Cardiomyopathies are diseases that occur in the heart muscle. One of the most common types of cardiomyopathy is hypertrophic cardiomyopathy (HCM), an inherited genetic disease that causes heart muscle to thicken and harden, preventing proper heart function. Although HCM is a common type of cardiomyopathy, it is underdiagnosed and often misdiagnosed.
HCM is a disease that causes the walls of the heart’s left ventricle to grow thicker and stiffen, making the inside of the left ventricle smaller. This prevents the ventricle from filling properly, making it more difficult for the heart to pump oxygen-rich blood to the rest of the body. Per the Cleveland Clinic, HCM is believed to affect approximately 1 in 500 people in the United States.
HCM is caused by inherited gene mutations and is the most common inherited cardiomyopathy. HCM can cause serious complications, including heart failure, irregular heartbeat (arrhythmia), heart valve disease, stroke, and cardiac arrest.
Symptoms of HCM include:
Symptoms typically occur 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.
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HCM can be difficult to diagnose. Many features of HCM, including left ventricular hypertrophy, are also seen in a variety of medical conditions, leading to misdiagnosis.
A careful and correct diagnosis of HCM is extremely important for determining proper treatment. Doctors must rule out the many other conditions that can cause the same symptoms and produce similar test results. Diagnosing HCM involves a thorough medical history and physical exam followed by imaging and laboratory tests.
Your doctor will take a thorough family history to identify if other family members have HCM. Because HCM can go undiagnosed, it is 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, heart failure, heart transplant, and having a pacemaker or implantable cardioverter defibrillator. Your doctor will gather a detailed personal medical history to identify all the symptoms you’re experiencing, not just heart and lung symptoms.
A thorough physical exam can identify signs of HCM and rule out other possible diagnoses. A physical exam for HCM includes using a stethoscope to listen for irregular heart rhythms and heart murmurs. Heart murmurs are sounds made by abnormally functioning heart valves.
An electrocardiogram (EKG) is an essential part of diagnosing any heart problem. An EKG uses wires attached to the chest and limbs to measure the electrical activity of the heart. In addition, an EKG can detect arrhythmias and other electrical conduction abnormalities in the heart and even identify left ventricular hypertrophy.
Your doctor may want you to undergo cardiac monitoring from home using a Holter monitor or an event monitor. A Holter monitor takes continuous EKG recordings for one or two days. An event monitor takes EKG recordings when you activate it because you are having symptoms. Both devices allow you to attach EKG electrodes to yourself and carry a device with you wherever you go for a specified period of time.
Although a standard chest X-ray can identify an enlarged heart, it cannot show whether the heart muscle is thickened. Detailed imaging using echocardiography or MRI is needed to see what physical abnormalities are present.
An echocardiogram is an ultrasound of the heart used to measure the size and thickness of different parts of the heart and observe the motion of the heart valves and any abnormalities in blood flow. A transesophageal echocardiogram may be performed, which involves placing an ultrasound probe down your throat, under sedation, in order to see the heart more clearly.
An echocardiogram can also be used during a stress test, which involves doing exercise, such as walking on a treadmill or riding a bicycle, or having an injection of a drug that simulates the effects of exercise on the heart. One of the important measurements taken during an echocardiogram is the thickness of the left ventricular wall. HCM is suspected if it is at least 13 millimeters thick and 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.
Cardiac catheterization can examine blood flow and pressures inside and outside the heart. While a person is under sedation, a long catheter is inserted through their groin or arm and into their heart. Using live X-ray imaging and an injection of contrast dye into the bloodstream, a cardiologist can see blood flow through the heart and the coronary arteries that supply blood to the heart muscle.
Standard laboratory tests are needed to help diagnose HCM and rule out other diseases. Tests typically include a complete blood count, metabolic panel, heart disease biomarkers, and tests for kidney and liver function.
Occasionally, genetic testing may be performed 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 assess their risk of developing HCM.
HCM is easily misdiagnosed because it shares so many features with other diseases that affect the heart or breathing. In its early stages, changes in the heart due to HCM may not be obvious with imaging, but they 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, or other signs and symptoms that are seen in HCM. Other conditions can cause left ventricular hypertrophy that may be indistinguishable from HCM on imaging scans. These include:
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.
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