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Lam et al. Vessel Plus 2019;3:27 I http://dx.doi.org/10.20517/2574-1209.2019.009 Page 7 of 9

and TEE-TAVI groups [7,27] . However, this meta-analysis provides additional insight because it combines
all available studies on this topic, allowing us to increase the sample size and power to examine for any
differences.

Since TTE-TAVI with MAC was associated with shorter hospital LOS and procedure time, TTE-TAVI
with MAC appeared to utilize less hospital resources without any increase in peri-operative morbidity and
[7]
mortality. However, other factors may affect cost of procedure. Hayek et al. found that TTE-TAVI was
associated with significantly higher rates of second valve implantations (odds ratio = 1.58, 95%CI: 1.01 to
2.46), which may negate the beneficial effects of shorter LOS and procedure time on cost. Hence, a more
detailed cost analysis will need to be conducted to determine the economic benefits of anesthesia and
echocardiography type at the time of TAVI.

Limitations
This meta-analysis should be interpreted in the context of its limitations. While this is the largest meta-
analysis to date to compare TTE to TEE for any PVL, we recognize that the sample size is still limited. Thus,
our sample sizes for examining the outcomes of PVL grade may be underpowered to detect differences
in outcomes. Only observational studies were found in the literature after a systematic literature review.
Although there were no significant differences in baseline characteristics, including surgical risk scores,
observational studies inherently include a risk of confounding variables. For example, PVL is influenced
by many factors such as the type of prosthesis used, differences in procedural technique and center
[29]
experience . However, mode of anesthesia is the most concerning confounding variable. We acknowledge
that differences in resource utilization may be the result of using MAC rather than substituting TTE for
TEE alone. It is difficult to separate effects of anesthesia from the type of echocardiography as often the
mode of anesthesia influences the choice of echocardiography performed. Furthermore, this study only
analyzed early outcomes but did not assess late outcomes. Randomized clinical trials are needed to further
investigate differences between TTE and TEE in TAVI.

In summary, the use of TTE-TAVI with MAC does not appear to adversely increase PVL rates compared to
TEE-TAVI with GA. Furthermore, early mortality was similar between the two imaging modalities while
resource utilization appeared to be lower with TTE, although this may have been associated with other
factors such as mode of anesthesia.

DECLARATIONS
Authors’ contributions
Data collection: Lam TK, Dixit AR
Data analysis/interpretation, drafting article: Lam TK
Approval of article: Lam TK, Tam DY, Dixit AR, Fremes SE
Concept/design: Tam DY, Fremes SE
Critical revision of article: Tam DY, Dixit AR, Fremes SE

Availability of data materials
Not applicable.

Financial support and sponsorship
Dr. Derrick Tam is supported by a CIHR Fellowship. Dr. Stephen Fremes is supported in part by the
Bernard S Goldman Chair.

Conflicts of interest
All authors declared that there are no conflicts of interest.