| Background and Objective:Epicardial adipose tissue(EAT)is adipose tissue deposited between pericardial visceral membrane and myocardium.It located around heart and coronary arteries.EAT can be measured by CT plain scaning with less radiation dose.Therefore,EAT represents a great potential noninvasive imaging marker in prediction and diagnosis of cardiovascular disease.The correlation between EAT and coronary atherosclerotic lesions has became research focuses recently.Previous studies have shown that abnormal accumulation of EAT is associated with coronary artery stenosis,calcification grade and plaque progression by local and systemic inflammatory change.According to this,It has clinical meaning to find correlation between EAT and coronary atherosclerotic lesion.Furthermore,it is important to explore a new risk stratification marker,new intervention target and prediction model to predict cardiovascular outcome.However,the relationship between EAT and GHD has not been clarified.The association between EAT and plaques composition,high-risk vulnerable characteristics and functional changes were still unclear.The purpose of this study was to explore the relationship between EAT volume and severity of coronary lesion,plaque precise composition,functional hemodynamic abnormal using coronary computed tomography angiography,and to detect clinical relevance between EAT volume and coronary atherosclerosis lesion.Methods:First part:217 patients with suspected CHD who underwent coronary CTA examination from September to December 2015 were enrolled retrospectively.The patients were divided into obstructive CHD group(46 cases)and non obstructive CHD group(171 cases)according to whether coronary diameter stenosis?50%.The correlation between EAT volume and CAD-RADS(Coronary heart disease reporting and data system)degree,coronary artery stenosis,total plaque burden and coronary artery calcification score(CACS)were analyzed.The patients were followed up for 2 years and the major adverse cardiovascular events(MACEs)were recorded,then the relationship between EAT volume and MACEs was preliminarily analyzed.Second part:101 patients with suspected CHD underwent coronary CTA examination from March to July 2017,whose clinical data and symptoms met diagnostic criteria of acute coronary syndrome(ACS)and stable angina pectoris(SAP)were enrolled.70 cases were diagnosed as ACS and 31 cases were SAP.Based on coronary CTA imaging atherosclerotic plaque precise quantitive analysis,we measured the volume and burden of various plaque compositions.EAT volume and plaque composition between ACS and SAP group were compared,.as well as the correlation between EAT volume and plaque composition was analyzed.According to presence of high risk plaque,multivariable logistic regression analysis was used to explore the OR of risk factors about high risk plaque.Third part:138 patients with suspected CHD who underwent coronary CTA examination from January 2012 to December 2016,then underwent coronary angiography and fraction flow reserve(FFR)examination within 1 month after CTA examination were enrolled.According to FFR results,patients were divided into myocardial ischemia group(60 cases)and non myocardial ischemia group(78 cases).The total EAT and vEAT volume were measured.The difference of total EAT as well as vEAT volume between two groups was compared.Multivariable logistic regression analysis was performed to explore OR of risk factor about ischemia.The risk prediction model of myocardial ischemia was established by complex indices,then predicting performance and risk restratification ability of the model was evaluated.Results:First part:EAT volume of obstructive CHD group was higher than that of non obstructive CHD group(174.1±49.9cm3 vs.149.6±49.0cm3,P=0.003).With increasing of CAD-RADS degree,EAT volume is also increased,and there was a significant positive correlation between EAT volume and CAD-RADS degree(r=0.216,P=0.014).There were also positive correlation between EAT volume and coronary artery stenosis(r=0.181,P=0.039),total plaque burden(r=0.206,P=0.019).The EAT volume of MACEs was significantly higher than that of without MACEs group(192.1 ±45.2cm3 vs.152.5 ±49.6cm3,P=0.005).The Kaplan-Meier survival curve analysis showed that EAT volume?157.6cm3 group demonstrated more adverse cardiovascular outcome within about 2 years.Second part:EAT volume in ACS group was significantly higher than that of SAP group(143.7±49.8cm3 vs.123.3±39.2cm3,P=0.046).EAT volume demonstrated a significant positive correlation with total plaque burden(r=0.298,P=0.003),non calcified plaque burden(r=0.245,P=0.013)and lipid plaque burden(r=0.250,P=0.012).Intra-group correlation analysis showed that EAT volume was positively correlated with total plaque burden(r=0.309,P=0.009),non calcified plaque burden(r=0.242,P=0.044)and lipid plaque burden(r=0.240,P=0.045)in ACS group,however,no correlation was observed in SAP group.EAT volume with high risk plaque was significantly higher than those without high risk plaque(169±6.2cm3 vs.130.6±5.3cm3,P=0.002).After adjustment by traditional risk factors and CACS,multivariable logistic regression analysis showed EAT volume was an independent risk predictor of presence of high risk plaque[OR:1.018(95%CI:1.006-1.031),P=0.004].Third part:LAD-vEAT volume of myocardial ischemia group was higher than that of non ischemic group(28.7±1.4cm3 vs.23.9±1.0cm3,P=0.005).LAD-vEAT volume is positively correlated with LCX-vEAT volume(r=0.72,P<0.001),RCA-vEAT volume(r=0.74,P<0.001)and total EAT volume(r=0.77,P<0.001).The ROC curve determined that the cut off value of diagnosis of LAD-vEAT volume for myocardial ischemia was 24.6cm3.Multivariable logistic regression analysis after adjustment by traditional risk factors,CACS and CAD-RADS degree,LAD-vEAT volume ?24.6cm3 was an independent risk predictor of myocardial ischemia[OR:3.351(95%CI:1.540-7.290),P=0.002].Combined with LAD-vEAT volume?24.6cm3,predictive performance(AUC:0.795 vs.0.733,P<0.05)and risk restratification ability(NRI:0.186,P=0.037)was improved compare with the previous model.Conclusions:1.Using coronary CTA as a method to evaluate CHD severity,we found EAT volume increased was higher in more severity lesions.There was association between EAT volume and cardiovascular events for 2 years,and adverse cardiovascular outcomes were more likely to occur in higher EAT volume patients.2.There was a significant correlation between EAT volume and plaque characteristics.With the increasing EAT volume,total plaque burden,non calcified plaque burden and lipid plaque burden increased significantly.In ACS group,there was a positive correlation between EAT volume and total plaque burden,non calcified plaque burden and lipid plaque burden,but the correlation was not observed in SAP group.EAT volume was an independent risk predictor of high risk plaque,which means EAT may play an important role in the presence and progression of high risk plaque.3.The FFR measurements were used as gold standard to evaluate myocardial ischemia,and LAD-vEAT volume in ischemia group was significantly higher than that of non ischemia group.LAD-vEAT volume of was highly correlated to other parts EAT volume,and may be a good representative of local visceral adipose tissue.LAD-vEAT volume ?4.6cm3 was an independent risk predictor of myocardial ischemia.The predicting performance and risk restratification ability of combined model with LAD-vEAT volume ?24.6cm3 were improved. |
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