VALUES OF OSTEOPROTEGERIN IN AORTIC VALVE TISSUE DIFFER SIGNIFICANTLY BETWEEN CALCIFIED AORTIC VALVE STENOSIS AND NORMAL AORTIC VALVE AND ARE SIGNIFICANTLY INFLUENCED BY THE PRESENCE OF CONCOMITANT CORONARY ATHEROSCLEROSIS

Background: The load of calcium in aortic valve is the most significant predictor of clinical progression of calcified aortic stenosis (CAS). Osteoprotegerin (OPG) was identified as a key regulator in vascular calcification.
Aim: The purpose of study was to determine concentrations of OPG in aortic valve tissue in patients with symptomatic CAS without (Group A) and with concomitant coronary atherosclerosis (Group B), and in normal aortic valves. (Group C).
Methods: Tissue samples were collected at surgery from patients undergoing AVR (N - 44, 69.0±10.7 yers, 57% male), AVR + CABG (N - 61, 73.4±8.3 years, 64%men). Normal aortic valve tissues were obtained from explanted hearts during transplantation (N - 21, 49.6±13.7 years, 81% male). The frozen tissue was powdered by grinding in a pre-chilled abrasive material. Once the tissue was ground to a fine powder, the extraction solution was added and further incubated at room temperature for 1 hour. Mixture was analyzed by ELISA method.
Results: The highest tissue concentration of OPG [pmol/l] (median, 25th to 75Th percentile) was found in Group A (6.95 (3.96-18.37)). The lowest was the concentration in normal aortic valve tissue (2.25 (1.01-5.08)). After adjustment for age and sex the difference in tissue OPG between group A and C was highly significant (p=0.001). Levels of OPG in Group B (4.15 (2.47-9.16)) were significantly lower in comparison to group A (p after adjustment = 0.025). The difference between group B and C did not reach significance (p=0.078). Conclusion: The significant difference in tissue concentrations of OPG was found between patients with symptomatic CAS and normal human aortic valves. The highest tissue OPG was found in patients with CAS and without concomitant coronary atherosclerosis