Computed Tomography Angiography-derived Fractional Flow Research Articles

Clinical outcomes following real-world computed tomography angiography-derived fractional flow reserve testing in chronic coronary syndrome patients with calcification.

This study sought to investigate outcomes following a normal CT-derived fractional flow reserve (FFRCT) result in patients with moderate stenosis and coronary artery calcification, and to describe the relationship between the extent of calcification, stenosis, and FFRCT. Data from 975 consecutive patients suspected of chronic coronary syndrome with stenosis (30-70%) determined by computed CT angiography and FFRCT to guide downstream management decisions were reviewed. Median (range) follow-up time was 2.2 (0.5-4.2) years. Coronary artery calcium (CAC) scores were ≥400 in 25%, stenosis ≥50% in 83%, and FFRCT >0.80 in 51% of the patients. There was a lower incidence of the composite endpoint (death, myocardial infarction, hospitalization for unstable angina, and unplanned coronary revascularization) at 4.2 years in patients with any CAC and FFRCT > 0.80 vs. FFRCT ≤ 0.80 (3.9% and 8.7%, P = 0.04), however, in patients with CAC scores ≥400 the risk difference between groups did not reach statistical significance, 4.2% vs. 9.7% (P = 0.24). A negative relationship between CAC scores and FFRCT irrespective of stenosis severity was demonstrated. FFRCT shows promise in identifying patients with stenosis and calcification who can be managed without further downstream testing. Moreover, an inverse relationship between CAC levels and FFRCT was demonstrated. Studies are needed to further assess the clinical utility of FFRCT in patients with extensive coronary calcification.

Effect of Coronary Computed Tomography Angiography-Derived Fractional Flow Reserve on Physicians' Clinical Behavior - Differences Between Sites With and Without Appropriate Use Criteria as Designated by the Japanese Reimbursement System.

Background: Coronary computed tomography angiography (CCTA)-derived fractional flow reserve (FFRCT) is an established tool for identifying lesion-specific ischemia that is now approved for use by the Japanese insurance system. However, current clinical reimbursement is strictly limited to institutions with designated appropriate use criteria (AUC). This study assessed differences in physicians’ behavior (e.g., use and interpretation of FFRCT, final management) according to Japanese AUC and non-AUC site designation.Methods and Results: Of 5,083 patients in the ADVANCE Registry, 1,829 from Japan were enrolled in this study. Physicians’ behavior after interrogating CCTA and FFRCT was analyzed separately according to AUC and non-AUC site designation. Compared with AUC sites, patients referred for FFRCT from non-AUC sites had a higher rate of negative FFRCT, less severe anatomic stenosis, and a slightly lower rate of management plan reclassification (51.2% vs. 61.3%), with near-identical utility in both groups. Actual care corresponded equally well to post-FFRCT plans in both groups. The likelihood of revascularization for positive or negative FFRCT was similar between the 2 groups. Importantly, AUC and non-AUC sites were equally unlikely to revascularize patients with negative FFRCT and stenosis >50% or patients with positive FFRCT and stenosis <50%.Conclusions: Compared with AUC sites, non-AUC sites had lower disease burden and reclassification of management plans, but nearly identical clinical integration. Actual care corresponded equally well to post-FFRCT recommendations at both sites.

The impact of iterative reconstruction algorithms on machine learning-based coronary CT angiography-derived fractional flow reserve (CT-FFRML) values.

To evaluate the impact of an iterative reconstruction (IR) algorithm (advanced modeled iterative reconstruction, ADMIRE) on machine learning-based coronary computed tomography angiography-derived fractional flow reserve (CT-FFRML) measurements compared with filtered back projection (FBP). 170 plaque-containing vessels in 107 patients were included. CT-FFRML values were measured and compared among 5 imaging reconstruction algorithms (FBP and ADMIRE at strength levels of 1, 2, 3 and 5). The plaques were classified as, 'calcified" or "noncalcified" and "≥50% stenosis" or "<50% stenosis', a total of four subgroups by consensus. There were no significant differences of CT-FFRML values among the FBP and ADMIRE 1, 2, 3 and 5 groups wherever comparisons were done at the level of subgroups (P=0.676, 0.414, 0.849, 0.873, respectively) or overall (P=0.072). There were 20, 21, 19, 19 and 29 vessels with lesion-specific ischemia (CT-FFRML≤0.80) in FBP and ADMIRE 1, 2, 3 and 5 datasets, respectively, but no statistical differences were found (P=0.437). Compared with CT-FFRML value of FBP dataset, the CT-FFRML values of 9 (5.3%) vessels from 8 patients (7.5%) in ADMIRE5 dataset switched from above 0.8 to below or equal to 0.8. There were no significant differences of the CT-FFRML values among the FBP and IR image algorithms at different strength levels. However, high iterative strength level (ADMIRE 5) was not recommended, which might have an impact on diagnosis of lesion-specific ischemia, although changes only occurred in a modest number of subjects.

Coronary Computed Tomography Angiography-Derived Fractional Flow Reserve in Patients with Anomalous Origin of the Right Coronary Artery from the Left Coronary Sinus.

