Clinical characteristics of the study population
Among the 87 screened patients, eight were excluded because of poor-quality CT images, and three were excluded because of too many segments with poor tracking. Three of our patients had coronary angiography (CAG) results, the percentage of LAD stenosis of them were 60%, 75%, 90%, respectively. The remaining 73 patients were assessed by coronary CT angiography (CTA). Then patients were divided into four groups according to the percentage of LAD stenosis: ≤25% was defined as group I (24 patients), 26–49% as group II (17 patients), 50–74% as group III (21 patients), and ≥ 75% as group IV (14 patients). Simultaneously, thirty-two sex- and age-matched normal subjects were included as controls.
The demographics, clinical data and medical history of the subjects included in the present study are shown in Table 1. The mean age was similar between the patients and controls. Patients with LAD stenosis were predominantly male. This cohort had a high prevalence of hypertension, but there were no statistically significant differences between the groups with respect to hypertension, diabetes, smoking or alcohol consumption.
Table 1
Clinical characteristics of the study population
Variable | Group I (n = 24) | Group II (n = 17) | Group III (n = 21) | Group IV (n = 14) | Control (n = 32) | P values |
Age (years) | 56.7 ± 8 | 54.1 ± 12 | 62 ± 10 | 61 ± 13 | 56.7 ± 11 | 0.255 |
Male (n, %) | 17(70.8) | 14(82.4) | 17(81) | 11(78.6) | 19(57.6) | 0.249 |
BMI (kg/m2) | 24.9 ± 3 | 25.1 ± 5 | 23.9 ± 4 | 24.8 ± 3 | 24.8 ± 3 | 0.399 |
Smoking history (Yes/No) | 9/15 | 5/12 | 7/14 | 7/7 | 10/22 | 0.730 |
Drink history (Yes/No) | 8/16 | 4/13 | 8/13 | 5/9 | 7/25 | 0.707 |
Heart rate(beats/min) | 70.1 | 71.1 | 69.4 | 71.0 | 69.7 | 0.986 |
Hypertension (n, %) | 11(45.8) | 9(52.9) | 8(38.1) | 7(50%) | 0 | 0.204 |
SBP | 136 ± 20 | 131 ± 18 | 141 ± 20 | 144 ± 23 | 126 ± 16 | 0.013 |
DBP | 88 ± 16 | 85 ± 15 | 88 ± 15 | 89 ± 12 | 79 ± 16 | 0.091 |
Diabetes mellitus (n, %) | 4(16.7) | 1(5.9) | 5(23.8) | 2(14.3) | 0 | 0.386 |
Medication | | | | | | |
ACEIs (Yes/No) | 9/15 | 7/10 | 9/12 | 9/5 | -- | -- |
Diuretics (Yes/No) | 5/19 | 4/13 | 8/13 | 7/7 | -- | -- |
CCBs (Yes/No) | 8/16 | 6/11 | 10/11 | 10/4 | -- | -- |
β-Blockers (Yes/No) | 6/18 | 4/13 | 5/16 | 9/5 | -- | -- |
Statins (Yes/No) | 2/22 | 3/14 | 3/19 | 6/8 | -- | -- |
Hematocrit (%) | 139.5 | 140.7 | 133 | 138.3 | 132.2 | -- |
Total cholesterol(mmol/L) | 3.61 | 3.94 | 4.91 | 4.99 | 3.92 | -- |
Triglycerides (mmol/L) | 1.72 | 1.76 | 1.55 | 1.64 | 1.56 | -- |
HDL-C(mmol/L) | 1.1 | 1.58 | 2.61 | 0.952 | 1.31 | -- |
LDL-C (mmol/L) | 2.4 | 2.62 | 2.96 | 2.95 | 3.19 | -- |
All data are expressed as the mean ± SD, percentage (number of participants), or median (interquartile range), as appropriate. |
*P < 0.05 between groups. |
BMI, body mass index; SBP, systolic blood pressure; DBP, diastolic blood pressure; LVH, left ventricular hypertrophy; ACEIs, angiotensin-converting enzyme inhibitors; ARBs, angiotensin II receptor blockers; CCBs, channel blockers, HDL-C, High density liptein cholesterol; LDL-C, low density liptein cholesterol. |
Volume And Function Of The Left Ventricle
No significant intergroup differences were found between groups I-IV and the controls in terms of the left ventricular ejection fraction (LVEF) (p = 0.586), end-diastolic volume (EDV) (p = 0.719) and end-systolic volume (ESV) (p = 0.257) (Table 1).
