Non-invasive Quantitative Plaque Analysis By Coronary Computed Tomography Angiography And CT-FFR In Predicting Coronary Lesion-specific Myocardial Ischemia

Objective:To evaluate the diagnostic performance of the automated quantitative analysis and FFR by coronary computed tomography angiography for coronary lesion-specific myocardial ischemia assessed by fractional flow reserve.Methods:First part:142 patients with 169 vessels(with 30-90%diameter stenosis),who successively underwent invasive coronary angiography with evaluation of FFR(values?0.8 were defined as coronary lesion-specific myocardial ischemia),were analyzed by coronary CT angiography.Coronary CT angiography images were quantitatively analyzed with automated software to obtain the following index:maximum diameter stenosis(MDS%);maximum area stenosis(MAS%);lesion length(LL);volume and burden(plaque volume×100 per vessel volume)of total,calcified,non-calcified,lipid and fibrous plaque;napkin-ring sign;remodeling index and eccentric index.Logistic regression and area under the receiver operating characteristics were used for statistical analysis.Second part:The CT-FFR values of 169 blood vessels studied in the first part were measured by domestic CT-FFR software.A total of 55 blood vessels were measured.Clinical baseline data were collected.The correlation between CT-FFR,lumen stenosis(maximum diameter stenosis rate,maximum area stenosis rate),total plaque volume and it's volume burden with FFR was analyzed by Spearman correlation analysis.And the correlation between lumen stenosis(maximum diameter stenosis rate,maximum area stenosis rate),total plaque volume and it's volume burden with CT-FFR was analyzed by Spearman correlation analysis.Bland-Altman chart was used to analyze the consistency of CT-FFR and FFR values for measuring coronary fractional flow reserve.Based on the blood vessel level,the target vessels were divided into ischemic group(34 cases)and non-ischemic group(21 cases)according to FFR<0.8 and FFR>0.8.To determine the diagnostic efficacy of CT-FFR for ischemia we drew the ROC curve of CT-FFR.Results:First part:FFR<0.80 was found in 57(33.73%)of the 169 vessels.MDS%,MAS%,volume of total plaque,calcified plaque and lipid plaque;burden of total plaque and lipid plaque were significantly larger in ischemic group.Lesion length,napkin-ring sign,remodeling index and eccentric index were not significantly deferent in two groups.In Logistic regression analysis,only MAS%>68%(OR:7.20,95%CI:2.89-17.91,P<0.001),burden of lipid plaque>10.03%(OR:4.32,95%CI:1.36-13.66,P=0.01)were significant predictors of coronary lesion-specific myocardial ischemia.For predicting coronary lesion-specific myocardial ischemia,compared with MDS%,total plaque burden,lipid plaque burden and calcified plaque burden,the AUC of MAS%was significantly increased(0.77 vs.0.71,P<0.05;0.79 vs.0.63,P<0.05;0.79 vs.0.66,P<0.05;0.77vs.0.59,P<0.01).And among addition of other indexes to MAS%(MAS%+MLA%,MAS%+MDS%,MAS%+TPB,MAS%+CPB,MAS%+LPB),only MAS%+LPB was significantly larger than MAS%(0.83 vs.0.77,P<0.05).Second part:A total of 55 vessels were measured,of which 34(61.82%)had coronary lesion-specific ischemia.The results of correlation analysis showed that CT-FFR was highly correlated with FFR(R=0.870,P<0.001).The maximum diameter stenosis rate and the maximum area stenosis rate were moderately correlated with FFR(R=-0.569,P<0.001;R=-0.573,P<0.001).And the maximum diameter stenosis rate and the maximum area stenosis rate were moderately correlated with FFR(R=-0.546,P<0.001;R=-0.528,P<0.001).Bland-Altman diagram shows that CT-FFR and FFR have good consistency.In terms of diagnostic efficacy,ROC curve showed that the AUC of CT-FFR for coronary lesion specific ischemia was 0.97.Conclusions:First part:Compared with diameter stenosis,area stenosis substantially improves the prediction of coronary lesion-specific myocardial ischemia.And compared with area stenosis,addition of burden of lipid plaque to MAS%also substantially improves the prediction of coronary lesion-specific myocardial ischemia.Second part:CT-FFR is highly correlated with FFR,and the maximum diameter stenosis rate and the maximum area stenosis rate are moderately correlated with FFR and CT-FFR.In terms of diagnostic efficacy,CT-FFR can better diagnose coronary lesion-specific ischemia.