3.1 Baseline characteristics
We enrolled a total of 126 subjects (65 males and 61 females, mean age 55 years, range 47–77 years) with normal chamber dimensions and 118 subjects (61 men and 57 women, mean age 54 years, range 30–77 years) with normal wall thickness, 11 patients( 6 men and 5 women, mean age 58 years, range 55–74 years) with LA enlargement. Table 1 shows the clinical characteristics of the study population.
Table 1
General clinical characteristics
Characteristics
|
NCD group
(N = 126)
|
NWT group
(N = 118)
|
LAE group
(N=11)
|
Age(years)
|
55.52 ± 11.38
|
54.89 ± 11.18
|
64.5 ± 7.74
|
Sex(male;n,%)
|
65(51.6%)
|
61(51.7%)
|
6(54.5%)
|
BMI (kg/m2)
|
23.95 ± 2.68
|
24.17 ± 2.70
|
23.63 ± 2.29
|
BSA(㎡)
|
1.65 ± 0.16
|
1.65 ± 0.15
|
1.67 ± 0.17
|
Smoking(n,%)
|
30(23.8%)
|
29(24.6%)
|
2(18.2%)
|
Drinking(n,%)
|
22(17.5%)
|
21(17.8%)
|
1(9%)
|
Hypertension(n,%)
|
34(27.0%)
|
30(25.4%)
|
5(45.5%)
|
Hyperglycemia(n,%)
|
15(11.9%)
|
15(12.7%)
|
1(9%)
|
Hyperlipemia(n,%)
|
32(25.4%)
|
31(26.3%)
|
3(27.3%)
|
HR(Beats/min)
|
62.98 ± 8.67
|
62.98 ± 8.72
|
64.64 ± 20.5
|
LVMM(g)
|
111.07 ± 26.75
|
110.39 ± 24.09
|
117.34 ± 33.14
|
BMI indicates body mass index; BSA,body surface area;HR,heart rates; LVMM,LV-myocardial mass; NCD,normal chamber dimensions; NWT,normal wall thickness |
3.2 LA parameters in different cardiac cycles
Table 2 list the mean ± sd of LA-A, LA-B, and LAVR in different cardiac phases, Fig. 2A shows the change trends. For LA-A, LA-B, and LAVR, the maximum and minimum values were observed in the 35–45% phase and 5% phase, respectively. The maximum values of LA-A and LA-B were 67.03 ± 5.39 mm and 37.70 ± 4.40 mm respectively. The minimum value of LA-B was 29.54 ± 4.43 mm. The variation of LA-B in cardiac cycles was of statistical significance, LA-A and LAVR were not. Compared with LA-A, LA-B changes more stably during the cardiac cycle.
Table 2
Cardiac chamber dimensions in different cardiac cycles
Phase
|
LA-A
|
LA-B
|
LAVR
|
LV-D1
|
LV-D2
|
LV-D3
|
RA-A
|
RA-B
|
RV-D1
|
RV-D2
|
RV-D3
|
5%
|
54.26 ± 6.28
|
29.54 ± 4.43
|
1.77 ± 0.24
|
45.09 ± 4.16
|
50.44 ± 4.73
|
77.36 ± 8.36
|
39.46 ± 5.72
|
36.95 ± 4.84
|
42.13 ± 5.19
|
31.28 ± 5.19
|
74.35 ± 7.96
|
15%
|
56.24 ± 5.90
|
30.71 ± 4.69
|
1.84 ± 0.24
|
43.80 ± 4.69
|
45.99 ± 6.16
|
74.75 ± 7.04
|
42.24 ± 5.51
|
40.55 ± 5.29
|
41.70 ± 5.24
|
29.68 ± 4.95
|
71.06 ± 7.26
|
25%
|
61.49 ± 5.65
|
33.71 ± 4.52
|
1.90 ± 0.30
|
41.06 ± 4.67
|
37.98 ± 6.69
|
66.57 ± 7.47
|
44.55 ± 5.50
|
45.24 ± 5.45
|
38.60 ± 4.97
|
25.90 ± 4.87
|
