Hypertrophic cardiomyopathy – Wikipedia

Hypertrophic cardiomyopathy (HCM) is a condition in which the heart becomes thickened without an obvious cause. The parts of the heart most commonly affected are the interventricular septum and the ventricles. This results in the heart being less able to pump blood effectively and also may cause electrical conduction problems.. People who have HCM may have a range of symptoms.

https://en.wikipedia.org/wiki/Hypertrophic_cardiomyopathy