Parameters Of CT-FT-derived Strain Among The Study Groups
The longitudinal strain (LS) of the LAD territory was significantly reduced in groups I-IV compared with the controls (-20.8% and − 18.5% and − 18.6% and − 17.0% vs 23.7%, respectively). The peak value of LS decreased as the stenosis degree of the LAD increased; specifically, the higher the degree of stenosis was, the lower the LS value. In addition, the circumferential strain (CS) of LAD territory was significantly reduced in groups III and IV compared with the controls and groups I and II (-22.4% and − 22.2% vs -25.4% and − 24.1% and − 25.3%, respectively), but the amplitudes of radial strain (RS) showed no significant differences among the five groups (Table 2).
Table 2
Cardiac CT parameter of the study population
Variable | Group I (n = 24) | Group II (n = 17) | Group III (n = 21) | Group IV (n = 14) | Control (n = 32) | P values |
LVEF (%) | 63.3 ± 9 | 63.6 ± 8 | 63.1 ± 9 | 59 ± 13 | 63.9 ± 7 | 0.586 |
LVEDV (ml) | 90 ± 19 | 84.9 ± 30 | 82.5 ± 19 | 90.1 ± 17 | 87 ± 15 | 0.719 |
LVESV (ml) | 32.8 ± 10 | 40.6 ± 18 | 30.9 ± 11 | 37.3 ± 17 | 32 ± 10 | 0.257 |
CS (%) | | | | | | |
LAD territory (%) | -24.1 ± 4 | -25.3 ± 6 | -22.4 ± 4*,a | -22.1 ± 4*,a,b | -25.4 ± 4 | 0.062 |
Non- LAD territory (%) | -25.6 ± 5 | -24.4 ± 4 | -25.9 ± 4 | -22.9 ± 5 | -27.4 ± 5 | 0.052 |
GCS (%) | -25 ± 4 | -24.1 ± 4 | -24.7 ± 6 | -22.4 ± 4 | -26.6 ± 4 | 0.115 |
RS (%) | | | | | | |
LAD territory (%) | 76.6 ± 25 | 79.1 ± 42 | 93.1 ± 56 | 63 ± 23 | 88 ± 38 | 0.186 |
Non- LAD territory (%) | 90 ± 36 | 96.5 ± 80 | 74.9 ± 23 | 76.4 ± 26 | 84.3 ± 28 | 0.74 |
GRS (%) | 85.1 ± 26 | 89.1 ± 55 | 81.4 ± 25 | 71.7 ± 23 | 85.3 ± 32 | 0.628 |
LS (%) | | | | | | |
LAD territory (%) | -20.8 ± 3 | -18.6 ± 4*,a | -18.6 ± 3*,a,b | -17 ± 5*,a,b,c | -23.7 ± 3 | ༜0.001 |
Non- LAD territory (%) | -22.0 ± 3 | -21.9 ± 3 | -21.9 ± 2 | -20 ± 4 | -22.0 ± 4 | 0.488 |
GLS (%) | -20.1 ± 2 | -20.3 ± 3* | -20.5 ± 3*,a | -18.7 ± 4*,a,b,c | -22.9 ± 3 | ༜0.001 |
All data are expressed as the mean ± SD, percentage (number of participants), or median (interquartile range), as appropriate. |
*P < 0.05 compared with normal controls. |
a P < 0.05 compared with groups I. |
b P < 0.05 compared with groups II. |
c P < 0.05 compared with groups III. |
HR, heart rate; LVEF, left ventricular ejection fraction; LVEDV, left ventricular end-diastolic volume; LVESV, left ventricular end-systolic volume; RS, radial strain; CS, circumferential strain; LS, longitudinal strain; GRS, global radial strain; GCS, global circumferential strain; GLS, global longitudinal strain. |
Comparison of strain between LAD territory and non-LAD territory in groups I-IV
Compared with LAD non-territory, groups II-IV had significantly increased LS values in the LAD territory (-19.9% vs -21%, p = 0.07; -18.6% vs -21.9%, p = 0.024; -16.4% vs -20.1%, p = 0.032, respectively), which was not observed in the controls or group I. Group III had a significantly increased CS of the LAD territory compared with that of the non-LAD territory (-23% vs -25.9%, p = 0.03), which was not observed in other groups. However, no significant differences were found between the RS of LAD territory and that of non-LAD territory in the five groups (Table 3).
