The role of myocardial fibrillar collagen in ventricular remodeling and function.

The myocardial extracellular matrix (ECM) surrounds and interconnects cardiac myocytes, myofibrils, muscle fibers, and the coronary microcirculation. Because of the high tensile strength of fibrillar collagen and its close association with the functioning components of the myocardium, alterations in interstitial collagen can significantly influence the size and shape of the cardiac chambers as well as ventricular function. Typically, an increase in interstitial collagen concentration secondary to pressure overload results in both the myocardium and the ventricle becoming stiffer. In contrast, a reduction in collagen concentration characterized by a disruption and disappearance of fibrillar collagen leads to a markedly dilated left ventricle that is significantly more compliant. However, the effects of myocardial ECM alterations on systolic function remain to be determined. This article provides a brief summary of the structural and functional consequences of alterations to the myocardial ECM and discusses gaps in our knowledge and future research directions.