Types of Hypertrophic Cardiomyopathy: A Cardiologist Explains

Hypertrophic cardiomyopathy (HCM) may not be a name that many people are familiar with, but they have likely seen news stories about it. HCM is one of the most common causes of sudden cardiac arrest among young athletes. 

The two types of hypertrophic cardiomyopathy can have different effects on the body, but detection and treatment can help reduce the risk of sudden cardiac arrest and other complications.

What is hypertrophic cardiomyopathy?

HCM is a genetic condition, which means you inherit it from your parents. This condition causes muscle tissue in the heart to become abnormally thick. (Hypertrophy refers to an abnormal thickening, and cardiomyopathy refers to an abnormality of the heart muscle.)

The abnormal thickening generally occurs in the wall of the left ventricle. This is the last chamber blood goes through before leaving the heart and dispersing to other parts of the body. 

What are the types of hypertrophic cardiomyopathy?

Doctors separate HCM into two categories:

• Obstructive hypertrophic cardiomyopathy

• Non-obstructive hypertrophic cardiomyopathy

Obstructive HCM means the heart tissue is so thick that it’s blocking blood flow. The blockage prevents blood from leaving the heart chamber. People with obstructive HCM are more likely to experience symptoms due to the blockage.

Non-obstructive HCM means the heart is thickened, but it’s not blocking blood flow inside the heart. This can still affect blood flow because it means the heart chamber can hold less blood at a time. When there’s less blood in the heart chamber, less blood is pumped out with each heartbeat. 

What are the symptoms of hypertrophic cardiomyopathy? 

Not everyone with HCM has symptoms. For those who do, they may start at any age. Some people may develop symptoms later in life after going many years without them.

Common symptoms of HCM include:

• Shortness of breath

• Reduced stamina

• Chest pain or pressure

• Fluttering heart (arrhythmias)

• Racing heart (tachycardia)

• Dizziness

• Lightheadedness

• Fainting

Arrhythmias are one of the biggest risk factors for sudden cardiac death from HCM.

Why is screening for HCM important?

Because not everyone with HCM has symptoms, screening plays a big role in diagnosing this heart condition. Early detection can help people get access to treatment, which may reduce the risk of complications. This includes cardiac arrest, which can be fatal.

Experts recommend screening for HCM for people who have a family history of the condition. If you have one of the types of hypertrophic cardiomyopathy, you should tell your family members. They may have the condition, too, and should seek screening themselves.