Page 19 - Journal of Structural Heart Disease Volume 5, Issue 3

Original Scientific Article
58
Table 2. CCT and TTE measurements. TTE
Table 3. Factor affecting the difference in AVAs measured by CCT and TTE: simple and multiple linear regression analyses
Measurements
Mean ± SD
Minimum
Maximum
Parameter estimate
Standard error
p-value
AVA (cm2)
LVOT diameter (cm)
LVOT area (cm2)
LVEF (%)
Transaortic mean gradient (mmHg)
CCT
AVA (cm2)
LVOT minimum diame- ter (cm)
LVOT maximum diam- eter (cm)
LVOT area (cm2)
LVOT eccentricity index
0.69 ± 0.16 2.11 ± 0.25 3.52 ± 0.77 51.2 ± 14.3 44.6 ± 14.8
0.91 ± 0.30 2.25 ± 0.27
2.88 ± 0.31
5.0 ± 0.92 0.78 ± 0.07
0.29 0.99 0.13 2.74 1.32 5.9 10 73
18 110
0.38 2.97 1.57 3.20
2.15 3.83
3.24 7.66 0.62 0.98
Simple linear regression analysis
Log10 AVC Agatston score
AVC grade (0/1 vs. 2/3) Transvalvular mean PG
LVOT area difference between CCT and TTE
CCT image quality Age
Annular Ca 4 grade Atrial fibrillation LVOT eccentricity Sex
LVEF
Multiple linear regression analysis
Age
Log10 AVC Agatston score
LVOT area difference between CCT and TTE
Transvalvular mean PG AVC grade (0/1 vs. 2/3) CCT image quality
-0.3095 0.0349
-0.2396 0.0606 -0.1636 0.0545 0.0983 0.0368
-0.195 0.0667 -0.0082 0.0031 -0.0858 0.0572 0.0708 0.0542 -0.2236 0.3863 -0.0262 0.0545 -0.0009 0.0019
-0.0061 0.0024 -0.2670 0.0394
0.0822 0.0291
-0.0286 0.0465 -0.0164 0.0570 -0.1037 0.0553
<0.001
<0.001 0.003 0.009
0.004 0.009 0.136 0.194 0.564 0.632 0.648
0.013 <0.001
0.006
0.539 0.774 0.063
AVA = aortic valve area; TTE = transthoracic echocardiography; CCT = cardiac computed tomography; LVEF = left ventricular ejection fraction; LVOT = left ventricular outflow track; TTE = transthoracic echocardiography
equation-derived AVATTE was significantly smaller than planimetry-derived AVACCT, mainly due to the flow contraction phenomenon observed at the aor- tic valve [9-15]. In our study, 24% (n=31) of patients would be reclassified to moderate AS (n=28) or mild AS (n=1) or no AS (n=2) by AVACCT. Therefore, a simple comparison between these two AVAs will thus be associated with difference and several in- dividual factors have already been associated with this difference [12-15].
Underestimation of AVATTE may lead to discordance in AS severity grading, particularly for those with low mean pressure gradient < 40 mmHg despite small AVA < 1 cm2 [20]. We have noted that most patients (95%) had elliptical shape of LVOT and that LVOT di- ameter measured by TTE was smaller than LVOT min- imum diameter measured by CCT. As a result, TTE sig- nificantly underestimated LVOT area and AVA when compared to CCT. Several studies have demonstrated that noncircular shape (ellipticity) of the LVOT and underestimation of LVOT area results in underesti- mation of the continuity equation-derived AVATTE by
AVA = aortic valve area; AVC = aortic valve calcification; Ca = calcification; CCT = cardiac computed tomography; LVEF = left ventricular ejection fraction; LVOT = left ventricular outflow track; PG = pressure gradient; TTE = transtho- racic echocardiography
two-dimensional echocardiography when compared to three-dimensional echocardiography [21, 22]. We found that the numeric difference between AVACCT and AVATTE was increased with increasing difference in LVOT area between CCT and TTE. However, the CCT measurement of LVOT eccentricity was not associ- ated with difference between AVACCT and AVATTE. In- terestingly, AVACCT was not correlated with AVATTE in group with LVOT eccentricity ≥ 0.78.
Journal of Structural Heart Disease, June 2019
Volume 5, Issue 3:52-61