What we see depends on what we look for.

With great interest we read the meta-analysis on mortality rates after transcatheter aortic valve implantation (TAVI) and surgical aortic valve replacement (SAVR) by Barili et al. [1]. The results presented are of great importance and provide a shadow of doubt on the current enthusiasm on TAVI.

Implementation of new technology is risky business as the use of new devices might be related to complications not previously seen with the procedure considered as gold standard. An interesting observation can be made when the recently published 5-year results of the PARTNER 2A trial are studied in detail [2]. Prosthetic aortic valve performance after TAVI seems non-inferior to SAVR. However, treatment should not only focus on the resolution of the primary abnormality itself but also on the resolution of the consequences thereof. As a result of higher outflow gradient seen in aortic valve stenosis, compensatory changes in left ventricular volumes (higher end-systolic and end-diastolic volume) and mass will occur. Successful resolution of aortic valve dysfunction should thus also result in normalization of left ventricular volumes as well as mass regression. The results provided by the PARTNER 2A trial, however, show that TAVI was inferior in stimulating volume and mass regression when compared to SAVR. These results suggest that while the aortic valve is effectively treated with TAVI, SAVR is more effective at treating the disease as a whole. Whether this is a consequence of higher rates of paravalvular leakage or other complications more often seen with TAVI (e.g. intraventricular conduction abnormalities) warrants further study. No matter the underlying cause, late results should in theory be in favour of SAVR, as excellently shown by Barili et al.

As a last thought, it should be acknowledged that the performance of TAVI prostheses has improved and that the results of TAVI are far more dependent on the type of prosthesis implanted than the results of SAVR. The study by Barili et al. presents the best data on the performance of this technology but is clearly limited by the drawbacks of the available literature. At this point, the level of evidence cannot be considered sufficient to support changes in the way the majority of patients with aortic valve stenosis should be treated.