4.6 Study limitations
Data for this study were collected retrospectively from single center
database.
Accordingly,
our study included some limitations.
First, there were the numerous
factors influencing our results such as the sample size as well as the
risk for selection bias and the observer bias.
Our study sample size was small,
especially patients who had significant increase in LVOT gradient after
the TMVI, leading to the statistical limitation to examine the impact of
variables on LVOT narrowing. In
addition, the population was very heterogeneous in terms of TMVI
settings (ViV, ViR, and ViN).
Further,
the measurer could not measure all the parameters blindly because the
measurer knew that a prosthetic valve was placed. Second, the current
study evaluated the LVOT narrowing after the balloon-expandable
transcatheter aortic valves implantation in the mitral position. The
data would differ if a different transcatheter mitral valve was used.