What Is Hypertrophic Cardiomyopathy?

Hypertrophic cardiomyopathy (HCM) is a form of heart disease that involves thickening (hypertrophy) of the heart muscle, most commonly involving the interventricular septum. The interventricular septum is the heart muscle wall that separates the two ventricles (two lower pumping chambers of the heart).

Heart muscle thickening 
The term “cardiomyopathy” indicates that the increase in muscle thickness is related to a disease of the muscle itself and is not caused by other conditions that are known to make the heart muscle thicken because it is forced to work harder. The thickened heart muscle of HCM is also stiffer than normal and thus does not relax easily to fill with blood between each heartbeat.

  • HCM is the most common genetic disease of the heart (prevalence: 1 in 500).
  • HCM is the most common cause of sudden cardiac death in young people and athletes.
  • HCM is most commonly diagnosed in the second or third decade of life, but may be diagnosed at any age.

Outflow tract obstruction 
In some patients, the muscle is thickened in a critical place that narrows the outflow passage through which blood is pumped out of the heart. This condition is called “outflow tract obstruction.” This creates the murmur (abnormal extra sound made when the heart beats) that is heard in many, but not all, patients with HCM. The abnormally thickened heart muscle is composed of disorganized muscle cells and may also contain scar tissue. The abnormal muscle cells and scar tissue can cause abnormal heart rhythms.

Our board-certified cardiologists and cardiac surgeons utilize a collaborative process to provide progressive strategies to diagnose, treat and stabilize your hypertrophic cardiomyopathy. We strive to return you to normal activities and improve your overall quality of life.

Meet the Hypertrophic Cardiomyopathy Team

Northwestern Medicine Bluhm Cardiovascular Institute is a nationally recognized destination for those who require highly specialized cardiovascular care.

Meet the Northwestern Medicine Hypertrophic Cardiomyopathy Team

Related Resources


Hypertrophic Cardiomyopathy 

External Websites

Hypertrophic Cardiomyopathy Association (HCMA) website : The HCMA is dedicated to improving the lives of those with hypertrophic cardiomyopathy, HCM, preventing untimely deaths and advancing global understanding.