Abnormal heart morphology Myocardial fibrosis HP:0001685 UMLS:C0151654 Myocardial fibrosis is characterized by dysregulated collagen turnover (increased synthesis predominates over unchanged or decreased degradation) and excessive diffuse collagen accumulation in the interstitial and perivascular spaces as well as by phenotypically transformed fibroblasts, termed myofibroblasts. Myocardial fibrosis disrupts the myocardial architecture, contributes to myocardial disarray, and determines mechanical, electrical, and vasomotor dysfunction, thus promoting the progression of cardiac diseases to heart failure.