In this national observational study, we compared outcomes of TS and TA TAVI procedures. Although there was a higher prevalence of moderate post-procedural aortic regurgitation in the TS group, there was no difference in vascular and access site complications, length of stay or early or late mortality. These data confirm that both access sites are reasonable in selected patients at centres with the requisite experience, with consideration of individual patient factors and anatomy being paramount in each institution’s heart team decision algorithm.
Clinical outcomes and complications
In our study, we did not find any differences in the device success rates between the two methods, which confirms the findings from a multicentre trial by Ciuca et al (12). One of the key differences between previous studies and our study was the valve delivery systems used. Trials included in two published meta-analyses (1, 6) almost exclusively used Edwards SAPIEN and Medtronic CoreValve systems. Procedures included in our study used newer, third-generation valves, mostly Edwards SAPIEN 3 and Medtronic Evolut R, which could be contributing to the differences in results. However, this must be interpreteted with caution given that Evolut R was used predominantly for TS and Edwards SAPIEN 3 exclusively for TA approach. This is the most salient point when contextualising our data. The choice of access site and prosthesis is governed by patient factors, such as comorbidities and anatomy, as well as institutional factors, such as device availability and operator experience. Most of the between-group differences here are explained by anatomy (eg. more CABG in TA group due to use of pedicled internal mammary grafts) and prosthesis type (eg. more immediate post-TAVI aortic regurgitation with self-expanding valves).
Moderate aortic regurgitation at the end of the procedure was more prevalent in the TS group than in TA (12.5% vs 2.4% p = 0.025). This is different from previously reported findings by Taramasso et al which demonstrated that no significant differences were observed between TS and TA with regards to postprocedural aortic regurgitation (13). This could be explained by the fact that the majority of TS patients received a self-expandable Medtronic Evolut R valve. Self-expandable devices seem to be associated with higher rates of postprocedural aortic regurgitation than balloon-expandable systems (14). Importantly, we did not have data on subsequent outpatient post-TAVI aortic regurgitation, at which time there may be reduced paravalvular leak as annular sealing improves with expansion of the nitinol Evolut R valve frame.
Another important finding is the lack of difference in permanent pacemaker implantation rates between two access sites. It was previously shown that early pacemaker implantation was more frequent after TS procedures than TA (6). It was also reported that pacemaker implantation rates tend to be higher with Evolut R valves compared with SAPIEN 3 (15).
Vascular access site and access-related complications were not significantly different between two groups. This is in keeping with a recent multicentre study that reported the rate of vascular complications among TS and TA as 10% and 9.9%, respectively (12). Additionally, another meta-analysis showed indirectly that the TS method was associated with a decrease in vascular complications compared with TA (16).
Mortality
The meta-analysis by Chandrasekhar et al (1) and data from the UK TAVI registry (9, 10), both suggest that the TS approach is associated with a lower mortality rate compared with TA. A more recent meta-analysis by Takagi et al (6) also claims that early all-cause mortality is lower in TS than TA groups; however, at mid-term, the mortality was equivalent between TS and TA. Data from the FRANCE-2 TAVI registry (4) seem to be the only source suggesting that the TS approach is associated with increased late mortality. In addition, two Italian studies reported no significant differences in mortality between TS and TA access sites (11, 12). Our results are congruent with these data. It is also important to note that the EuroSCORE was significantly higher in the TA group. However, the EuroSCORE was not developed for risk stratification in TAVI. Interestingly, despite the seemingly more invasive nature of the TA procedure, our data suggest no difference in mortality or length of hospital stay.
As described previously in the methods section, in cases when TF approach was not possible, the TS approach was favoured by the MDTs in our centre, and TA was only chosen in cases when TS was not possible. In spite of this, our results demonstrate that the mortality of the TA approach was equivalent.
Limitations
Our study has several limitations. Most obviously and importantly, this study was a single centre, retrospective observational study with a relatively small sample size. Consequently, there are multiple unmeasured confounders. Most pertinently, as access sites were chosen on a clinical basis, there is inherent selection bias. These data cannot, therefore, be used to infer any causal relationship between access route and clinical outcomes. Rather, they must be interpreted in the context of a single centre – albeit relatively high volume – registry. Our sample size further limits interpretation of the data, since prosthesis models, temporal trends in patient selection (from inoperable to high or intermediate risk) and local accrued experience may play a role in procedural and clinical outcomes. Amongst the measured variables, the most obvious difference is the choice of prosthesis, with the Evolut R being unsuitable for TA delivery. We were not able to collect data on quality of life or symptomatic improvement, which is important as the indication for TAVI is symptom improvement rather than prognosis; indeed the former may be a more relevant consideration than the latter in some patients. Finally, we did not have access to clinical outcome data other than all-cause mortality.