Association of serum fetuin-A with valvular calcium concentration in rheumatic mitral valve disease

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.

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.

Serum fetuin-A levels were lower and hs-CRP levels higher in the study group than in controls (300.4 +/- 92.5 microg/ml versus 352.6 +/- 55.3 microg/ml, p = 0.028; and 1.9 +/- 1.2 mg/dl versus 0.3 +/- 0.2 mg/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.

Serum fetuin-A, which is significantly decreased in patients with RMVD, is an independent predictor of calcium concentration in the mitral valve tissue.