Association of Serum Fetuin-A with Valvular Calcium Concentration in Rheumatic Mitral Valve Disease

Background and aim of the study: Fetuin-A is an acute-phase glycoprotein that inhibits ectopic calcification. The study aim was to assess serum fetuin-A levels in patients with rheumatic mitral valve disease (RMVD), and to evaluate the association of fetuin-A with the extent of mitral valve calcification, determined either echocardiographically or by the measurement of calcium and phosphorus concentrations in the resected valve tissues. Methods: The study group comprised 21 patients (14 females, seven males; mean age 48 +/- 12.4 years) with RMVD, who were scheduled for mitral valve replacement surgery, while 30 age- and gender-matched healthy subjects (17 females, 13 males; mean age 43.6 +/- 11.1 years) served as a control group. Baseline serum fetuin-A levels were measured using ELISA, and high-sensitivity C-reactive protein (hs-CRP) levels using immunonepholometry. A Wilkins score was calculated using transesophageal echocardiography, and the resected valve tissues were analyzed for concentrations of calcium and phosphorus. Results: Serum fetuin-A levels were lower and hs-CRP levels higher in the study group than in controls (300.4 +/- 92.5 mu g/ml versus 352.6 +/- 55.3 mu g/ml, p = 0.028; and 1.9 +/- 1.2 mg/dl versus 0.3 +/- 0.2mg/dl, p <0.0001, respectively). An inverse correlation was found between serum fetuin-A and hs-CRP levels (r = -0.690, p = 0.001). A significant association of either serum fetuin-A or hs-CRP was also found to occur with calcium concentration in the mitral valve tissue ( r= -0.684, p = 0.001, and r = 0.510, p = 0.018, respectively), but not with the Wilkins calcium score. Serum fetuin-A and phosphorus concentrations in the MV tissue were independent predictors of calcium concentration in the MV tissue. Conclusion: Serum fetuin-A, which is significantly decreased in patients with RMVD, is an independent predictor of calcium concentration in the mitral valve tissue.