The current American Heart Association guidelines recommend mechanical valves for aortic valve replacement (AVR) in patients younger than 60 years, and bioprosthetic valves in patients older than 70 years. Either a bioprosthetic or a mechanical valve is recommended between 60 and 70 years. This grey zone reflects the current trend towards increasing use of bioprostheses in progressively younger patients, and also the complexities and trade-offs of selecting an aortic valve prosthesis in older patients. Patients with mechanical valves require lifelong anticoagulation, and risk of bleeding events increases with advancing age. In contrast, risk of reoperation in patients with bioprosthetic valves increases with time and decreases with advancing age.
Two historic randomised clinical trials compared outcomes after valve replacement with first-generation bioprosthetic and mechanical valves. Although these trials are notable for their prospective, randomised design, their major limitations are that comparisons were made between first-generation valves, and most of the study population in these trials was under 60 years of age. Furthermore, recent innovation in transcatheter aortic valve replacement (TAVR) is applicable to replace deteriorated biological prostheses, which may affect the strategy in case of reoperation for octogenarians and their late survival.