Hypertrophic cardiomyopathy (HCM) can be hard to diagnose. Symptoms can vary from person to person and often look like signs of other health problems. Doctors usually need to do several tests to figure out if someone has HCM. These tests help doctors find out what’s causing your symptoms.

Cardiomyopathies are diseases that affect the heart muscle. According to the American Heart Association, one of the most common types is HCM, in which the heart muscle thickens and hardens, preventing the heart from working properly. HCM is usually passed down in families. Although HCM is common, it’s underdiagnosed and often misdiagnosed.

Hypertrophic Cardiomyopathy Overview

HCM 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 harder for the heart to pump oxygen-rich blood to the rest of the body. HCM affects about 1 in 500 people in the United States, but many don’t know they have it.

Hypertrophic cardiomyopathy is believed to affect about 1 in 500 people in the United States.

HCM is the most common inherited heart disease. Untreated HCM can cause serious complications, including heart failure, arrhythmia (irregular heartbeat), heart valve disease, stroke, and cardiac arrest.

Symptoms of HCM may include:

• Chest pain
• Shortness of breath
• Fatigue
• Dizziness or lightheadedness
• Syncope (fainting)
• Palpitations, including a fluttering or irregular heartbeat

Diagnosing Hypertrophic Cardiomyopathy

Diagnosing HCM can take several steps because its symptoms are a lot like those of other health problems. This can make it easy to miss or confuse with another condition.

To find out if someone has HCM, doctors first need to rule out other possible causes. Diagnosing HCM involves a thorough medical history and physical exam, along with imaging and laboratory tests, including blood tests.

Diagnosing HCM involves a thorough medical history and physical exam followed by imaging and laboratory tests.

1. Medical History

Your doctor will take a family history. Because the genetic condition can go undiagnosed, it’s important to discuss any heart problems in family members. These include first-degree relatives who have had a stroke or heart attack at a young age, arrhythmia, or heart failure, as well as family members who have had a heart transplant, a pacemaker, or an implantable cardioverter defibrillator.

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 working 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 the electrical activity of the heart. Although an ECG can’t directly show structural thickening of the heart muscle, it can suggest left ventricular hypertrophy based on certain electrical patterns. Imaging tests, such as an echocardiogram or cardiac MRI, are needed to confirm the diagnosis.

Your doctor might prescribe a Holter monitor or an event monitor to check your heart rhythm while you go about your daily activities. A Holter monitor records your heart’s electrical activity continuously for one or two days. An event monitor records your heart’s activity only when you’re having symptoms and activates during those times. With both devices, you attach the ECG wires to yourself and carry the device with you. Your doctor will tell you how long to use the monitor and will review the results to help make a diagnosis.

4. Imaging

A chest X-ray may show an enlarged heart, but it can’t detect the thickened heart muscle seen in HCM. Detailed echocardiography or MRI scans may be 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.

An 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 confirmed if the wall is at least 15 millimeters thick and the thickening isn't caused by another condition, such as high blood pressure or aortic valve disease. If you have a family history of HCM or positive genetic testing, a wall thickness of 13 millimeters may be enough for a diagnosis. According to the Journal of the American College of Cardiology, your doctor will also consider other factors — including your body size and whether you’re male or female — when interpreting these measurements.

Cardiac MRI can also help diagnose HCM. MRI scans 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

Although they can’t confirm HCM, blood tests help rule out other causes of heart symptoms and check for complications. Doctors might also measure specific substances in the blood — such as NT-proBNP and troponin — which can show if the heart is under stress or has been damaged.

In addition to standard blood tests, genetic testing may be done using a blood sample to look for changes in genes known to cause HCM. Family members may be tested as well to see if they’re at risk.

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.

HCM is easily misdiagnosed because it shares features with other diseases that affect the heart or breathing. Common misdiagnoses include exercise-induced asthma, panic attacks, heart murmurs, and depression.

Many heart conditions can cause arrhythmias, such as atrial fibrillation. 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 complications. A wrong diagnosis can delay getting the care you need.

Talking openly with your doctor helps you get the right diagnosis and treatment. Make sure to mention any heart problems in your family and symptoms you’ve had. Sharing this information gives your doctor a clearer picture of your health and can help guide the best care plan for you.

Talk With Others Who Understand

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