The Diagnostic And Prognostic Value Of Fractional Flow Reserve Derived From CT In Patients With Coronary Artery Disease

Background: Coronary artery disease(CAD)requires simultaneous assessment of anatomical stenosis and physiologic ischemic status.Fractional flow reserve(FFR)is the gold standard for diagnosing CAD with lesion-specific ischemia,but the invasiveness and expensive pressure guide wire limit its clinical application.CTderived FFR(fractional flow reserve derived from FFRCT)has been shown to be highly consistent with FFR.However,current FFRCT-related studies mostly focus on CAD patients before revascularization,and rarely evaluate the hemodynamic status after revascularization.This study intends to analyze the FFRCT based on an novel algorithm of transluminal attenuation gradient(TAG),to explore its diagnostic and prognostic analysis in patients with obstructive CAD,and to evaluate the hemodynamic status of CAD after revascularization.to evaluate.The full text is divided into three parts.Part I: Correlation between CT-derived fractional flow reserve and the prognosis of patients with single-vessel obstructive stenosis.Objective: This study aimed to investigate the association between FFRCT and prognosis in patients with single-vessel coronary obstructive stenosis.Methods: Retrospective analysis of clinical and CCTA data in CAD patients who underwent coronary CT angiography(CCTA)between January 1,2016,and December 31,2020 and were confirmed as single-vessel coronary obstructive stenosis(stenosis degree ≥50%).The patients were divided into conservative treatment group and PCI group according to whether they underwent percutaneous coronary intervention(PCI).The baseline clinical data of the two groups were balanced by propensity score matching(PSM),and the TAG algorithm was used.FFRCT analysis was performed on LAD、LCX and RCA.The end point of the study was the occurrence of major adverse cardiac and cerebrovascular events(MACCE).Univariate analysis was performed on the occurrence of MACCE,and variables with P<0.2 were included in multivariate Cox regression analysis.Results: After PSM,503 patients with single-vessel coronary obstructive stenosis were finally included,including 315 patients in the conservative group and 188 patients in the PCI group.The difference in FFRCT was statistically significant(all P<0.05),and the incidence of MACCE in the PCI group was significantly lower than that in the conservative group(P<0.05).Cox regression analysis showed unstable angina pectoris(hazard ratio(HR),3.165;95% confidence interval(CI),2.087-4.800,P<0.001),FFRCT≤0.80(HR,1.632;95%)CI,1.095-2.431;P=0.016)was an independent risk factor for MACCE,while PCI treatment(HR,0.481;95% CI,0.305-0.758;P=0.002)was an independent protective factor for good prognosis.Part II: To explore the value of FFRCT in evaluating the hemodynamic changes before and after stent implantation in patients with CAD.Objective: This study aimed to noninvasively assess the hemodynamic changes before and after stent implantation in CAD patients using FFRCT.Methods: Patients who underwent coronary stent implantation from January 1,2013 to December 31,2020 and underwent CCTA within30 days before and 90 days after surgery were collected.The u CT-FFR software was used to calculate the FFRCT values and differences of the three major coronary arteries of each patient before and after stent implantation,which were expressed as pre-FFRCT,post-FFRCT and(35)FFRCT,respectively.Obstructive coronary stenosis was defined as a degree of stenosis ≥50% according to CCTA.According to pre-FRCT≤0.80,the patients were divided into non-ischemia group and ischemia group.The endpoint was MACCE.Kaplan-Meier survival analysis was used to compare the survival rate between the non-ischemia and ischemic groups.Results: A total of 230 patients were finally included,including 172 males(74.8%)and 58 females(25.2%),with an average age of 65.0±10.6 years.Of the 230 patients,83(36.1%)in non-ischemia group and 147(63.9%)in ischemia group.A total of 314(45.5%)of the 690 vessels were stented,and the pre-FFRCT in the obstructive stenosis group was significantly lower than that in the non-obstructive stenosis group(Z=-12.484,P<0.01).There was no significant difference in post-FFRCT(Z=-1.900,P=0.057),while(35)FFRCT was significantly higher than that in the non-obstructive stenosis group(Z=-10.242,P<0.001).The preFFRCT and post-FFRCT in the preoperative ischemia group were significantly lower than those in the non-ischemia group,and(35)FFRCT was significantly higher than that in the non-ischemia group,Z=-15.223,-2.473,13.305,all P<0.05.The median followup time was 27(15,47)months,a total of 63 cases(27.4%)developed MACCE.The overall incidence of MACCE at 1,3,and 5 years was 1.3%,21.2%,and 47.5%,respectively.There was no significant difference in the survival rate between the nonischemia group and the ischemia group(P=0.208).Part III: Correlation between simulated blood flow and intraoperative blood flow after coronary artery bypass graft based on computational fluid dynamics.Objective:This study aimed to explore the feasibility of evaluating simulated blood flow of grafted vessels after coronary artery bypass grafting(CABG)based on computational fluid dynamics(CFD)analysis,and to analyze its Correlation with intraoperative blood flow.Methods: From March 2020 to December 2020,patients with coronary obstructive stenosis who were scheduled to undergo CABG were prospectively enrolled.All patients underwent CCTA 30 days before and 90 days after surgery.The CFD model based on the TAG algorithm was used to analyze the preoperative and postoperative CCTA of CABG,to calculate the simulated blood flow of the preoperative coronary FFRCT and postoperative graft,and to analyze the correlation with the intraoperative blood flow.Patients were divided into systolic and diastolic groups according to the CCTA images after CABG were divided into two groups according to,and the blood flow of grafted vessels was compared between the two groups.Results: A total of 8patients were included,with 11 grafted vessels.Among them,there were 7 males(87.5%)and 1 female(12.5%),with an average age of 68.3±6.8 years.All grafts were not obstructive during the 1-year follow-up.The simulated blood flow calculation of 1artery after grafting failed,the intraoperative blood flow of the remaining 10 grafted vessels was 83.7±60.9 ml/min,and the simulated blood flow of the postoperative graft was 63.3±36.9 ml/min.The median flow rate change rate was-16%(-33.3%,18.8%).There was a significant positive correlation between the simulated blood flow of the grafted blood vessels after surgery and the intraoperative blood flow,and the correlation coefficient was 0.954.There was no significant difference in the intraoperative blood flow of the grafted blood vessel,the simulated blood flow of the grafted blood vessel after the operation,and the change rate of the blood flow of the grafted blood vessel between the two groups in the systolic and diastolic periods(all P>0.05).Conclusions: 1.Unstable angina pectoris and FFRCT≤0.80 are independent risk factors for MACCE in single-vessel coronary obstructive stenosis,and PCI therapy is an independent protective factor for good prognosis.2.Compared with the nonobstructive stenosis group,the pre-FFRCT of the obstructive stenosis group was significantly lower,and the(35)FFRCT was significantly higher,and there was no significant difference in post-FFRCT between the two groups.Compared with the preoperative ischemia group,the pre-FFRCT and post-FFRCT in the preoperative ischemia group were significantly lower,and(35)FFRCT was significantly higher.The incidence of short-term MACCE in patients after stent implantation was lower,but the incidence of mid-and long-term MACCE was higher.3.CFD based on TAG algorithm can be used to evaluate the simulated blood flow of grafted vessels after CABG,and the simulated blood flow of postoperative grafts is significantly positively correlated with the real flow of grafted vessels during operation.