ObjectiveTo examine the fractional flow reserve derived from computed tomographic angiography (CT-FFR) in patients with anomalous origin of the right coronary artery from the left coronary sinus (R-ACAOS) with an interarterial course, assess the relationship of CT-FFR with the anatomical features of interarterial R-ACAOS on coronary computed tomographic angiography (CCTA), and determine its clinical relevance.Materials and MethodsNinety-four patients with interarterial R-ACAOS undergoing CCTA were retrospectively included. Anatomic features (proximal vessel morphology [oval or slit-like], take-off angle, take-off level [below or above the pulmonary valve], take-off type, intramural course, % proximal narrowing area, length of narrowing, minimum luminal area [MLA] at systole and diastole, and vessel compression index) on CCTA associated with CT-FFR ≤ 0.80 were analyzed. Receiver operating characteristic analysis was performed to describe the diagnostic performance of CT-FFR ≤ 0.80 in detecting interarterial R-ACAOS.ResultsSignificant differences were found in proximal vessel morphology, take-off level, intramural course, % proximal narrowing area, and MLA at diastole (all p < 0.05) between the normal and abnormal CT-FFR groups. Take-off level, intramural course, and slit-like ostium (all p < 0.05) predicted hemodynamic abnormality (CT-FFR ≤ 0.80) with accuracies of 0.69, 0.71, and 0.81, respectively. Patients with CT-FFR ≤ 0.80 had a higher prevalence of typical angina (29.4% vs. 7.8%, p = 0.025) and atypical angina (29.4% vs. 6.5%, p = 0.016).ConclusionTake-off level, intramural course, and slit-like ostium were the main predictors of abnormal CT-FFR values. Importantly, patients with abnormal CT-FFR values showed a higher prevalence of typical angina and atypical angina, indicating that CT-FFR is a potential tool to gauge the clinical relevance in patients with interarterial R-ACAOS.

Computed tomography angiography-derived fractional flow reserve (CT-FFR) for the detection of myocardial ischemia with invasive fractional flow reserve as reference: systematic review and meta-analysis.

A method named computed tomography angiography-derived fractional flow reserve (FFRCT) is an alternative method for detecting hemodynamically significant coronary stenosis. We carried out a meta-analysis to derive reliable assessment of the diagnostic performances of FFRCT and compare the diagnostic accuracy with CCTA using FFR as reference. We searched PubMed, EMBASE, The Cochrane Library, and Web of science for relevant articles published from January 2008 until May 2019 using the following search terms: FFRCT, noninvasive FFR, non-invasive FFR, noninvasive fractional flow reserve, non-invasive fractional flow reserve, and CCTA. Pooled estimates of sensitivity and specificity with the corresponding 95% confidence intervals (CIs) and the summary receiver operating characteristic curve (sROC) were determined. Sixteen studies published between 2011 and 2019 were included with a total of 1852 patients and 2731 vessels. The pooled sensitivity and specificity for FFRCT at the per-patient level was 89% (95% CI, 85-92%) and 71% (95% CI, 61-80%), respectively, while on the per-vessel basis was 85% (95% CI, 82-88%) and 82% (95% CI, 75-87%), respectively. No apparent difference in the sensitivity at per-patient and per-vessel level between FFRCT and CCTA was observed (0.89 versus 0.93 at per-patient; 0.85 versus 0.88 at per-vessel). However, the specificity of FFRCT was higher than CCTA (0.71 versus 0.32 at per-patient analysis; 0.82 versus 0.46 at per-vessel analysis). FFRCT obtained a high diagnostic performance and is a viable alternative to FFR for detecting coronary ischemic lesions. • Noninvasive FFRCThas higher specificity for anatomical and physiological assessment of coronary artery stenosis compared with CCTA. • Noninvasive FFRCTis a viable alternative to invasive FFR for the detection and exclusion of coronary lesions that cause ischemia.

P6183Diagnostic performance of coronary computed tomography angiography-derived fractional flow reserve in patients with acute myocardial infarction and moderate non-culprit coronary stenosis