65.21 ± 7.32
|
35%
|
65.74 ± 5.60
|
36.52 ± 4.44
|
1.92 ± 0.29
|
38.64 ± 4.85
|
30.89 ± 7.23
|
58.94 ± 8.38
|
45.37 ± 5.50
|
48.62 ± 5.27
|
36.13 ± 5.35
|
23.17 ± 4.99
|
60.11 ± 7.55
|
45%
|
67.03 ± 5.39
|
37.70 ± 4.40
|
1.91 ± 0.29
|
37.55 ± 5.43
|
31.15 ± 7.97
|
58.77 ± 8.36
|
45.58 ± 5.18
|
49.68 ± 5.26
|
36.00 ± 5.89
|
23.44 ± 5.40
|
58.63 ± 7.33
|
55%
|
63.99 ± 6.22
|
35.51 ± 5.07
|
1.90 ± 0.29
|
40.16 ± 5.57
|
39.88 ± 8.05
|
66.16 ± 9.53
|
44.90 ± 5.68
|
45.27 ± 5.77
|
39.07 ± 6.18
|
27.22 ± 5.85
|
63.02 ± 8.29
|
65%
|
61.22 ± 5.91
|
33.91 ± 4.65
|
1.88 ± 0.28
|
41.84 ± 4.47
|
44.56 ± 6.10
|
70.55 ± 7.51
|
45.01 ± 5.22
|
42.62 ± 5.25
|
41.15 ± 6.11
|
29.36 ± 6.04
|
65.92 ± 8.14
|
75%
|
60.52 ± 5.66
|
33.94 ± 4.33
|
1.85 ± 0.26
|
42.62 ± 4.17
|
45.42 ± 6.34
|
71.59 ± 7.39
|
44.56 ± 5.47
|
41.96 ± 4.84
|
41.20 ± 5.92
|
29.92 ± 5.96
|
67.28 ± 7.69
|
85%
|
59.69 ± 5.93
|
33.97 ± 4.22
|
1.82 ± 0.26
|
43.40 ± 4.19
|
46.56 ± 5.71
|
72.86 ± 7.10
|
43.76 ± 5.48
|
41.00 ± 4.83
|
41.40 ± 5.79
|
30.22 ± 5.71
|
68.54 ± 7.81
|
95%
|
55.62 ± 6.07
|
31.53 ± 4.75
|
1.80 ± 0.38
|
44.91 ± 4.07
|
49.66 ± 5.17
|
76.37 ± 7.25
|
39.44 ± 5.45
|
36.77 ± 5.02
|
41.95 ± 5.56
|
31.83 ± 5.69
|
73.50 ± 8.22
|
t
|
1.858
|
6.601
|
-0.317
|
2.938
|
6.699
|
3.700
|
1.624
|
-4.603
|
4.885
|
7.889
|
0.669
|
p-value
|
0.063
|
< 0.001
|
0.752
|
0.003
|
< 0.001
|
< 0.001
|
0.105
|
< 0.001
|
< 0.001
|
< 0.001
|
0.504
|
The parameters were expressed as mean values ± standard deviations. LA-A—left atrial maximum transverse diameter; LA-B—left atrial antero-posterior diameter; LAVR—left atrial-vertebral ratio; LV-D1—Left ventricular basal dimension; LV-D2—left ventricular mid cavity dimension; LV-D3—left ventricular apical-basal dimension; RA-A—right atrial major dimension; RA-B—right atrial minor dimension; RV-D1—right ventricular basal dimension; RV-D2—right ventricular mid cavity dimension; RV-D3—right ventricular apical-basal dimension |
In phase 45%, the cut-off value of LA-A was 77.57mm with 36.4% sensitivity, 97.6% specificity, 57.1% positive prediction value, 94.6% negative prediction value. The cut-off value of LA-B was 37.12mm with 90.9% sensitivity, 37.6% specificity, 13.2% positive prediction value, 98.4% negative prediction value. And the combined diagnosis of LA-A and LA-B had 45.5% sensitivity, 98.4% specificity, 71.4% positive prediction value, 95.4% negative prediction value. Besides, LAVR had 1.845 cut-off value with 81.8% sensitivity, 52.4% specificity, 13% positive prediction value, 97.1% negative prediction value.
