Experience with stentless biological aortic valves

With great interest, I read the article by Schneider et al. [1] regarding a 20-year experience with stentless biological aortic valves. The authors describe a series of 604 patients with the Freestyle prosthesis, who were operated on between 1993 and 2014. In the article, it is unclear how many patients really have a 20-year perspective. Unfortunately, the authors did not mention publications from the biggest Freestyle series in the world [2, 3] with more than 2500 patients receiving isolated aortic valve replacement (AVR) with a Freestyle prosthesis and a 17-year follow-up [4]. In their article, the authors do not describe conclusively how complete the follow-up was regarding survival, reoperation and freedom from structural valve disease. Moreover, it is highly unlikely that a complete follow-up of 604 patients can be done on a single day (25 May 2006). The authors confirm our own experience that good long-term results of the Freestyle prosthesis come at the cost of a slightly higher early mortality compared to other valve types. The authors recommend the Ross procedure as an alternative for patients younger than 40 years: they justify this with the statement that ‘57% (of Freestyle patients) had developed structural valve deterioration (SVD) 15 years after surgery’ and that the Ross procedure ‘showed a cumulative incidence of autograft reoperation at 20 years of 31%’. The authors did not mention that the homograft failures have to be added to the incidence of autograft failures to get the full number of reoperations. As for the patient, the reason for reoperation is negligible, the full amount of reoperations after the Ross procedure should be stated, which is probably at least as high as the incidence or reoperations after AVR with a Freestyle prosthesis.