In patients with HOCM, the myocardial muscle cells are abnormally thickened related to mutations in the genes encoding contractile proteins in the sarcomere. The myocytes are not able to align properly and the typical description pathologically of heart specimens is that of “myocardial disarray”. Over time, the myocytes are replaced with fibrous tissue which can lead to systolic heart failure or “burnt-out HOCM”.