Clinical Application Of Coronary CT Angiography Derived Instantaneous Wave-Free Ratio

Background and Objective To diagnose coronary ischemic lesions based on coronary CT angiography(CCTA)-derived instantaneous wave-free ratio(iFRCT)with invasive fractional flow reserve(FRR)as a diagnostic criterion.Materials and methods In this study,206 patients with coronary artery ischemic lesions in 9 centers of China were retrospectively analyzed,and 214 blood vessels treated with CCTA and invasive coronary angiography(ICA)and invasive FFR were reviewed retrospectively.The sensitivity,specificity and accuracy of CCTA,ICA and iFRCT to specific ischemia of vascular lesions in all lesions and critical lesions(lumen stenosis 30%-70%)and the area under the curve(AUC)were calculated by using FFR as the reference criterion.Bland-Altman analysis were used to analyze the agreement between iFRCT and invasive FFR.Results The sensitivity of CCTA,ICA and iFRCT in the measurement of coronary artery ischemic lesions was 0.90,0.96 and 0.86 respectively,the specificity was 0.27,0.28 and 0.67 respectively,the accuracy was 0.54,0.58 and 0.75,the AUC were 0.584,0.625 and 0.767,respectively.For intermediate lesions,the sensitivity,specificity,accuracy and AUC of CCTA were 0.84,0.27,0.46,0.551;those of ICA were 0.95,0.28,0.50,0.614,corresponding to iFRCT the sensitivity,specificity,accuracy and AUC were 0.82,0.68,0.73,0.752.On a per-vessel basis,the specificity and accuracy of coronary artery functional ischemia were higher than that of CCTA and ICA(P<0.001),the negative predictive value of iFRCT was not statistically different(P=0.233),and the sensitivity of ICA was higher than that of iFRCT(P=0.009),there was no significant statistical difference between CCTA and ICA sensitivity(P=0.659),specificity(P=0.557),accuracy(P=0.321).In intermediate lesions,the specificity,accuracy and positive predicted value of the coronary artery functional ischemia estimated by iFRCT were higher than those by CCTA and ICA(all P<0.05).The sensitivity(P=0.067),specificity(P=0.881),accuracy(P=0.445)between CCTA and ICA had no significantly statistical difference.On a per-vessel basis,iFRCT was higher than CCTA(AUC:0.767[95%CI:0.70-0.82]vs.0.584[95%CI:0.52-0.65],p<0.001)in determining the efficacy of coronary artery ischemia diagnosis.p<0.001);On a per-vessel basis,iFRCT is superior to CCTA in detecting CAD hemodynamic stenosis lesions(AUC:0.752[95%CI:0.68-0.82]vs.0.551[95%CI:0.47-0.63],p<0.001).Bland-Altman analysis showed a very mild systematic underestimation of CT-FFR values compared with FFR on a per-vessel basis(mean difference:-0.020,95%limits of agreement:-0.041 to 0.001).Conclusion The diagnostic efficacy of iFRCT in judging coronary artery functional ischemic lesions and intermediate lesions was higher than that of CCTA and ICA.Compared with gold standard FFR,the diagnosis accuracy and iFRCT of coronary artery functional ischemic lesions and intermediate lesions were high and the consistency was good.Background and Objective Instantaneous wave-free ratio(iFR)can not be affected by the systolic pressure of myocardial bridge(MB),and is more suitable for the diagnosis of myocardial bridge.The application value of instantaneous wave-free ratio based on coronary CT angiography(CCTA)(iFRCT)in myocardial bridge has not been confirmed by large sample studies.In this study,the diagnostic performance of iFRCT on coronary artery ischemic lesions in patients with MB were evaluated by using invasive fractional flow reserve(FFR)as diagnostic criteria.Materials and Methods The study included 206 cases of CCTA from Jan 2009 to Sep 2018 from 9 research centers,and 60 days of invasive coronary angiography(ICA)and invasive FFR examination.It was divided into MB group and non-MB group according to the absence of MB.The position,length,depth,muscle index and stenosis of the MB were measured on the CCTA images.According to the depth of MB,it is divided into superficial MB group(≤2mm)and deep MB group(2mm).According to the length of MB,it is divided into short MB group(≤30mm)and long MB group(30mm).Using the uFFR prototype software,iFRCT were measured based on the CCTA data of all patients,and the measured sites were at 2-4cm distal to MB.Invasive FFR≤0.80 indicate lesion specific ischemia.Based on the diagnostic criteria of invasive FFR,the diagnostic properties of different groups of iFRcT for lesion specific ischemia and the receiver operating characteristics(ROC)curves were analyzed.Bland-Altman analysis were used to analyze the consistency of iFRCT and invasive FFR in each group.Bland-Altman analysis were used to analyze the agreement between iFRCT and invasive FFRResults At the overall level,with invasive FFR as the diagnostic criterion,the sensitivity,specificity,accuracy,positive and negative predictors of iFRCT diagnosis of specific ischemia of lesions were 0.86(0.77-0.92),0.67(0.58-0.75),0.75(0.69-0.85),respectively,0.67(0.57-0.75)and 0.86(0.78-0.92).There was no significant difference in the accuracy,sensitivity,specificity,NPV and PPV of MB group and non-MB group,superficial MB group and deep MB group iFRCT in the diagnosis of lesion specific ischemia(all P0.05).There was no significant difference in the accuracy,specificity and positive predictors of the diagnosis of specific ischemia in the iFRCT of short MB group and long MB group(all P>0.05),and the sensitivity and negative predictors of the diagnosis of specific ischemia in the two groups were 1.00(0.80-1.00)and 0.80(0.56-0.93);1.00(0.87-1.00),0.85(0.65-0.95),short MB group higher than long MB Group(P=0.035,P=0.024).There was no significant difference in sensitivity,accuracy,specificity and negative predictive values between 50-69%narrow group and ≥70 stenosis group for iFRCT diagnosis of specific ischemia of lesions(all P>0.05),and the positive predictors of two groups of iFRCT in diagnosing specific ischemia of lesions were 0.40(0.33-0.81)and 0.88(0.74-0.95,P=0.001).The AUC of MB group and non-MB group,superficial MB group and deep MB group iFRCT were 0.768(0.71-0.82),0.90(0.88-0.97),0.91(0.88-0.98),0.91(0.88-0.98),0.88(0.77-0.96),0.98(0.91-1.00),0.89(0.77-0.96),0.88(0.75-0.96)and 0.96(0.91-1.00).There was no significant difference(all P>0.05)between the MB group and the non-MB group,the superficial MB group and the deep MB group iFRCT in the diagnosis of lesions of specific ischemia The AUC in the short MB group was significantly higher than that of the long MB group(P<0.001),and the)70%stenosis group was significantly higher than that of the 50-69%stenosis group(P=0.029).Bland-Altman analysis showed a very mild systematic underestimation of CT-FFR values compared with FFR on a per-vessel basis(mean difference:-0.044,95%limits of agreement:-0.061 to-0.027)Conclusion iFRCT has good consistency and accuracy in diagnosis of MB and FFR,while the diagnostic value of iFRCT for short MB group is significantly higher than that of long MB group compared with FFR.