Panel A shows a cross-section of a normal heart (top) and an endomyocardial biopsy sample from a normal heart (bottom; with hematoxylin and eosin staining) that shows normal histologic characteristics ...

Hypertrophic cardiomyopathy (HCM) is a genetic disease that causes the heart muscle to become thicker, making it harder for the heart to pump blood. It's a condition that affects one in 200–500 people ...