The 'obesity paradox' in patients undergoing transcatheter aortic valve implantation. A specialized narrative review

Obesity has long been identified as a noteworthy risk factor for cardiovascular diseases, including aortic stenosis. Nevertheless, an unexplained phenomenon known as the obesity paradox has arisen in the context of transcatheter aortic valve implantation (TAVI), inquiring conventional beliefs. The obesity paradox refers to better clinical outcomes observed in obese individuals undergoing TAVI. These include reduced all-cause mortality, lower rates of procedural complications, and improved long-term survival rates compared to their lean counterparts. Several theories have been proposed to explain the obesity paradox in TAVI. One of the most popular is the adipose tissue-mediated cardioprotective effect hypothesis. It is known that adipose tissue could offer both protective and harmful effects on the cardiovascular system. These effects can be linked to the adipose tissue's distribution, extension, and intrinsic biological characteristics. Obesity has been associated with adipose tissue malfunction, leading to proinflammatory and deleterious effects on the cardiovascular system. As opposed to what is believed, it is suggested that a healthy obese phenotype might be facilitated by exercise, leading to outstanding cardiovascular benefits. A healthy obese phenotype is also associated with a secretome profile that has unique adipose tissue features like adequate fat storage and formation of lipid droplets, a significant capacity for adipogenesis, minimal extracellular matrix fibrosis, potential for angiogenesis, adipocyte browning, and limited infiltration or activation of macrophages. This article is presented as a specialized narrative review, synthesizing current evidence on the relationship between obesity and outcomes in patients undergoing TAVI.