Objective: To analyze the influence of recipient-related metabolic factors on the rate of structural dysfunction caused by the calcification of xenoaortic bioprostheses.
Materials and methods: We retrospectively analyzed clinical status, calcium-phosphorus metabolism, and nonspecific markers of inflammatory response in bioprosthetic mitral valve recipients with calcific degeneration confirmed by histological and electron microscopic studies (group 1, n=22), and in those without degeneration (group 2, n=48).
Results: Patients with confirmed calcification of bioprostheses were more likely to have a severe clinical state (functional class IV in 36% in group 1 versus 15% in group 2, P=0.03) and a longer cardiopulmonary bypass period (112.8±18.8 minutes in group 1 versus 97.2±23.6 minutes in group 2, P=0.02) during primary surgery. Patients in group 1 demonstrated moderate hypovitaminosis D (median 34.0, interquartile range [21.0; 49.4] vs 40 [27.2; 54.0] pmol/L, P>0.05), osteoprotegerin deficiency (82.5 [44.2; 115.4] vs 113.5 [65.7; 191.3] pg/mL, P>0.05) and osteopontin deficiency (4.5 [3.3; 7.7] vs 5.2 [4.1; 7.2] ng/mL, P>0.05), and significantly reduced bone-specific alkaline phosphatase isoenzyme (17.1 [12.2; 21.4] vs 22.3 [15.5; 30.5] U/L, P=0.01) and interleukin-8 levels (9.74 [9.19; 10.09] pg/mL vs 13.17 [9.72; 23.1] pg/mL, P=0.045) compared with group 2, with an overall increase in serum levels of proinflammatory markers.
Conclusion: Possible predictors of the rate of calcific degeneration of bioprostheses include the degree of decompensated heart failure, the duration and invasiveness of surgery, and the characteristics of calcium-phosphorus homeostasis in the recipient, defined by bone resorption and local and systemic inflammation. The results confirm the hypothesis that cell-mediated regulation of pathological calcification is caused by dysregulation of metabolic processes, which are in turn controlled by proinflammatory signals.
Keywords: bioprostheses; calcification; calcium–phosphorus metabolism; inflammation.