Hypertrophic Cardiomyopathy

Is Testing Right For Me? I Have My Test Results

Hypertrophic Cardiomyopathy

What is Hypertrophic Cardiomyopathy?

Hypertrophic cardiomyopathy (HCM) is a heart condition that causes part of the heart muscle to be thicker than usual. This takes up space in the ventricle — a heart chamber that collects blood and pumps it back out to the body. The thickening may also partially block blood from leaving the heart. These complications may make the heart work harder to pump blood.

People with HCM may have chest pain, dizziness, shortness of breath, fainting, an unusual heartbeat, or no symptoms at all. Rarely, people with HCM can suddenly collapse and die, especially during exercise, without any warning or symptoms. HCM is a common cause of sudden death in young athletes.

HCM is diagnosed by a heart ultrasound, which usually shows "left ventricular hypertrophy" — thickening of the muscle around the left ventricle. Left ventricular hypertrophy has many causes. Heart disease, like high blood pressure or a blood vessel blockage, and some drugs that can damage the heart muscle may cause it. Sometimes left ventricular hypertrophy is just one part of a disease that affects many different organs. In this case, there are usually other signs.

HCM is diagnosed when other causes of left ventricular hypertrophy have been ruled out. It is usually caused by a change in a gene that tells the heart muscle how to work. These gene changes — called mutations — are usually inherited. About 1 in 500 people have HCM.

Many people with HCM need only monitoring, but treatment options are available for those who need them.

Next: Who Is At Risk for Hypertrophic Cardiomyopathy?

Why are you considering genetic testing? Check only one at a time.

I have HCM and no specific cause has been found.

I think I might have HCM, but I haven't had a heart ultrasound yet.

I have a family member who had genetic testing that found an HCM gene mutation.

I have a family history with signs of HCM, but no one has had genetic testing yet.

None of these

Anyone with unexplained HCM should think about genetic testing. Because so many genes cause HCM, your doctor or a genetic counselor should look at your medical history and your family history to see if there are any clues about which genes(s) are most likely to cause your HCM. Otherwise, it may make sense to start by testing some of the most common genes and then test less common genes as needed.

  • When testing finds a mutation, the results confirm that you have inherited HCM. This information can help you and your doctor agree on the best screening and treatment plan for you. Your family members can now have genetic testing for only the one mutation that causes your HCM. This is less expensive and more accurate than complete HCM testing.
  • When testing doesn't find a mutation, the results don't rule out HCM. Genetic testing cannot find all of the mutations that cause HCM. You and your family still need to have early, regular heart screening. The same kind of genetic testing probably won't be useful for your family members.

The symptoms you may feel from HCM are a lot like the symptoms of many different heart conditions. People with symptoms of heart disease may have an electrocardiogram (ECG) to record the rhythm of the heart, an echocardiogram to look at the heart using ultrasound, or other tests.

Genetic testing isn't something to consider until you have been diagnosed with HCM and all the other known causes of it have been ruled out.

Because you have a family member with an HCM mutation, you have a higher chance to have HCM. Your risk depends on how closely related you are to someone with HCM. If you aren't already having regular heart screening based on your family history, talk to your doctor about a screening plan. The only people who can safely avoid early and frequent screening are those who don't have the family mutation. See Screening for Hypertrophic Cardiomyopathy for more information.

Once a mutation that causes HCM has been found in one family member, you and other relatives can have testing for that one mutation. Testing for one mutation is usually much less expensive than complete HCM testing, and the results are more accurate. The laboratory will need to know the exact name of the gene and mutation that runs in the family. If possible, it is best to give the lab a copy of a relative's genetic test results. Parents should consider testing for children by the time they are 12 years old – the age when most experts recommend starting heart screening.

  • When testing finds the mutation that runs in your family, you can be certain that you have inherited the risk to develop HCM. The symptoms of HCM can be very different between people in the same family. So, your results don't necessarily predict your future – but they do mean that you need regular screening to monitor your heart health.
  • When testing doesn't find a mutation, you can be sure that you did not inherit the mutation that runs in your family. As long as the laboratory is sure that the mutation caused HCM in your relative(s) and your heart appears to be healthy, you won't need the extra heart testing usually recommended for people who might have HCM.

You can consider HCM genetic testing, but you may not be the best person in your family to start genetic testing. The first person in the family tested should be someone who has HCM.

Genetic testing cannot find all of the mutations that cause HCM. Testing someone who has HCM first helps find out if genetic testing will be able to find the mutation that causes HCM in your family. It may be possible to do HCM genetic testing on DNA after a person has passed away. If a mutation is found, then all other family members can have testing for the one mutation that runs in the family, which is much less expensive and more accurate than complete gene testing. If a mutation isn't found in someone with signs of HCM, then testing won't be useful for anyone else in the family.

If it isn't possible to test someone with signs of HCM first, you can have testing – but the meaning of your results may not be clear.

  • If testing finds a mutation, then it is likely that you have inherited a risk for HCM. You will need regular screening to monitor your heart health. Testing can also find changes in the gene that haven't been seen before and it isn't clear if they cause HCM. In this case, you should have extra heart screening, but you won't be diagnosed with HCM unless you have symptoms.
  • When testing doesn't find a mutation, there are two possible reasons – you may not have inherited the mutation that causes HCM in your family, or the mutation that causes HCM in your family cannot be found with the test that was done. In this situation, a normal result doesn't change your medical care. You are still at risk for HCM and you need to have regular screening to monitor your heart health.

If you aren't already having regular heart screening based on your family history, talk to your doctor about a screening plan. See Screening for Hypertrophic Cardiomyopathy for more information.

HCM genetic testing probably won't be useful for you if you don't have signs of HCM, and no one in your family does either. If you think you have a reason to consider HCM testing that isn't discussed here, talk to your doctor or a genetic counselor.