| Part one:Assessment of coronary elasticity with 256iCT:a feasibility study and analyse the related risk factors of coronary elasticity of subclinical coronary arteriosclerosisObjective:To evaluate the feasibility of CCTA by 256 slice intelligent CT(256iCT)in the assessment of coronary elasticity and analyse the related risk factors of coronary elasticity of subclinical coronary arteriosclerosisMaterials and Methods:64 subjects(29 males,35 femals, aged 38-77 years with a mean of 53.4±9.2 yesrs) of no significant organical coronary disease were enrolled in our study. The lifestyle and clinical characteristics of all participants were obtained by completion of a questionnaire and checked by interview.We collected information including height, weight, smoking status, alcohol consumption and whether with abnormal lipid levels, history of hypertension, diabetes and a family history of cardiovascular disease or not. Blood pressure were measured once before examination and again after it.All participants were subjected to CCTA using 256iCT (philips, Netherlands). Raw data were reconstructed in 5% steps between 5 and 95% of the RR interval from the ECG. We obtained 19 phases images in each participant. The maximum and minimum cross-sectional areas of the region of interest(ROI) were measured in the left main-anterior descending coronary artery(LM-LAD). The measurement site was located 2 to 3 cm from the coronary artery export and avoided branch openings, then calculated the maximum diameter and minimum diameter by a formula.We adopted two common parameters to assess the coronary elasticity:coronary distensibility index(CDI, 10-3mmHg-1) and coronary stiffness(β). Two-sample Mest was applied to analyse the difference between positive events (hypertension, high cholesterol, diabetes, male, elderly, overweight, smoking history, drinking history and family history of cardiovascular disease) and negative events of CDI and β. The multiple linear regression was uesd for analyse the independent risk factors of coronary elasticity of subclinical coronary arteriosclerosis.Results1. Correlation of left ventricular volume with the left main coronary-left anterior descending artery(LM-LAD) diameterThe blood flow of coronary artery was closely related with the systolic of heart and left ventricular ejection fraction (LVEF). The results showes that There were 82.8%(53/64) subjects best diastolic phase of ROI loated in 45% and 50% phase of cardiac cycle, them considered as early diastolic of left ventricular phase. There were 73.4%(47/64) subjects best systolic phase of ROI located in 65% ,70% and 75% phase of caediac cycle, them considered as middle diastolic of left ventricular phase.2.Accuray of measurement of the area of ROIThere repeated measurement of the area of ROI shows that there were no significant differences between the maximum (12.38±3.51mm2 vs 12.33±3.48 mm2 vs12.17±3.66mm2, F=0.052,P=0.950)and minimum (9.85±2.73mm2 vs 9.89±2.76 mm2 vs 9.70±2.87 mm2, F=0.064, P=0.938) area of ROI. Statistical results indicated there were no significant differences between intraobserver and interobserver using repeated measurements, the average data of the three measurements were Smax=12.31±3.46 mm2 and Smin=9.86±2.91 mm2.By the formula S= π × (D/2) 2 to obtain an average maximum diameter Dmax(4.05 ± 0.60 mm) and the minimum diameter Dmin (3.63 ±1.11 mm).And calculate all the subjects LM-LAD branch of the same ROI for the CDI 1.96-9.32 x 10-3mmHg-1, with an average of 5.32 ± 2.11 × 10"3mmHg-’and β of 2.75-3.32, with an average of 2.42 ±0.31.3. According to all subjects on the basis of clinical data divided into positive and negative event group, positive events including hypertension, high cholesterol, diabetes, male, elderly (age> 60 years), overweight (BMI> 24Kg/m2), with a family history of cardiovascular disease, smoking history, drinking history,then using two independent samples t test for statistical comparison of coronary artery elastic parameters (CDI and β) in positive events and negative events group.The results showed that the CDI of the group of hypertension (3.69±1.12 x 10-3mmHg-1vs 6.12 ± 2.04×10-3mmHg-3mmHg-1,t=6.125, P＜0.001), diabetic (3.74±1.24×10-3mmHg-1 vs 5.89±2.12×10-3mmHg-1, t=3.671, P=0.002) and elder (3.66±1.4×10-3mmHg-1 vs 5.75±2.06×10-3mmHg-1, t=3.451, P=0.001) were lower than the group of non-hypertensive, the non-diabetic and the young. The P of the group of Hypertension (2.65 ± 0.30 vs 2.32 ± 0.26, t= 4.56, P＜0.001), diabetic (2.72 ± 0.33 vs 2.34 ± 0.29, t= 3.227, P= 0.002), elder (2.60 ± 0.25 vs 2.38 ± 0.22, t= 2.283,P= 0.026) were lower than the group of negative events. However, there were no significant difference in CDI and P between the group of hyperlipidemia, male, having a family history of cardiovascular disease, smoking, alcohol and the group of negative events.4. Analyse the related risk factors of coronary elasticity of subclinical coronary arteriosclerosis by multivariate linear regression analysisThe independent risk factor for coronary artery elastic parameters chose from these traditional cardiovascular factors through multiple linear regression analysis. We considered the coronary artery elastic parameters (CDI and P) as the dependent