3.3 LV parameters in different cardiac cycles
Table 2 list the mean ± sd of LV chamber dimensions (LVD1, LVD2, LVD3) in different cardiac phases, Fig. 2A shows the change trends. The maximum and minimum values of LV dimensions were observed in the 5% phase and 35–45% phase, respectively. The maximum values of LV-D1, LV-D2, and LV-D3 were 45.09 ± 4.16 mm, 50.44 ± 4.73 mm, and 77.36 ± 8.36 mm, respectively. The variation of LV-D1, LV-D2, and LV-D3 in cardiac cycles was of statistical significance. Of these diameters, LV-D1 showed the most stable changes during the cardiac cycle.
Results from univariate analysis revealed that body surface area (BSA), heart rate (HR), LV-myocardial mass (LVMM), smoking, and diabetes were significantly related to LV-D2 and LV-D3 (Table 3). Multivariate analysis demonstrated that HR and smoking were potential indicators of LV-D2, and that HR and LVMM were potential indicators of LV-D3. One unit change in HR was associated with 0.187 unit decrease in the LV-D2. The average LV-D2 of smokers is 2.830 mm higher than that of non-smokers. The other variables were not significantly related to LV-D2. One unit change in HR was associated with 0.164 unit decease in the LV-D3, while one unit change in LVMM was associated with 0.124 unit increase in the LV-D3.
Table 3
the univariate analysis of potential related factors for LVD2 and LVD3
Characteristics
|
LV-D2
|
t
|
p-value
|
LVD3
|
t
|
p-value
|
Age
|
0.021
|
0.482
|
0.631
|
-0.175
|
-3.256
|
0.001
|
BMI
|
0.149
|
0.804
|
0.423
|
-0.082
|
-0.346
|
0.730
|
BSA
|
8.500
|
2.750
|
0.007
|
14.096
|
3.642
|
< 0.001
|
HR
|
-0.222
|
-4.130
|
< 0.001
|
-0.231
|
-3.288
|
0.001
|
LVMM
|
0.058
|
3.242
|
0.002
|
0.140
|
6.965
|
< 0.001
|
Smoker
No
Yes
|
41.29 ± 9.30
45.34 ± 8.63
|
3.631
|
< 0.001
|
68.58 ± 10.16
72.00 ± 9.37
|
2.352
|
0.020
|
Drinker
No
Yes
|
41.96 ± 9.03
43.63 ± 10.44
|
1.231
|
0.221
|
68.87 ± 10.16
71.88 ± 9.28
|
1.838
|
0.068
|
Hypertension
No
Yes
|
42.14 ± 9.43
42.56 ± 8.98
|
0.402
|
0.688
|
69.47 ± 10.42
69.19 ± 9.11
|
-0.175
|
0.861
|
Diabetes
No
Yes
|
42.62 ± 9.34
39.52 ± 8.62
|
-2.040
|
0.044
|
69.68 ± 10.15
67.28 ± 9.29
|
-1.231
|
0.221
|
Dyslipidemia
No
Yes
|
41.88 ± 9.28
43.37 ± 9.30
|
1.315
|
0.191
|
69.34 ± 10.15
69.56 ± 9.87
|
0.156
|
0.876
|
Abbreviations as in Table 1 |
Table 4 lists the mean ± sd of LV wall thickness at the basal, mid, and apical segments in different cardiac phases. Figure 2B-C shows the change trend graph of LV wall thickness. The LV wall thickness achieved the minimum at the phase of 95–5%, and the maximum at 35–45%. The maximum values of the interventricular septum (Septum), anterior (Ant), antero-lateral (Ant-Lat), infero-lateral (Post-Lat), and inferior (Inf) at the basal segment were 10.80 ± 1.47 mm, 11.82 ± 2.46 mm, 11.87 ± 2.49 mm, 12.03 ± 2.32 mm, and 10.75 ± 2.10 mm, respectively. The variation of Ant and Ant-Lat in cardiac cycles were of statistical significance. The maximum values of Septum, Ant, Ant-Lat, Post-Lat, and inferior Inf at the mid segment were 11.15 ± 1.98 mm, 10.22 ± 2.53 mm, 10.75 ± 2.88 mm, 10.93 ± 2.56 mm, and 11.89 ± 2.39 mm, respectively. The variation of Septum, Ant, Ant-Lat, Post-Lat, Inf in cardiac cycles was of statistical significance. The maximum values of Septum, Ant, Ant-Lat, and Inf at the apical segment were 9.42 ± 2.19 mm, 10.83 ± 2.31 mm, 10.60 ± 2.14 mm, and 9.15 ± 2.03 mm, respectively. The variation of Septum, Ant, Ant-Lat, and Inf in the cardiac cycles were of statistical significance. In the three segments, the wall changes of the basal segment were the more stable than middle and apical segments.
