Editorial Comment: Re: The worldwide experience with the 29-mm Edwards SAPIEN XTTM transcatheter heart valve in patients with a large aortic annulus

This series chronicles the results of 120 patients receiving the 29-mm Edwards SAPIEN XT™ bioprosthesis over a 15-month period in 20 centres [1]. It is instructive from a number of different standpoints. First, it is apparent from this experience that there are a significant number of patients with aortic annuli between 24 and 27 mm who were previously not able to be treated because of the unavailability of a larger-sized valve. It is also noteworthy that in the whole Prevail TA experience approximately one-third of the patients received the 29-mm valve indicative of the clinical need for the larger sized valve [2]. Second, there is a notably high procedural success rate (95.8%) with remarkably few complications. In point of fact, the 30-day survival of 95.8% and 1-year survival of 79.8% are among the better results reported with transcatheter aortic valve replacement (TAVR). It is, of course, unlikely that these improved results are due to the valve itself, but is in all likelihood multifactorial and encouraging nonetheless. Possible reasons for better results include the fact that the patients are somewhat better-risk patients (Society of Thoracic Surgeons predicted risk of mortality score of 6.8 versus 11.2% in the Partner trial), the implanting centres had gained significant previous experience with the TA approach and perhaps improved 1-year survival due to less paravalvular leak. This is indicative that both procedural and intermediate term results continue to improve with TAVR. Third, and perhaps most important, there is a remarkably low rate of paravalvular leak. Specifically, there were only two patients (2.2%) who had a moderate paravalvular leak and 12.8% with mild aortic regurgitation. This contrasts with a 12.2% incidence of moderate or severe paravalvular leak in the Partner cohort A series in which only 23 or 26 mm valves were available [3]. As annular sizing becomes more sophisticated with the realization that echocardiographic assessment frequently undersizes the aortic annulus and that calculation of true aortic annular size by computed tomography scan leads to greater use of larger diameter valves, it could be anticipated that a significant number of patients currently receiving 26-mm valves may in fact be better treated with 29-mm valves and perhaps have less paravalvular leak and thus improved longterm survival. Fourth, a slight note of caution is warranted, to indicate that there may be a higher permanent pacemaker implantation rate with the 29-mm valve. The pacemaker implantation rate of 12.5% in this series is higher compared with an average 5% pacemaker implantation rate with the 23- and 26-mm Edwards SAPIEN valves. Although this series is small and no conclusions can be definitively drawn, it is possible that the larger valves cause more compression of the membranous septum and therefore a higher permanent pacemaker rate. A larger experience is necessary to determine whether this observation is true. Fifth, despite the use of the larger valves, it is noteworthy that there were minimal procedural complications including no annular disruptions and a stroke rate of 1.7%. This stroke rate is among the lowest reported with TAVR.