variable, factors related to coronary artery elastic parameters as independent variables (including hypertension, high cholesterol, diabetes, age, gender, family history of cardiovascular disease, smoking history, drinking history and BMI). All data were analyzed with multiple regression (stepwise).CDI was independently associated with age, hypertension, pulse pressure and BMI (R2=0.521, P<0.001);β was independently associated with age, hypertension, diabetes and pulse pressure(R2=0.420, P＜0.001).Conclusions:1. Retrospective ECG-gated CCTA by 256iCT can obtain the data of regular diastole and systole of the coronary artery, so it is a feasible and novel modality to assess coronary artery elasticity.2. There are different variation and sensibility among elastic parameters. Considering the difference, we should omnibusly apply the elastic parameters.3. Changes in coronary elasticity would occurs earlier than structure for patients who is subclinical coronary atherosclerosis. Hypertension, diabetes, age and BMI were independent risk factors for coronary elasticity in subclnical coronary atherosclerosis. Effects of high cholesterol, sex, BMI, smoking, alcohol consumption and family history of cardiovascular disease to coronary elasticity in subclnical coronary atherosclerosis have not been confirmed, further study should be did.Part 2:Correlation of Coronary elasticity with the severity of coronary artery disease by 256iCTObjective:To evaluate the correlation of coronary elasticity with the severity of coronary artery disease by 256-row computed tomography angiographyMaterials and Methods:We enrolled 87 subjects(46 males, aged 38-77 years, mean age:53.4±9.2 years) who were suspected coronary artery disease(CAD). Of whom 47 subjects suffered from CAD. According to the condition of coronary, all subject were divided into normal coronary, mild CAD, moderate CAD and severe CAD. Controled group were choosed from the subjects in part one,40 subjects were enrolled in this part and matched with age and sex. The basic characteristics of all subjects were obtained as part one, including height, weight, smoking status, alcohol consumption and whether with abnormal lipid levels, hypertension, history of diabetes and a family history of cardiovascular disease or not. The maximum and minimum volumes and cross-sectional areas of the region of interest (ROI) were measured as part one. The selection of ROI not only avoid of furcation but also the plaque or stenosis. Spearman correlation was applied for analyzed the correlation between coronary artery elasticity and the severity of CAD.meanwhile, using multiple linear regression analyst the independent risk factors of coronary artery elasticity.Results1.Comparison of basic characteristics of different groups of CADAll subjects were divided into 4 groups,40 subjects with normal coronary,22 subjects with mild CAD,14 subjects with moderate CAD,11 subjects with severe CAD. The results shows that the difference ofsex, age,BMI, LVEF, and the morbidity of hypertension, high cholesterol, diabetes, family history of cardiovascular disease, smoking history, drinking history among different groups have no statistically significant (all P>0.05).However,the difference of the morbidity of hypertension 25% vs 31.8% vs 28.6% vs 72.7%,P=0.028)and high cholesteroL( 15% vs 22.7% vs 28.6% vs 63.6%, P=0.033) have statistically significant.2.Comparison of coronary elasticity of different groups of CADCompared with the difference of coronary elasticity of 4 groups, the difference of CDI (5.38±1.98×10-3mmHg-1 vs 4.34±1.40×10-3mmHg-1 vs 3.37±1.57×10-3mmHg-1 vs 3.0±1.23×10-3mmHg-1, P＜0.001) and β (2.36±0.26 vs 2.46±0.25 vs 2.73±0.35 vs 2.72±0.30, P＜0.001) ware statistically significant.Spearman correlation shows different group of CAD was negatively correlated with the CDI (r=-0.491, P＜0.001) and positively correlated with P (r=0.372, P＜0.001)The independent risk factor for coronary artery elastic parameters chose from the many traditional cardiovascular factors through multiple linear regression analysis,in coronary artery elastic parameters (CDI and β) as the dependent variable, factors related to coronary artery elastic parameters as independent variables (including hypertension, high cholesterol, diabetes, age, gender, family history of cardiovascular disease, smoking history, drinking history and BMI), all data were analyzed using multiple regression (stepwise).CDI was independently associated with age, the severity of coronary artery disease, hypertension and high cholesterol (R2=0.612, P<0.001); β was independently associated with age, the severity of CAD and hypertension (R2=0.530, P<0.001)Conclusion1. The decrease of coronary is throughout the process of atherosclerosis of coronary artery. Along with the exacerbation of coronary artery disease, the coronary elasticity will diminished.2. With the progression of atherosclerosis of coronary coronary, the independent risk factors of coronary elasticity were more than early atherosclerosis. Hypertension, pulse pressure, systolic blood pressure, high cholesterol, diabetes, age and coronary artery disease would make different effects on coronary elasticity. |
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