Table 4
Left ventricular wall thickness in different cardiac cycles
|
Basal
|
Mid
|
Apical
|
Phase
|
Septum
|
Ant
|
Ant-Lat
|
Post-Lat
|
Inf
|
Septum
|
Ant
|
Ant-Lat
|
Post-Lat
|
Inf
|
Septum
|
Ant
|
Ant-Lat
|
Inf
|
5%
|
7.76 ± 1.09
|
7.04 ± 1.30
|
7.38 ± 1.12
|
7.55 ± 1.19
|
7.52 ± 1.31
|
7.93 ± 1.59
|
6.08 ± 1.14
|
6.53 ± 1.04
|
6.63 ± 1.03
|
7.69 ± 1.30
|
5.93 ± 1.46
|
6.89 ± 1.36
|
6.61 ± 1.24
|
5.54 ± 1.15
|
15%
|
8.29 ± 1.18
|
7.45 ± 1.46
|
7.82 ± 1.42
|
7.73 ± 1.35
|
7.69 ± 1.33
|
8.48 ± 1.80
|
6.53 ± 1.14
|
7.02 ± 1.23
|
7.18 ± 1.27
|
8.18 ± 1.40
|
6.52 ± 1.79
|
7.66 ± 1.52
|
7.34 ± 1.57
|
5.88 ± 1.34
|
25%
|
9.60 ± 1.33
|
9.31 ± 2.23
|
9.28 ± 1.98
|
9.34 ± 1.88
|
8.90 ± 1.80
|
9.82 ± 2.02
|
8.19 ± 1.90
|
8.51 ± 2.06
|
8.79 ± 1.86
|
10.04 ± 2.08
|
7.79 ± 2.03
|
9.04 ± 1.94
|
8.94 ± 1.84
|
7.44 ± 1.83
|
35%
|
10.61 ± 1.45
|
11.82 ± 2.46
|
11.61 ± 2.59
|
11.41 ± 2.37
|
10.07 ± 1.94
|
11.15 ± 1.98
|
10.22 ± 2.53
|
10.75 ± 2.84
|
10.93 ± 2.56
|
11.89 ± 2.39
|
9.42 ± 2.19
|
10.79 ± 2.16
|
10.60 ± 2.14
|
9.15 ± 2.03
|
45%
|
10.80 ± 1.47
|
11.19 ± 2.63
|
11.87 ± 2.49
|
12.03 ± 2.32
|
10.75 ± 2.10
|
10.75 ± 1.98
|
9.48 ± 2.28
|
10.75 ± 2.88
|
10.79 ± 2.70
|
11.40 ± 2.47
|
9.39 ± 2.07
|
10.83 ± 2.31
|
10.51 ± 2.30
|
8.73 ± 2.16
|
55%
|
10.24 ± 1.58
|
9.05 ± 2.09
|
9.56 ± 3.31
|
9.35 ± 2.01
|
9.65 ± 4.13
|
9.29 ± 1.88
|
7.45 ± 1.45
|
7.93 ± 1.79
|
8.00 ± 2.06
|
9.04 ± 2.10
|
7.28 ± 1.78
|
8.71 ± 3.62
|
8.40 ± 2.01
|
6.95 ± 1.89
|
65%
|
9.22 ± 1.34
|
8.23 ± 1.57
|
8.49 ± 1.45
|
8.95 ± 1.51
|
8.71 ± 1.49
|
8.63 ± 1.66
|
6.67 ± 1.18
|
7.06 ± 1.24
|
7.13 ± 1.26
|
8.47 ± 1.52
|
6.61 ± 1.66
|
7.64 ± 1.55
|
7.47 ± 1.50
|
6.35 ± 1.49
|
75%
|
8.85 ± 1.32
|
7.93 ± 1.44
|
8.19 ± 1.19
|
8.86 ± 3.78
|
8.57 ± 1.44
|
8.45 ± 1.68
|
6.47 ± 1.15
|
6.91 ± 1.17
|
7.07 ± 1.31
|
8.47 ± 1.55
|
6.53 ± 1.68
|
7.57 ± 1.66
|
7.35 ± 1.63
|
6.30 ± 1.49
|
85%
|
8.59 ± 1.19
|
7.73 ± 1.45
|
8.26 ± 3.62
|
8.31 ± 1.37
|
8.28 ± 1.33
|
8.27 ± 1.62
|
6.29 ± 1.10
|
6.73 ± 1.08
|
7.16 ± 3.83
|
8.17 ± 1.43
|
6.38 ± 1.67
|
7.35 ± 1.63
|
7.16 ± 1.62
|
6.07 ± 1.48
|
95%
|
8.02 ± 1.22
|
7.03 ± 1.14
|
7.66 ± 1.12
|
7.85 ± 1.26
|
7.61 ± 1.27
|
7.81 ± 1.63
|
5.93 ± 0.95
|
6.38 ± 0.98
|
6.54 ± 0.99
|
7.72 ± 1.28
|
5.89 ± 1.48
|
6.87 ± 1.53
|
6.65 ± 1.41
|
5.60 ± 1.21
|
t
|
-1.892
|
-5.248
|
-2.879
|
-1.571
|
-0.596
|
-7.641
|
-8.179
|
-7.447
|
-6.332
|
-6.541
|
-6.940
|
-6.388
|
-7.132
|
-5.404
|
p-value
|
0.059
|
< 0.001
|
0.004
|
0.117
|
0.551
|
< 0.001
|
< 0.001
|
< 0.001
|
< 0.001
