3.3 Impact of TMVI on LVOT
3D derived LVOT area and dimension were evaluated in 29 patients who
underwent TMVI. The LVOT area at the level of the valve stent distal
edge was newly created after TMVI. As shown in Figure 4,
LVOT dimension from LV long-axis
cut plane was the minimum at the valve stent distal edge, became larger
at the middle portion, and was the largest at the aortic annulus
[valve stent distal edge: 9.2 (5.1-15.3), middle portion: 14.0
(11.9-17.8), aortic annulus: 19.2 (17.6-20.2) mm; P <
0.001], while 3D LVOT area tended to large at the valve stent distal
edge, gradually became smaller, and was the minimum at the aortic
annulus [valve stent distal edge: 7.0 (4.0-11.6), middle portion: 6.0
(4.2-8.1), aortic annulus: 3.9 (3.3-4.5) cm2; P
< 0.001]. Of note, there were 8 patients in whom LVOT area
at the level of the aortic annulus was not the minimum; 5 had the
minimum area at the valve stent distal edge and the others at the middle
portion of the LVOT.
As
shown in Figure 5, pre-procedural LVESV, LVEF, and 3D derived AM angle
were significantly associated with LVOT area at the valve stent distal
edge (LVESV: r = 0.56, P = 0.001; LVEF: r = -0.57, P < 0.001;
AM angle: r = 0.68, P < 0.001). In addition, post-procedural
LVESV, LVEF, and 3D derived AM angle were also associated with that area
(post LVESV: r = 0.49, P = 0.007; post LVEF: r = -0.55, P = 0.002: post
AM angle: r = 0.55, P = 0.003). Importantly, LVOT area at the valve
stent distal edge was significantly smaller in patients with increase in
LVOT gradient compared to those without increase in LVOT gradient (P
< 0.001) (Table 4), and the correlation between the LVOT area
and the ∆PG was strong (Figure 6). Multivariable regression analysis
identified that 3D derived AM angle was independently associated with
LVOT area at the valve stent distal edge (standardized regression
coefficient of 0.40, P = 0.017) while LVESV and LVEF were not.
3.4 Observer variability
and comparison between 3D TEE and cardiac CT
The intraobserver variability and
intraclass correlation for the measurements of 3D AM angle and LVOT area
were 1.5±1.6% and 8.9±7.6% and 0.96 and 0.98, respectively. The
corresponding interobserver variability values were 1.9±1.8% and
9.5±6.9% and 0.94 and 0.96, respectively.
The comparison between 3D TEE and MDCT for the measurement of
pre-procedure AM angle was performed. There was a significant although
modest correlation between the 2 measurements (r = 0.62, P <
0.001), and Bland-Altman showed the systematic difference was 2.4° with
limits of agreement of ±11.7°.