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As the experience with transcatheter aortic valve implantation (TAVI) grows, expanded use in new patient populations and for novel indications can be anticipated. There are however, many as yet unsolved clinical issues that need to be addressed before unbridled, expanded application into lower risk patients is warranted. For example, paravalvular leak occurs to some degree in the majority of patients receiving a transcatheter aortic valve. There is increasing evidence that even mild paravalvular leak is associated with increased mortality at 2 years.1 As indications for TAVI expand to younger and lower risk patients with a longer life expectancy, this issue will carry greater importance. Similarly, valve durability has hitherto not been an issue of significant clinical consequence. The long term durability of catheter delivered valves is as yet unknown. With TAVI use in populations with longer life expectancy post implant, this issue will also carry greater importance.
In this article, we will first discuss some of the unsolved technical and clinical issues with TAVI and update the progress that has been made in addressing them. We will then discuss expanded and novel indications including TAVI in lower risk patients, patients with previously implanted surgical bioprostheses and in those patients with concomitant coronary artery disease. Lastly, we will survey the landscape of next generation valves and the novel ancillary technology that is being developed to both facilitate the procedure as well as address some of the current shortcomings. This technology includes access devices for both transfemoral and transapical approaches, cerebral protection devices, and measures to minimise paravalvular leak.
Unsolved technical and clinical issues
Placement of a second or on rare occasions even a third transcatheter valve at the time of initial implant is a relatively unusual event, occurring in 38 of 2208 (1.8%) of patients in a recently reported meta-analysis.2 The usual indications for TAVI-in-TAVI …