Severe aortic valve stenosis is one of the most common cause of mortality in adult patients affected with metabolic syndrome [
1], i.e. a clinical condition characterized from visceral obesity that is traduced into insulin resistance, atherogenic dyslipidemia and proinflammatory state [
2]. It is frequently due to an active process involving several pathways, including lipid infiltration, chronic inflammation, fibrosis formation, osteoblasts activation, and valve mineralization. Other causes are congenital valve defects, systemic inflammatory diseases, and endocarditis [
3]. Prevalence is between 2 and 9% in subjects over 65 years and it increases significantly in forthcoming decades as a consequence of the ageing population and of more accurate diagnostic methods [
4]. Severe aortic stenosis is defined by the presence of maximum aortic velocity ≥ 4 m/s, or aortic valve area ≤ 1.0 cm
2, or by the presence of severe leaflet calcification and severely reduced leaflet opening. Surgical aortic valve replacement is indicated in symptomatic patients with severe high-gradient aortic stenosis, and in asymptomatic ones with severe aortic stenosis and left ventricular ejection fraction < 50% [
5]. Its natural history results in the obstruction of the left ventricular outflow, followed by pressure overload and compensatory hypertrophy of the left ventricle. Excessive hypertrophy may decrease coronary blood flow reserve, increase collagen synthesis, interstitial fibrosis, and myocyte degeneration resulting in ischemic cardiac disease, sudden death and heart failure syndrome. Moreover, these patients have major risk of bleeding due to angiodysplasia, alterated platelets function and low concentration of von Willebrand factor [
3]. High-sensitivity cardiac troponin T (hsTnT) is usefulness for risk stratification of severity and mortality [
6]. However, recently some authors described the role of mast cells in calcified aortic stenosis [
7] and an autoptic study detected these cells in the excised valves of patient undergoing elective aortic valve replacement in comparison with normal aortic valves from five healthy subjects obtained on autopsy served as negative controls [
8]. In light of the above, we studied basal serum tryptase as a new serological prognostic biomarker in aortic valve stenosis. Tryptase is a mast cell serine protease that provides information about mast cell number, distribution, and activation depending on the clinical context [
9]. In some cardiovascular diseases, this enzyme has important implications and represents an index of mast cells’ burden [
10,
11]. In particular, in subjects affected with acute coronary syndrome we found higher basal tryptase values in so defined ‘cardiovascular complex’ patients than in ‘non-complex’ ones [
12]. Moreover, in the same population the basal serum tryptase was significantly correlated to the development of major cardiovascular events’ (MACE) up to 2 years, demonstrating a possible long-term prognostic role of this biomarker [
13].