The Clinical Application Of Dynamic CT Myocardial Perfusion In Patients With Coronary Artery Disease

Part 1 Diagnostic performance of dynamic CT myocardial perfusion in patients with obstructive coronary artery diseaseObjectives:Obstructive coronary artery disease(CAD)is a common condition that can lead to myocardial ischemia and subsequent adverse outcomes.The detection of hemodynamically significant ischemia is crucial for guiding clinical decision-making.Dynamic CT myocardial perfusion(CTP)is a new noninvasive functional imaging modality.The aim of this study was to evaluate the diagnostic efficacy of dynamic CTP in identifying lesion-specific ischemia in patients with obstructive CAD,using invasive coronary angiography(ICA)and fractional flow reserve(FFR)as reference standards.Material and methods:Patients with CAD who underwent coronary CT angiography(CCTA),dynamic CTP,and subsequently ICA within 4 weeks after CCTA were retrospectively collected between September 2018 and September 2021 with at least one vessel with≥v50%stenosis on CCTA.Absolute myocardial blood flow(MBF)and relative MBF were calculated.vessels with ICA stenosis of 50%-89%received FFR measurements;lesion-specific ischemia was defined as ICA stenosis≥ 90%or FFR≤0.8.Results:A total of 61 vessels from 48 patients were eventually included in the analysis,and ICA and FFR identified lesion-specific ischemia in 51 vessels from 41 patients.According to the Youden index,the optimal cutoff values for absolute MBF and relative MBF were 99.8 mL/1 00 mL/min and 0.78,respectively.Analysis by vessel level showed an accuracy of 88.5%and 86.9%for absolute MBF and relative MBF.respectively,which were both significantly higher than CCTA stenosis≥ 70%(73.8%)(P<0.05),but the difference between them was not statistically significant(P=0.803).The sensitivity(88.2%;88.2%)and specificity(90.0%;80.0%)of absolute MBF and relative MBF were similar and both were higher than CCTA stenosis≥ 70%(sensitivity:76.5%;specificity:60.0%),but the difference was not statistically significant(P>0.05).According to the analysis of receiver operating characteristic curves,absolute MBF and relative MBF possessed high area under the curve(0.957;0.914)with no statistically significant difference(P=0.361),both significantly higher than CCTA stenosis≥ 70%(0.682)(P<0.05).The median dose length products of dynamic CTP and CCTA were 318 mGy·cm and 377 mGy·cm,respectively.Conclusion:Dynamic CTP has high diagnostic value in identifying lesion specific ischemia in patients with obstructive CAD.There was no significant difference in diagnostic performance between absolute MBF and relative MBF.Part 2 Prognostic value of myocardial blood flow quantified with stress dynamic computed tomography perfusion imaging for major adverse cardiac events in patients with coronary artery diseaseObjectives:The aim of this study was to evaluate the incremental prognostic value of stress dynamic computed tomography myocardial perfusion(CTP)physiologic assessment over coronary computed tomography angiography(CCTA)anatomic assessment for major adverse cardiac events(MACE)in patients with suspected or known coronary artery disease(CAD).Material and methods:Consecutive patients with suspected or known CAD who underwent clinically indicated CCTA and stress dynamic CTP were included.MACE consisted of all-cause death,nonfatal myocardial infarction(MI),hospitalization for unstable angina,and percutaneous coronary intervention or coronary artery bypass grafting 90-days after imaging test.Obstructive stenosis was defined as left main≥ 50%or other coronary segments≥ 70%.A summed stress score(SSS)was calculated by adding scores of all myocardial segments according to normalized myocardial blood flow(MBF)values.Ischemic perfusion defect(IPD)was defined as SSS≥ 4.Results:A total of 350 patients were included(mean age 55.7 ± 14.4 years,32%females).After a median follow-up of 30 months,50(14%)patients experienced MACE.Multivariate analysis showed that IPD significantly associated with hazards for MACE(HR:5.161,95%CI:2.498-10.660,P<0.001)and improved discrimination(Harrel’s C:0.800,P<0.001)in models with CCTA obstructive stenosis.Results were consistent using subgroups of alternate definitions of obstructive stenosis.The mean dose-length product of CCTA and dynamic CTP were 365 mGy·cm and 329 mGy·cm,respectively.Conclusions:In patients with suspected or known CAD,IPD assessed by stress dynamic CTP has incremental prognostic value over stenosis assessed by CCTA alone in predicting the incidence of cardiovascular outcomes.Part 3 Prognostic value of myocardial flow reserve assessed by dynamic computed tomography perfusion imaging in patients with suspected or known coronary artery diseaseObjectives:The objective of this study was to assess whether myocardial flow reserve(MFR),evaluated through rest/stress dynamic computed tomography myocardial perfusion(CTP)assessment,provides incremental prognostic value over coronary computed tomography angiography(CCTA)assessment for major adverse cardiac events(MACE)in patients with suspected or known coronary artery disease(CAD).Material and methods:The study included 296 consecutive patients who underwent both CCTA and rest/stress CTP assessment for suspected or known CAD between 2019 and 2021,and 289(98%)of them completed follow-up(median 22.4 months).The primary endpoint was MACE,defined as a composite of all-cause mortality,nonfatal myocardial infarction,unstable angina requiring hospitalization,or late revascularization(>90 days after CCTA).Obstructive stenosis was defined as left main≥50%or other coronary segments≥70%.MFR was calculated as the ratio of stress to rest myocardial blood flow(MBF)for the entire left ventricle.Results:During the follow-up period,31 patients(14%)(29.4 events per 1000 person-year)experienced MACE.Multivariate analysis showed that every 0.1 unit decrease in MFR significantly associated with hazards for MACE(HR:1.224,95%CI:1.080-1.387,P=0.002).The addition of MFR assessment to CCTA significantly improved the discriminatory(C-statistic:0.830 vs.0.793,P=0.001)and reclassification(categorical net classification index(NRI)=0.151,P<0.001;continuous NRI=0.763,P<0.001;integrated discrimination index(IDI)=0.042,P=0.014)ability for MACE compared to CCTA alone.Conclusions:MFR provides incremental prognostic value over CCTA assessment for predicting MACE in patients with suspected or known CAD.The addition of MFR assessment to CCTA improves the discriminatory and reclassification ability for MACE and may help guide clinical decision-making for the management of these patients.