Association of matrix metalloproteinase expression and left ventricular function in idiopathic dilated cardiomyopathy.

Myocardial remodeling is an important predictor for the development of dilated cardiomyopathy (DCM). Matrix metalloproteinases (MMPs) are the family of proteins responsible for extracellular remodeling, and tissue inhibitors of metalloproteinases (TIMPs) tightly control their activity. In the present study, the expression of MMP-2, MMP-9, TIMP-1 and TIMP-2 was determined by immunohistochemistry in right ventricular endomyocardial biopsy samples from 16 patients with idiopathic DCM, and its clinical significance was evaluated by comparison with parameters of cardiac function. To obtain a semi-quantitative assessment of MMP and TIMP expression, the average number of positive cells per high power field was counted. The left ventricular ejection fraction (LVEF) significantly correlated with the expression of both MMP-2 (r=-0.68) and TIMP-2 (r=-0.58). Patients were classified into 2 groups according to the degree of MMP-2 expression: strongly positive and weakly positive. LVEF, left ventricular (LV) end-diastolic pressure, right ventricular end-diastolic pressure, pulmonary capillary wedge pressure and the plasma norepinephrine level were significantly greater in the strongly positive group (p<0.05). In conclusion, the expression of MMPs and TIMPs in the cardiac matrix of patients with idiopathic DCM is closely associated with myocardial remodeling and subsequent deterioration of LV performance. These findings suggest new therapeutic targets for patients with idiopathic DCM.