communicating with your health care providers is important to make sure you receive the correct diagnosis and treatment. Be sure to discuss any family history of heart conditions or any symptoms you experience with your doctor.

Talk With Others Who Understand

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