|
< 0.001
|
< 0.001
|
< 0.001
|
< 0.001
|
< 0.001
|
Septum—interventricular septum; Ant—anterior; Ant-Lat— antero-lateral; Post-Lat—infero-lateral; Inf—inferior |
3.4 RA parameters in different cardiac cycles
Table 2 list the mean ± sd of the right atrial major dimension (RA-A) and the mean values of the RA minor dimension (RA-B) in different cardiac phases, while Fig. 2C shows the change trends. For RA-A and RA-B, the maximum and minimum values were observed in the 45% phase and 95% phase, respectively. The maximum values of RA-A and RA-B were 45.58 ± 5.18 mm and 49.68 ± 5.26 mm, respectively. The variations of RA-B in cardiac cycles were of statistical significance, while the variations of RA-A in cardiac cycles were non-significant. Compared with RA-A, RA-B changes more stably during the cardiac cycle.
3.5 RV parameters in different cardiac cycles
Table 2 list mean ± sd of the RV chamber dimensions (RVD1, RVD2, RVD3) in different cardiac phases. The maximum and minimum values of RV dimensions were observed in the 95–5% phase and 35–45% phase, respectively. The maximum values of RV-D1, RV-D2, and RV-D3 were 42.13 ± 5.19 mm, 31.83 ± 5.69 mm and 74.35 ± 7.96 mm, respectively. The variation of RV-D1 and RV-D2 in cardiac cycles was of statistical significance, while the variation of RV-D3 in cardiac cycles was non-significant. Among these diameters, RV-D2 showed the most stable changes during the cardiac cycle.
In addition, the comparison of clinical characteristics and cardiac parameters between male and female subjects revealed significant discrepancy in individual characteristics, including age, BSA, HR, LVMM, smoking, drinking, and diabetes. These differences were also significantly related to gender. Upper and lower reference limits were higher in men than in women. Therefore, we generated cardiac parameters reference ranges on cardiac CT in different cardiac phases for both genders for our population in supplemental material.
3.6 Reproducibility
Inter- and intraobserver ICCs were determined randomly among 126 patients. Interobserver ICCs of 0.913 for LA-A, 0.920 for LA-B, 0.935 for LV-D1, 0.926 for LV-D2, 0.917 for LV-D3, 0.925 for RA-A, 0.921 for RA-B, 0.936 for RV-D1, 0.956 for RV-D2 and 0.941 for RV-D3 were obtained. Also, intraobserver ICCs of 0.902 for LA-A, 0.912 for LA-B, 0.928 for LV-D1, 0.915 for LV-D2, 0.903 for LV-D3, 0.901 for RA-A, 0.907 for RA-B, 0.924 for RV-D1, 0.917 for RV-D2 and 0.916 for RV-D3 were obtained.