LAUSR

The implantation of a biological prosthesis has become nowadays the most common approach to any aortic valve disease requiring valve replacement. Also young and active patients more and more frequently ask for a biological aortic valve substitute, primarily with the aim of avoiding all the drawbacks related to the anticoagulant therapy. The two most desirable characteristics of a good bioprosthesis consist of its extended durability and its adequate hemodynamics. As we shall see, the two features are interdependent. The process of structural valve deterioration (SVD) is related mainly to the patient's immune response to a xenotransplantation, responsible for a progressive leaflets deterioration and eventually severe valve stenosis, incompetence, or mixed lesion. The patient's age is inversely related to the rate of valve degeneration, with recent guidelines limiting the aortic bioprosthetic implantation to patients younger than 50 years. Another relevant, even if controversial, factor promoting earlier SVD after aortic bioprosthetic implantation is the possible occurrence of a patients prosthesis mismatch (PPM), associated with residual elevated transvalvular gradients at rest and under stress. Therefore, particularly in active patients the echocardiographic evaluation under exercise or stress is mandatory. Indeed, it has been demonstrated that a physiologic hemodynamic behavior of a bioprosthesis is closely related to faster LV hypertrophy regression and prolonged valve durability. Several aortic bioprostheses are nowadays available on the market, mostly assembled by using bovine or porcine tissues and realized with stented or stentless design, in addition to the more recently developed bioprostheses, like the sutureless valves and the transcatheter implantable devices. A lot of papers have been published in the literature, reporting mid‐term results after aortic valve replacement by using aortic bioprostheses, sometimes with excellent outcomes. The conclusions of many of these studies are controversial and confounding, and the majority of them refers to experiences with follow‐up times shorter than 10 years. Therefore, a study aiming to clarify and define the SVD factors related to patient and valve and that updates and summarizes the outcomes after aortic valve replacement using the most popular aortic bioprostheses currently in use it is very welcome. Trevor D. Tnay and colleagues from Melbourne, Australia, present in this paper an interesting, updated, and extensive review of the literature concerning the outcomes after bioprosthetic aortic valve replacement, based on a meticulous and accurate PubMed research. The importance of selecting the type of prosthesis according to the patient's age and clinical profile is emphasized, in order to provide an early adequate result and a reduced SVD over time. The most relevant definitions of SVD available in the literature are illustrated and the patient‐related and the valve‐related factors responsible for early and long‐term prosthetic deterioration and failure are highlighted, with particular emphasis on the importance of the increasingly frequent metabolic syndrome affecting patients undergoing aortic valve replacement. Finally, a clinical approach to the clinical evaluation of the patient implanted with a bioprosthesis, as proposed by the VIVID investigators in 2018, is illustrated, and it is summarized in a diagram identifying six stages of SVD, based on clinical and echocardiographic evaluations, at the same time indicating which one is the most appropriate therapeutic decision at each step. Now, assuming the most suitable aortic bioprosthesis for the patient has been selected, in my opinion, the surgical technique and the accuracy of implantation maneuver have a great impact on the early and long‐term outcomes. Prevention of any residual PPM, even moderate, by aortic root enlargement in the cases with small aortic annulus, avoidance of any perivalvular leak, abolition of residual redundant subvalvular outflow