Patient demographic and clinical characteristics are reported below in Table 1 and CMR measurements are reported in Table 2. The isolated CoA group had higher prevalence of history of hypertension (p=0.03). The majority of BAV patients had right-left leaflet non-separation. Also, CoA+BAV patients had increased CoA severity compared to isolated CoA (moderate or severe CoA in 37% vs 21%, p=0.01) and, overall, very few patients presented with severe aortic stenosis or regurgitation. All groups had normal EF around 65%, and patients with BAV had larger LV volumes and higher LV mass (Table 2). Interestingly, patients with CoA showed higher sphericity index (p=0.02) whilst no group difference was found for arch gothicity or tortuosity (p=0.28 and p=1, respectively).
Three-dimensional templates, calculated for the whole population and the four groups separately, are shown in Figure 3, with atlas error ≤ 0.4mm. As it can be qualitatively appreciated, the template for isolated CoA patients is the shortest and more spherical compared to the others, followed by BAV-CoA and then isolated BAV, compared to the more elongated healthy controls.
Table 1
Patient demographic and clinical characteristics.
|
Isolated CoA (N=25)
|
CoA+BAV (N=30)
|
Isolated BAV (N=30)
|
Controls (N=25)
|
p-values
|
Sex (n, % M)
|
12, 48%
|
16, 53%
|
16, 53%
|
12, 48%
|
p=0.96
|
Age (years)
|
37±12, (19-66)
|
43±8, (31-57)
|
46±14, (20-75)
|
45±11, (27-64)
|
p=0.03
|
BMI (kg/m2)
|
27±6, (20-42)
|
27±5, (17-38)
|
26±5, (17-39)
|
26±4, (21-34)
|
p=0.97
|
Presence of hypertension (n, %)
|
18, 72%
|
11, 37%
|
13, 48%
|
--
|
p=0.03
|
Valve Phenotype (n, %)
|
--
|
RL: 26, 87%
RNC: 3, 10%
LNC: 1, 3%
|
RL: 19, 63%
RNC: 11, 37%
LNC: 0, 0%
|
--
|
|
CoA severity, (n, %)
|
None§: 11, 46%
Mild: 8, 33%
Moderate: 1, 4%
Severe: 4, 17%
|
None§: 12, 40%
Mild: 7, 23%
Moderate: 3, 10%
Severe: 8, 27%
|
--
|
--
|
|
Aortic stenosis severity, (n, %)
|
None: 25, 100%
Mild: 0, 0%
Moderate: 0, 0%
Severe: 0, 0%
|
None: 21, 70%
Mild: 6, 21%
Moderate: 2, 7%
Severe: 1, 3%
|
None: 15, 50%
Mild: 3, 10%
Moderate: 8, 28%
Severe: 4, 14%
|
None: 25, 100%
Mild: 0, 0%
Moderate: 0, 0%
Severe: 0, 0%
|
|
Aortic regurgitation severity, (n, %)
|
None: 22, 88%
Mild: 3, 12%
Moderate: 0, 0%
Severe: 0, 0%
|
None: 14, 47%
Mild: 13, 43%
Moderate: 2, 7%
Severe: 1, 3%
|
None: 7, 24%
Mild: 15, 50%
Moderate: 5, 17%
Severe: 3, 10%
|
None: 25, 100%
Mild: 0, 0%
Moderate: 0, 0%
Severe: 0, 0%
|
|
RL=right-left leaflet non-separation, RNC=right-non coronary leaflet non-separation, LNC=left-non coronary leaflet non-separation, BMI=body mass index. None§ = patients with repaired CoA and no residual narrowing.
