[Grey zones on valvular heart disease: interventional cardiology versus cardiac surgery. Expert opinion].

Clinical guidelines, while representing an objective reference to perform correct therapeutic choices, contain grey zones, where recommendations are not supported by solid evidence. In a conference held in Bergamo in October 2018, an attempt was made to highlight some of the main grey zones in Cardiology and, through a comparison between experts, to draw shared conclusions that can illuminate our clinical practice. This manuscript contains the statements of the symposium concerning the controversies in the percutaneous treatment of valvulopathies. The first topic concerns the durability of aortic bioprostheses, comparing percutaneous interventional with surgical experiences. The second issue examines the opportunity to extend percutaneous aortic replacement as standard care to low-risk patients. The last gap in evidence concerns the percutaneous treatment of functional mitral valve insufficiency, with the MitraClip system. The work has also been implemented with evidences deriving from important randomized studies published after the date of the Conference.