Table 3
Peak systolic strain of patients of between the LAD territory and non-LAD territory
Variable | Strain of LAD territory | Strain of non-LAD territory | P values |
Group I | | | |
CS | -24.1 ± 4 | -25.6 ± 5 | 0.269 |
RS | 76.6 ± 25 | 90 ± 36 | 0.133 |
LS | -20.8 ± 3 | -22.0 ± 3 | 0..085 |
Group II | | | |
CS | -25.3 ± 6 | -24.4 ± 4 | 0.625 |
RS | 79.1 ± 42 | 96.5 ± 80 | 0.432 |
LS | -18.6 ± 4 | -21.9 ± 3 | 0.007 |
Group III | | | |
CS | -22.4 ± 4 | -25.9 ± 4 | 0.024 |
RS | 93.1 ± 56 | 74.9 ± 23 | 0.175 |
LS | -18.6 ± 3 | -20.5 ± 3 | 0.030 |
Group IV | | | |
CS | -22.1 ± 4 | -22.9 ± 5 | 0.856 |
RS | 63 ± 23 | 76.4 ± 26 | 0.184 |
LS | -17 ± 5 | -18.7 ± 4 | 0.032 |
Control | | | |
CS | -25.4 ± 4 | -27.4 ± 5 | 0.203 |
RS | 88 ± 38 | 84.3 ± 28 | 0.750 |
LS | -23.7 ± 3 | -22.9 ± 3 | 0.431 |
All data are expressed as the mean ± SD, percentage (number of participants), or median (interquartile range), as appropriate. |
*P < 0.05 between groups. |
LAD, left anterior descending; RS, radial strain; CS, circumferential strain; LS, longitudinal strain. |
Factors associated with myocardial strain of LAD territory in the patient group
These results are shown in Table 4. In the patient group, the LS of the LAD territory was significantly correlated with the severity of LAD stenosis (r = 0.438, p = 0.002) (Fig. 4), angiotensin-converting enzyme inhibitor (ACEI) treatment (r=-0.235, p = 0.041), level of High density liptein cholesterol(HDL-C)((r=-0.551,p = 0.008) ,and LVEF (r=-0.315, p = 0.009). In addition, the CS of the LAD territory showed a significant negative correlation with the LVESV (r=-0.324, p = 0.002) and LVEF (r=-0.323, p = 0.005). The RS showed a negative significant correlation with the LVEDV (r = 0.304, p༜0.008). However, no significant associations were observed between cardiac strain (CS, RS and LS) in the LAD territory and age, heart rate, hypertension, history of smoking, history of alcohol consumption, BMI, DM, or other medications.
