EComment. The current bioprosthesis of choice for aortic valve replacements

Abstract

I read with great interest the paper by Yap et al. regarding the best valve substitute for aortic valve replacement [1]. In their results, they included six randomized controlled trials and nine cohort studies yielding a total of 9880 patients from 1974 to 2006. However, we found two additional relevant articles investigating the long-term durability of pericardial and porcine valves. Brown et al. from the Mayo clinic recently published an interesting article assessing the incidence of early thrombosis in patients with biological valves [2]. The paper was in favour of bovine valves because all patients with early valve thrombosis requiring reoperation were implanted with porcine valves. The calculated incidence of valve thrombosis was 1.26% for the Biocor valve, 0.84% for the Hancock valve and 0.37% for the Mosaic valve. There were no patients with valve thrombosis in the pericardial valve cohort. One possible explanation of this discrepancy is related to the design of the porcine valve stent, which promotes blood stasis between the rail of the stent and the belly of the leaflet. Based on their findings, they recommended the implantation of a mechanical or a pericardial valve, in case of early thrombosis of a porcine valve. Grunkemeier et al. reviewed the long-term durability of the Carpentier-Edwards pericardial and bovine aortic valves in 2955 patients [3]. The likelihood of explantation by 15 years was similar for both valves (7% for the porcine valve and 8% for the pericardial valve). However, the modes of failure were different: structural valve deterioration was seen mainly in the form of a leaflet tear for porcine valves and calcification and fibrosis for pericardial valves. According to the available literature, we concur with the conclusion of Yap et al. that the bovine valve is superior in its haemodynamic profiles and has a lower rate of complications. Another advantage of the pericardial valve is the very low rate of valve thrombosis with only one case report of early bioprosthesis thrombosis in the aortic position [4]. Conflict of interest: none declared