Table 2
|
Isolated CoA
|
CoA+BAV
|
Isolated BAV
|
Controls
|
p-values
|
EF%
|
65±8
|
64±5
|
65±8
|
64±4
|
p=0.91
|
EDV (ml/m2)
|
76±19
|
107±48
|
119±48
|
75±10
|
p<0.0001
|
ESV (ml/m2)
|
27±8
|
39±15
|
42±19
|
27±5
|
p<0.0001
|
SV (ml)
|
51±16
|
68±35
|
77±32
|
49±7
|
p<0.001
|
LV mass (g/m2)
|
62±26
|
84±47
|
106±54
|
55±11
|
p<0.001
|
Global Longitudinal Stain
|
-17.1±2.1
|
-17.5±2.0
|
-16.5±2.3
|
-18.2±2.2
|
p=0.02
|
Global Radial Strain
|
35.5±8.2
|
35.7±6.0
|
33.6±8.0
|
37.0±6.2
|
p=0.16
|
Global Circumferential Strain
|
-19.9±2.7
|
-20.1±2.2
|
-19.5±2.4
|
-20.4±1.9
|
p=0.49
|
Apical Radial Strain
|
47.4±14.4
|
38.1±10.5
|
43.9±12.2
|
47.4±12.8
|
p=0.03
|
Apical Circumferential Strain
|
-23.2±3.7
|
-18.3±10.7
|
-21.3±8.2
|
-23.8±3.0
|
p=0.02
|
LV Sphericity Index
|
0.62±0.08
|
0.62±0.08
|
0.59±0.06
|
0.57±0.06
|
p=0.02
|
LV Conicity Index
|
0.52±0.07
|
0.51±0.07
|
0.51±0.06
|
0.47±0.05
|
p=0.05
|
Arch Gothicity
|
1.19±0.17
|
1.28±0.23
|
1.32±0.30
|
--
|
p=0.28
|
Arch Tortuosity
|
0.46±0.07
|
0.46±0.07
|
0.46±0.06
|
--
|
p=1
|
EF=Ejection fraction, EDV=end-diastolic volume, ESV=end-systolic volume, SV=stroke volume.
The first five principal component analysis shape modes (Figure 4) represented 54% of the overall shape variability in the population (Table 3), and hence the corresponding shape vectors were used for statistical analyses. Different modes captured different morphological features, after careful visual assessment and correlation with morphometric measurements (Figure 5). Dominant shape features included: overall LV size (Mode 1), height (Mode 2), sphericity (Mode 3), conicity (Mode 4), and free wall movement (Mode 5). Group differences for shape modes confirmed that the isolated CoA group had the shortest and more spherical LV shape (Mode 2, p=0.01; Mode 3, p<0.001)
Mode 3 correlated inversely with all global strain measurements [i.e. GLS (R=0.20, p=0.04), GRS (R=-0.25, p=0.01) and GCS (R=0.25, p=0.01)], and sphericity correlated with both global and apical radial (R=-0.32, p=0.001; R=-0.41, p<0.0001) and circumferential (R=0.32, p=0.001; R=0.20, p=0.04) strain, overall showing that the more spherical LVs are associated with reduced strain indices. Also, conicity inversely correlated with GRS (R=-0.22, p=0.02) and GCS (R=0.22, p=0.02) (Figure 6). When assessing both sphericity and conicity in a multiple regression model, only sphericity remained significantly associated with both GCS and GRS. GLS correlated with both Mode 2 and Mode 3 (Figure 7), both separately and in a multiple regression(p=0.01), suggesting that there are functional implications of rounder and shorter LVs (as observed in CoA patients).
Table 3
Shape modes (M) with individual and cumulative contribution in LV variation (“Inertia %”). This represents the % shape variability captured by each shape mode individually and cumulatively.
Mode
|
Inertia%
|
Cumulative Inertia%
|
M1
|
14.37
|
14.37
|
M2
|
13.64
|
28.01
|
M3
|
9.83
|
37.84
|
M4
|
8.37
|
46.21
|
M5
|
7.33
|
53.54
|
When assessing the association between sphericity and strain indices in a multiple regression model accounting for the presence of AR and AS, only sphericity was significantly associated with GRS (p=0.01), GCS (p=0.01) and apical radial strain (p<0.0001). When assessing the association between sphericity and strain indices in a multiple regression model accounting for aortic arch gothicity and tortuosity, only sphericity was associated with strain (p=0.05 for GRS; we also noted p=0.06 for GCS).