Selection of Aortic Valve Prostheses: Contemporary Reappraisal of Mechanical Versus Biologic Valve Substitutes

Abstract

Approximately 200 000 patients worldwide undergo aortic valve replacement (AVR) each year.1 The selection of an appropriate valve substitute is often a complex decision influenced by both patient and physician preferences. The basic choices available for surgical AVR include mechanical prosthetic valves (largely bileaflet) and biological (porcine or bovine pericardial). Mechanical valves are characterized by excellent structural durability but require lifelong systemic anticoagulation.2 In contrast, bioprostheses may free patients from valve-related oral anticoagulation, but structural valve failure often necessitates reoperation 10 to 15 years after implantation. Furthermore, degeneration of biological valves occurs more rapidly in younger patients in comparison with those of advanced age.3 Other valve substitutes, such as aortic valve homografts and pulmonary autografts (Ross procedure), are usually reserved for special circumstances such as aortic root reconstruction following infection (homografts) or young patients who have not achieved full somatic growth (pulmonary autografts) because of technical complexity of implantation and inconstant durability. Response by Kaneko et al on p 1380 Current guidelines for selection of valve prostheses based on clinical data, including 2 randomized trials,4–7 recommend use of bioprosthetic valves in patients aged ≥65 years3 because (1) the risk of structural valve degeneration is low in elderly patients, and (2) there are advantages in avoiding systemic anticoagulation in frail patients with additional co morbidities. Much of these data were derived from clinical practice 2 to 3 decades ago, however surgical techniques, valve design, and anticoagulation strategies have all markedly evolved. Despite interim changes in clinical practice and recent clinical outcomes data, many clinicians continue to cite antiquated studies advocating use of biological valves in younger patients (<65 years). The aim of using bioprostheses in adults aged <65 years is to decrease the risk of anticoagulant-related hemorrhagic events and to spare patients lifestyle related …