Stentless aortic bioprostheses: their role in the treatment of aortic endocarditis should not be underestimated

Abstract

We read with great interest the comprehensive review article of Funder [1] on the clinical and experimental data surrounding the use of stentless aortic bioprostheses and fully agree with his conclusions. There is no doubt that they are ideal substitutes in patients with small aortic roots to prevent patient–prosthesis mismatch. In this context, they should be implanted in a ‘fullroot’ type of technique to minimize the postoperative aortic regurgitation that may occur due to distortion of the prosthesis [2] and to facilitate both prosthesis over-sizing and the optimization of haemodynamic results [3]. However, we were surprised that Funder did not comment on the value of stentless valves in the context of aortic endocarditis, particularly in patients with root abscesses and prosthetic valve endocarditis. Homografts have been the gold-standard for valve and root replacement in aortic endocarditis for a long time. Although they result in excellent haemodynamics and a low incidence of re-infection after surgery, the need for homograftrelated reoperation should not be underestimated and has been reported to be around 20% at 2 years, most often due to aortic regurgitation [4]. In addition, in these patients, for whom surgery is most often urgent, availability is limited, leading to delay in treatment. In 2003, Siniawski et al. [5] reported on their results using stentless bioprostheses in the setting of complex aortic endocarditis and made a comparison with their experience using homografts. Early mortality, freedom from re-infection and postoperative haemodynamics were not different between the two groups. However, they saw additional benefits of the stentless prosthesis, in that the surgery itself has a more standardized and therefore possibly easier technique. Moreover, limited availability, which may result in delayed surgery using homografts, is not an issue with stentless bioprostheses. If stentless valves are equivalent early after surgery, the question remains of how they compare with homografts in the longer term? Yacoub et al. [6] recently reported the outcomes of a prospective randomized trial including aortic root replacement using Freestyle stentless bioprostheses (Medtronic Inc., Minneapolis, MN, USA) and homografts. Over a median followup of 7.6 years, a significantly higher freedom from valve dysfunction in the stentless group (86 vs 37%) was noted. Consequently, reoperations due to structural valve degeneration were more common after homograft implantation (0 vs 10%). We conclude therefore, that the early outcome of stentless bioprostheses is comparable with homografts in patients suffering from aortic valve endocarditis. As long-term durability and freedom from reoperation are improved using stentless bioprostheses, and because their availability is not restricted, they are ideal substitutes, particularly in patients with complex aortic valve endocarditis.