Signs and Symptoms

Many people with hypertrophic cardiomyopathy (HCM) have no or few symptoms. As a result, the condition may go unnoticed for a while:

• Until a doctor hears a heart murmur during an exam or sees something on a test, most commonly an electrocardiogram, or
• Because a close family member (parent or sibling) is diagnosed with it or known to have died suddenly at a young age.

How someone with HCM might feel varies widely, even among family members. It will depend on several factors. For example, how much thickening there is to the heart muscle, and whether it is slowing or blocking blood flow to the body.

The most common signs and symptoms are:  

• Feeling short of breath, especially when exercising or being active
• Dizziness or fainting
• Chest pain
• Heart palpitations or fluttering of the heart
• Being overly tired or having little energy to do usual activities

In many cases, symptoms may start only with exercise or when exerting oneself. For example, people often notice that an activity they used to do—jogging, hiking, or even climbing stairs—seems more difficult and leaves them short of breath. In some cases, they may even faint.

How does physical activity play a role in triggering symptoms? Normally, with exercise your heart pumps faster and stronger. It gets your blood pumping and improves circulation.

But because a thick heart muscle may already be blocking blood flow to the body, the body’s normal response to exercise can make the blockage worse and further reduce blood flow to the body. Being dehydrated also can make symptoms worse.

Although rare, HCM can cause life-threatening heart rhythms and sudden death if the condition isn’t found or well managed. Other complications can also develop. Early diagnosis and treatment are important.