Presence of adipose tissue in aortic valves from aortic regurgitation patients: pathophysiological role and clinical implications

Introduction Adipose tissue is a common constituent of the heart and it is located, without great clinical relevance, frequently in the pericardium. The presence of adipose tissue in the aortic valve is rare, with unknown significance on valve structural properties and function. Aortic regurgitation (AR) is the third most prevalent valve disease, although it is uncommon to find it in isolation. Myxoid degeneration may be the cause or result of AR, although the pathophysiology remains poorly understood. Purpose To describe and characterize the presence of adipose tissue in the aortic valves from a cohort of AR patients. Methods 116 patients undergoing aortic valve replacement due to severe AR were enrolled. We classified them in two groups according to the histological results showing presence or absence of adipose tissue in the aortic valves. In the valve tissue molecular analysis were performed by RT-PCR, Western Blot and ELISA to analyze markers of adipocytes (leptin, adiponectin, resistin), inflammation (Rantes, interleukin-6, interleukin-1β), extracellular matrix remodeling (metalloproteinases-1, -2 and -9), proteoglycans (aggrecan, hyaluronan, lumican, syndecan-1, decorin) and fibrosis (collagens, fibronectin). Results Adipose tissue was found in 63% of the aortic valves analyzed. Baseline characteristics (age, hypertension, dyslipidemia, diabetes, smoking, left ventricular telediastolic diameter, left ventricular systolic function, ascending aorta) were similar in patients presenting valve adipose tissue as compared with patients without valve adipose tissue. Valves containing adipocytes exhibited a higher leptin content (p<0.001), fibronectin (p<0.01), decorin (p<0,0001), hyaluronan (p=0.03), aggrecan (p=0.04) and metalloproteinase 1 (p=0.03). Interestingly, the presence of adipocytes in the valve was positively correlated with valve thickness measured by echocardiogram (Pearson chi2 statistical significance = 26.3345 p<0.001). Conclusion To our knowledge, this is the first study that describes the presence of adipose cells in aortic valves from a cohort of AR patients. Aortic valves containing adipocytes were thicker and exhibited significant higher levels of proteoglycans, suggesting that adipocytes could contribute to the myxomatous degeneration process. Our results propose that the valve adipose tissue could play a role in the pathophysiology of AR. Funding Acknowledgement Type of funding source: Public hospital(s). Main funding source(s): Gobierno de Navarra