Evaluation of the Inflammatory Response and Long-term Calcification in Post-operated Aortic Valve Replacement Patients.

Evaluation of the inflammatory response and long-term calcification in post-operated aortic valve replacement patients.

Background

Calcification of the aortic valve affects more than 26% of adult patients over 65 years of age and is the main indication for valve replacement in the United States of America. In Mexico, there is no exact figure for the prevalence and incidence of aortic stenosis. Previous evidence shows that aortic valve calcification is an active biological process, associated with inflammation and increased levels of intracellular adhesion molecule 1 (ICAM-1), pro-inflammatory cytokines such as tumor necrosis factor-alpha (TNF-α), interleukin 6 (IL-6), interleukin 1 (IL-1), interleukin 17 (IL-17), interleukin 18 (IL-18), extracellular matrix proteins (MMP-1), tenascin-C7, osteopontin and bone sialoprotein followed by osteogenic differentiation.

Osteoprotegerin (OPG) / RANK / RANK ligand also plays a regulatory role in bone metabolism; however, in bioprostheses, the role they play in dysfunction does not seem to be clear. They have been found in patients with early coronary atherosclerosis, and a significant increase in endothelial progenitor cells with osteoblasts, osteocalcin (OCN) and phenotype (EPN-OCN) and it has been shown that it is an important prognostic marker in valvular calcification. In the final stage of the disease, expression of TGFβ1 and VAP-1 has been found; both genes are triggers of the calcification process without any association with osteogenic transformation, which is not influenced by statins' use; however, first use alters its expression.

The only actual treatment for severe aortic stenosis is surgical aortic valve replacement (AVR). However, even after the procedure, the inflammatory response persists in almost half of the patients. It has been shown that there is no correlation between age, gender, smoking, ventricular geometry, transvalvular aortic gradient, and the persistence of the inflammatory state after valve replacement. Even more, the materials with which the different types of prostheses are manufactured could induce inflammation per se. Biological prostheses, an incomplete cell removal process and therefore the presence of residual proteins of animal origin, could induce a response of the immune system through the xenoantigen Gal-3-Gal- and its corresponding anti-Gal antibodies that have been associated with valve prosthetic damage. The presence of metallic components such as titanium could act as a trigger for the inflammatory response. As regards the hemodynamic profile of the bioprosthesis, it is unknown whether it is correlated with an inflammatory response. In the manufacturing bioprosthesis at the "Ignacio Chávez" National Institute of Cardiology (INC), an evaluation was carried out in the early, and late post-surgical period, it was shown that the inflammatory response after six months is similar to that produced by mechanical prosthesis.