New strategies are needed to early detect myocardial involvement in these diseases. Histological studies showed that diffuse fibrosis and cardiomyocyte hypertrophy precede the LV remodelling (dilatation) observed by cardiac imaging. Quantification of LV diffuse myocardial fibrosis using magnetic resonance imaging (MRI) could reach this goal. Recently, contrast enhanced cardiac MRI has been used to measure the extracellular volume fraction (ECV) of the myocardium, and it has been able to detect diffuse myocardial fibrosis. In diseases in which increased collagen deposition enlarges the extra-cellular space, the ECV can act as a fibrosis index. ECV is correlated with the amount of fibrosis measured by histology. Left ventricular overloads induced by regurgitant VHD result in cardiomyocyte hypertrophy and diffuse fibrosis. Other methods can be used to estimate the degree of myocardial fibrosis such as the serum level of galectine-3 or ST2. Moreover, although the pathophysiological mechanisms leading to the occurrence of myocardial fibrosis differ in patients with various cardiac diseases, the cellular effectors of fibrotic remodelling are common and involve similar signalling pathways. At the cellular level, key progression of ventricular hypertrophy is associated with increased cardiomyocytes apoptosis and fibrosis, suggesting that these two processes are responsible for the transition.