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Page 6 of 8 Antonazzo et al. Vessel Plus 2020;4:3 I http://dx.doi.org/10.20517/2574-1209.2019.33

of multidimensional appraisal and management of these subjects, while confirming the promising role of
TAVI in comparison to medical therapy, balloon aortic valvuloplasty, and SAVR in elderly patients.

The evolution of TAVI has been momentous, and, since the first pioneering cases, TAVI is challenging the
[6]
role of SAVR even in low-risk patients . These successes depend on major refinements in diagnostic tools
(e.g., CT angiography for precise sizing), patient preparation, device improvements, ancillary management
approaches, and post-procedural management [19-26] . These refinements and the fact that TAVI was initially
validated in trials enrolling mostly high-risk patients with advanced age would suggest that all major
[6]
issues concerning TAVI in the elderly have been solved . This is of course false, and substantial research is
still ongoing on several related topics. For instance, the aspects of cost utility and futility remain actively
debated, as well as all issues pertinent to patient preparation, device selection, predilation vs. postdilation,
embolic protection, and post-procedural antithrombotic therapy [6,11-15,27-30] .

The present umbrella review, albeit limited in comparison to other umbrella reviews authored by our
research group given the limited scope of the available evidence base, highlights the importance of frailty
assessment to predict short-term complications and long-term results of TAVI in the elderly, the emerging
role of cognitive assessment before TAVI and prevention of cognitive decline due to TAVI complications,
and the usefulness of cardiac rehabilitation in all old patients with severe aortic stenosis undergoing TAVI.
Further evidence highlights the importance of assessing in a multidimensional fashion the presence of
comorbidities, nutritional status, grip strength, gait speed, and overall functional status, while confirming
the favorable clinical performance at short- and mid-term follow-up of TAVI, without discounting the
niche role of balloon aortic valvuloplasty in patients at prohibitive risk, and the pivotal function of SAVR
in fit patients.

Limitations of this umbrella review are of course those typical of overviews of reviews, including the risk
[9]
of ecological fallacy . In addition, while studies on TAVI usually enroll mostly patients with advanced age,
only a limited set of systematic reviews explicitly aimed at the topic of TAVI in the elderly. Accordingly,
further reviews are eagerly awaited to more poignantly summarize the evidence base for this important
topic in structural heart disease. Focusing on the definition of elderly, our definition of elderly as aged
≥ 65 years is quite arbitrary, especially in the context of TAVI, which is often performed in much older
subjects [31,32] . However, this remains a common pragmatic definition for many patients, non-specialists, and
[32]
decision-makers . In addition, by default, umbrella reviews have limited room to select primary studies
from included reviews. Similarly, having an unrestrictive approach at TAVI indication (e.g., stenosis,
regurgitation, and valve-in-valve) risks mixing “apples with oranges” and providing overly heterogenous
results. Most importantly, the TAVI landscape continues to change, shifting from prohibitive and high-risk
patients, to subjects at intermediate or low risk. Another crucial evolution has centered on devices, which
evolved from the crude Cribier-Edwards device to current-generation, low-profile and fully repositionable/
[21]
retrievable ones . However, as stated above, by definition, umbrella reviews cannot limit inclusion to
a given group of primary studies. Accordingly, we can only let readers subset the included systematic
reviews/studies according to the specific features they are most interested in, when wishing to apply to
specific patient subgroups the findings of our umbrella review.

In conclusion, the scholarly literature on TAVI continues to accrue, reaffirming the favorable risk-benefit
balance of this breakthrough technology in patients with severe aortic stenosis, including selected low-
risk subjects. Our umbrella review, including eight systematic reviews, 39 primary studies, and 8579
patients, highlights the importance of considering frailty scores, as well as nutrition and functional status,
in addition to established surgical risk scores in elderly patients considered for TAVI to improve risk
prediction, reinforcing the favorable impact of this therapy to improve cognitive function.