SUBJECTS AND METHODS: Blood samples were obtained from 21 patients with AS, 23 with AR and 29 with MR. The serum levels of aminoterminal propeptide, of type I/III procollagen (PINP/PIIINP), and fibronectin were measured to estimate the synthesis of the extracelluar matrix. The carboxy-terminal telopeptide collagen type I (CITP), matrix metalloproteinase-1 (MMP-1, collagenase) and the tissue inhibitor, metalloproteinase-1 (TIMP-1), were also measured to estimate the collagen degradation and metabolism activities. The left ventricular mass (LVM) was calculated by echocardiography. Of the patients, myocardial tissue was obtained during surgery in 11 with AS, 8 with AR and 13 with MR;the collagen volume fraction (CVF) was calculated using picrosirius red staining.

RESULTS: The LVM was significantly larger in the AS and AR groups compared to the MR group (p<0.001), and the CVF also showed significant differences (13±3% in AS, 10±3% in AR, and 6±3% in MR, p<0.001). The fibronectin level was significantly elevated in the AS and AR groups than the MR group (p<0.001), whereas the CITP and MMP-1 levels were significantly higher in the MR group (p<0.05). The PINP/PIIINP showed no significant difference between the groups (p>0.05), and the biochemical markers were no different between the AS and AR groups (p>0.05). Fibronectin was the only parameter showing a positive correlation with both the CVF (r=0.388, p=0.01) and the left ventricular mass (r=0.278, p=0.02).

CONCLUSION: Different mechanisms for the matrix synthesis and degradation were present for the maintenance of myocardial fibrosis and hypertrophy according to the type of VHD, and fibronectin, a major non-collagenous extracelluar matrix, was proved to be an important factor associated with cardiac hypertrophy and myocardial fibrosis.