Table 4. Univariate correlation coefficients for RS, CS and LS of
LAD territory in patients with LAD stenosis
| CS (%) | | RS (%) | | LS (%) | |
Variable | R value | P value | | R value | P value | | R value | P value |
Age (years) | -0.062 | 0.597 | | -0.013 | 0.912 | | -0.07 | 0.548 | |
Sex | 0.104 | 0.371 | | -0.023 | 0.845 | | 0.242 | 0.073 |
BMI (kg/m2) | 0.088 | 0.448 | | 0.027 | 0.816 | | 0.061 | 0.604 |
Hypertension | 0.036 | 0.756 | | -0.126 | 0.276 | | -0.038 | 0.747 |
SBP (mmHg) | 0.057 | 0.623 | | 0.102 | 0.382 | | 0.108 | 0.352 |
DBP (mmHg) | 0.041 | 0.728 | | -0.081 | 0.488 | | 0.042 | 0.721 |
DM | 0.109 | 0.349 | | -0.136 | -0.241 | | -0.020 | 0.864 |
History of smoking | -0.027 | 0.817 | | -0.14 | -0.227 | | -0.053 | -0.647 |
History of drinking | -0.035 | 0.764 | | -0.06 | 0.606 | | -0.108 | 0.351 |
HR | 0.052 | 0.657 | | 0.053 | 0.649 | | 0.048 | 0.680 |
ACEIs (Yes/No) | -0.181 | 0.119 | | 0.070 | 0.550 | | -0.235 | 0.041* |
Diuretics (Yes/No) | -0.014 | 0.905 | | 0.013 | 0.913 | | -0.184 | 0.112 |
CCBs (Yes/No) | -0.166 | 0.151 | | -0.041 | 0.241 | | -0.136 | 0.241 |
β-Blockers (Yes/No) | -0.020 | 0.864 | | -0.013 | 0.913 | | -0.110 | 0.345 |
Statins (Yes/No) | 0.076 | 0.513 | | -0.011 | 0.922 | | -0.091 | 0.435 |
Hematocrit (%) | 0.307 | 0.093 | | -0.067 | 0.736 | | -0.024 | 0.903 |
Total cholesterol(mmol/L) | 0.211 | 0.322 | | 0.262 | 0.216 | | -0.024 | 0.903 |
Triglycerides (mmol/L) | 0.009 | 0.969 | | 0.180 | 0.423 | | 0.069 | 0.749 |
HDL-C(mmol/L) | 0.115 | 0.610 | | 0.219 | 0.328 | | -0.551 | 0.008* |
LDL-C (mmol/L) | 0.365 | 0.086 | | -0.125 | 0.579 | | -0.203 | 0.365 |
Degree of stenosis | 0.196 | 0.090* | | -0.029 | -0.803 | | 0.438 | 0.002 |
LVEF (%) | -0.323 | 0.005* | | 0.115 | 0.324 | | -0.315 | 0.009 |
LVEDV (ml) | 0.092 | 0.427 | | -0.304 | 0.008* | | 0.083 | 0.474 |
LVESV(ml) | -0.324 | 0.002* | | -0.1 | 0.388 | | -0.229 | -0.460 | |
Correlation analysis are using Person correlation. |
*P < 0.05 between groups. |
BMI, body mass index; SBP, systolic blood pressure; DBP, diastolic blood pressure; LVH, left ventricular hypertrophy; ACEIs, angiotensin-converting enzyme inhibitors; CCBs, channel blockers. HR, heart rate; LVEF, left ventricular ejection fraction; HDL-C, High density liptein cholesterol; LDL-C, low density liptein cholesterol, LVEDV, left ventricular end-diastolic volume; LVESV, left ventricular end-systolic volume; RS, radial strain; CS, circumferential strain; LS, longitudinal strain, |
Intra- And Interobserver Reproducibility
The intra-class correlation coefficient (ICC) value in the intraobserver analysis was 0.973 for the percentage of LAD stenosis on CTA. The ICC of variability was good for the global strain values and the average segmental amplitude of strain in the LAD territory (Table 5).
Table 5
Intra- and interobserver reproducibility of CT-FT strain
Strain | Coefficient of variability (%) | ICC(95%CI) |
Interobserver variability | | |
LAD CS | 7.0 | 0.90(0.86–0.93) |
LAD RS | 6.7 | 0.88(0.79–0.96) |
LAD LS | 6.5 | 0.86(0.84–0.89) |
GCS | 7.8 | 0.96(0.93-1.00) |
GRS | 7.4 | 0.94(0.92-1.00) |
GLS | 6.6 | 0.87(0.85–0.93) |
Intraobserver variability | | |
LAD CS | 5.9 | 0.89(0.84–0.94) |
LAD RS | 6.6 | 0.91(0.86–0.96) |
LAD LS | 7.6 | 0.95(0.90–0.98) |
GCS | 6.1 | 0.91(0.88–0.93) |
GRS | 5.5 | 0.86(0.83–0.91) |
GLS | 7.2 | 0.93(0.90–0.95) |
RS, radial strain; CS, circumferential strain; LS, longitudinal strain; GRS, global radial strain; GCS, global circumferential strain; GLS, global longitudinal strain. |