Efficacy And Influencing Factors Of CT-based Fractional Flow Reserve In The Diagnosis Of Myocardial Ischemia

Part 1 Diagnostic Performance of CT FFR with Computational Fluid Dynamics Algorithm for identifying ischemia:Results From CT-FFR-CHINA TrialObjectives:To assess the diagnostic performance of computed tomography derived fractional flow reverse(CT-FFR)obtained by computational fluid dynamics(CFD)algorithm to detect ischemia,using fractional flow reverse(FFR)as a reference.Methods:This prospective clinical trial analyzed 317 patients with clinically suspected coronary artery disease from 5 centers between November 2018,and March 2020.All the patients underwent coronary computed tomography angiography(CCTA),CT-FFR,invasive coronary angiography(ICA),and FFR in a week.CT-FFR were obtained from a CFD algorithm(Heartcentury Co.,Ltd,Beijing,China).With FFR as reference standard,the diagnostic accuracy and diagnostic performance(sensitivity,specificity,positive predictive value[PPV],and negative predictive value[NPV])of CT-FFR(?0.8),and CCTA(? 50%stenosis)for identifying ischemia was assessed.The area under receiver operator characteristic curve(AUC)of CT-FFR and CCTA was also compared.The diagnostic performance of CT-FFR for coronary intermediate stenosis(30%-70%)and"gray zone" lesions(FFR 0.76-0.80)was further investigated.Results:A total of 366 target vessels in 317 patients were analyzed in this study.There was a good agreement of CT-FFR with invasive FFR on per-vessel level.On a per-vessel level,the accuracy,sensitivity,specificity,PPV,NPV,and AUC of CT-FFR(<0.8)and CCTA(>50%stenosis)in identifying ischemia were 88.8%,89.9%,87.8%,87.3%,91.1%,0.89,and 60.4%,89.3%,35.5%,54.3%,79.5%,0.62,respectively.On aper-patient level,the diagnostic accuracy,sensitivity,specificity,PPV,NPV,and AUC of CT-FFR and CCTA,were 89.9%,89.9%,89.8%,89.9%,89.8%,0.89,and 63.4%,88.9%,37.2%,59.3%,76.3%,0.64.The diagnostic accuracy of CT-FFR for "gray zone" lesions(FFR:0.76-0.80)was 80%.The diagnostic accuracy,sensitivity,specificity,PPV,NPV and AUC of CT-FFR for coronary intermediate lesions were 91.7%,88.3%,93.5%,88.3%,93.5%,0.90.And diagnostic accuracy of CT-FFR for "gray area" lesions was 80%.Conclusion:CT-FFR based on CFD model provides better diagnostic performance for lesion-specific ischemia than CCTA.For "gray zone" and intermediate stenosis lesions,the diagnostic accuracy of CT-FFR is high.Part 2 Effect of coronary calcification severity on diagnostic performance of CT-FFR with computational fluid dynamics:results from CT-FFR CHINA trialObjectives:To investigate the effect of coronary calcification severity on the measurements and diagnostic performance of computed tomography derived fractional flow reverse(FFR;CT-FFR).Methods:This study enrolled a total of 305 patients with evaluable coronary calcification score from CT-FFR CHINA trial.All patients underwent coronary CT angiography(CCTA),CT-FFR and FFR in a week.The enrolled patient and target vessels were classified into 4 categories:CAC=0,>0 to<100,?100 to<400,and ?400.The measured CT-FFR values,accuracy,and diagnostic performance of CT-FFR for discriminating ischemia were analyzed across all coronary artery calcification(CAC)score categories(CAC=0,>0 to<100,? 100 to<400,and ?400)on both per-vessel and per-patient levels,with FFR as reference standard.Results:305 patients(210 men,59.2±9.7 years)with 348 target vessels were analyzed.Absolute difference of CT-FFR and FFR values tended to elevate with increased CAC scores(CAC=0:0.09±0.10;CAC>0 to<100:0.06±0.06;CAC ? 100 to<400:0.09±0.10;CAC ? 400:0.11±0.13;p=0.246).The accuracy,sensitivity,specificity,and AUC of CT-FFR to detect lesion-specific ischemia were not significantly different across CAC score categories on both per-vessel and per-patient levels.Although the largest value of area under receiver operating characteristics curve(AUC)was observed in CAC? 400 group(per-vessel level,CAC?400:AUC=0.98[95%CI:0.84-1.00];per-patient level,CAC?400:AUC=0.92[95%CI:0.83-0.98]).Conclusion:The deviation of CT-FFR values tended to elevate with increased CAC scores.However,coronary calcification severity has no significant influence on the diagnostic performance of CT-FFR.Clinical Trial Registration:https://clinicaltrials.gov;NCT03692936.Part 3 Effect of preprocedural nitroglycerin administration onthe diagnostic performance of fractional flow reverse derived from computed tomography angiographyObjectives:To investigate the effect of nitroglycerin administration prior to coronary CT on the calculation and diagnostic performance of machine-learning based fractional flow reverse derived from computed tomography angiography(FFR;CT-FFR).Methods:In this retrospective study,107 consecutive patients clinically suspected of coronary artery disease with nitroglycerin administration prior to CCTA from January 2019 to December 2019 were matched to 107 patients without nitroglycerin between January 2016 and December 2016.All included patients underwent CCTA and FFR in a month.Vessel-based and patient-based accuracy and diagnostic performance of CT-FFR for identifying ischemia were compared between nitroglycerin and non-nitroglycerin groups,as well as image quality and coronary evaluability.Results:A total of 214 patients(56.1 ± 8.9 years,155 men)with 237 target vessels were analyzed,including 120 vessels in nitroglycerin group and 11 7 in non-nitroglycerin group.The measurement bias(compared with 0)of CT-FFR in the nitroglycerin group was smaller than that in the non-nitroglycerin group(-0.05 ± 0.13,0.01 ± 0.12,=0.007).On a per-vessel basis,the accuracy of CT-FFR was significantly higher in nitroglycerin group(80.0%vs.68.4%,p=0.041).On a per-patient basis,nitroglycerin administration significantly improved the accuracy(83.2%vs.68.2%,p=0.011),specificity(82.7%vs.61.9%,p=0.014),PPV(83.6%vs.58.4%,p=0.004),and AUC(0.83 vs.0.71,p=0.03)of CT-FFR.Diameters of 4 main epicardial coronary artery(left main:4.3 mm vs.3.8mm;left anterior descending:3.1 mm vs.2.9 mm;left circumflex artery:2.9 mm vs.2.7 mm;right coronary artery:3.7 mm vs.3.4 mm)and number of evaluable coronary arteries(11.0 vs.8.0)were markedly larger in nitroglycerin group(all p<0.05).Conclusion:Nitroglycerin administration prior to coronary CT angiography has a positive effect on diagnostic performance of CT derived fractional flow reserve,due to significant vessel dilation and improved evaluability of coronary arteries.