Abstract Background Revascularisation of significant non-culprit coronary lesions (NCL) may improve clinical outcome in patients with myocardial infarction and multi vessel disease, however management of moderate NCLs is still controversial. Dobutamine stress echocardiography (DSE) and invasive fractional flow reserve (FFR) are accepted methods to detect myocardial ischemia, nevertheless coronary CT angiography-derived fractional flow reserve (CT-FFR) is a new modality, which has not been widely investigated to date in patients with NCLs. Purpose Our aim was to determine the diagnostic performance of CT-FFR compared to DSE and invasive FFR. Methods In this prospective trial, DSE, FFR and CT-FFR were performed in every patient with MI and at least one moderate NCL (30–70% diameter stenosis by visual assessment). New or worsening wall motion abnormality in at least two contiguous myocardial segments on DSE, and FFR value&lt;0.8 in invasive FFR and CT-FFR as well were determined as abnormal. In comparison, DSE and FFR were regarded as reference standard methods. Results Between March of 2017 and December of 2018, 51 patients (58.2±10.4 years, 74.5% male) were enrolled and 71 NCLs (40 LAD, 13 LCx, 18 RCA) were investigated. Dobutamine stress echocardiography, FFR and CT-FFR were positive in 30.9%, 32.3% and 22.5% of all lesions, respectively. FFR values were higher with CT-FFR compared to invasive FFR (0.85±0.11 vs. 0.83±0.08, p&lt;0.05). Compared to DSE, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and diagnostic accuracy of CT-FFR were 40.9%, 85.7%, 56.2%, 76.3% and 71.8%, respectively. The same values were 39.1%, 85.4%, 56.2%, 74.5% and 70.4% compared to invasive FFR, respectively. Correspondence of CT-FFR with DSE (k=0.29) and with FFR (k=0.27) was weak. Conclusion This is the first study that compares the three modalities in the evaluation of moderate NCLs. Our results demonstrated moderate diagnostic accuracy, excellent specificity, poor sensitivity and PPV and acceptable NPV of CT-FFR compared to DSE and FFR. At this stage, CT-FFR is probably not accurate enough to determine revascularisation strategy of moderate NCLs as a single non-invasive method.

Diagnostic Performance of Machine Learning Based CT-FFR in Detecting Ischemia in Myocardial Bridging and Concomitant Proximal Atherosclerotic Disease

BackgroundThe diagnostic performance of coronary computed tomography angiography-derived fractional flow reserve (CT-FFR) in detecting ischemia in myocardial bridging (MB) has not been investigated to date. MethodsThis retrospective multicentre study included 104 patients with left anterior descending MBs. MB was classified as either superficial or deep, short, or long, whereas all MB vessels were further divided into <50%, 50% to 69%, and ≥70% groups, according to proximal lumen stenosis on invasive coronary angiography. Diagnostic performance and receiver operating characteristics (ROC) of CT-FFR to detect lesion-specific ischemia was assessed on a per-vessel level, using invasive FFR as reference standard. Intraclass correlation coefficient (ICC) and Bland-Altman plots were used for agreement measurement. ResultsForty-eight MB vessels (46.2%) showed ischemia by invasive FFR (≤0.80). Sensitivity, specificity, and accuracy of CT-FFR to detect functional ischemia were 0.96 (0.85 to 0.99), 0.84 (0.71 to 0.92), and 0.89 (0.81 to 0.94), respectively, in all MB vessels. There were no differences in diagnostic performance between superficial and deep MB or between short and long MB (all P > 0.05). The accuracy of CT-FFR was 0.96 (0.85 to 0.99) in ≥70% stenosis, 0.82 (0.67 to 0.91) in 50% to 69% stenosis, and 0.89 (0.51 to 0.99) in <50% stenosis (P = 0.081). Bland-Altman analysis showed a slight mean difference between CT-FFR and invasive FFR of 0.014 (95% limit of agreement, –0.117 to 0.145). The ICC was 0.775 (95% confidence interval, 0.685-0.842, P < 0.001). ConclusionsCT-FFR demonstrated high diagnostic performance for identifying functional ischemia in vessels with MB and concomitant proximal atherosclerotic disease when compared with invasive FFR. However, the clinical use of CT-FFR in patients with MB needs further study for stronger and more robust results.

PATIENTS WITH ACUTE CHEST PAIN IN THE EMERGENCY ROOM: EARLY AND LATE OUTCOMES AFTER NEGATIVE CORONARY COMPUTED TOMOGRAPHY ANGIOGRAPHY-DERIVED FRACTIONAL FLOW RESERVE

Coronary computed tomography angiography-derived fractional flow reserve (FFRCT) is a validated modality for assessing lesion-specific ischemia in stable chest pain patients, but not yet validated in acute chest pain (ACP). The purpose of this study was to evaluate the long-term outcomes of patients

Approach to the Flow Rate Distribution of Coronary Branches in the Calculation of Fractional Flow Reserve

In order to improve the calculation accuracy of computed tomography angiography-derived fractional flow reserve (FFRCT), a mathematical model for setting the patient-specific flow boundary condition was proposed, in which some independent physiological parameters, such as myocardial mass, diastolic blood pressure, heart rate and vessel volume were considered. This model was employed to simulate hemodynamics in sixteen patients with coronary stenosis. The results of FFRCT demonstrated good consistency with invasively measured FFR. The diagnostic accuracy of FFRCT was 85%. The proposed model offers a new approach to improve the accuracy of FFRCT, as well as promotes the clinical application of FFRCT.

Comparison of the Diagnostic Performance of Coronary Computed Tomography Angiography-Derived Fractional Flow Reserve in Patients With Versus Without Diabetes Mellitus (from the MACHINE Consortium)

Coronary computed tomography angiography-derived fractional flow reserve (CT-FFR) is a noninvasive application to evaluate the hemodynamic impact of coronary artery disease by simulating invasively measured FFR based on CT data. CT-FFR is based on the assumption of a normal coronary microvascular response. We assessed the diagnostic performance of a machine-learning based application for on-site computation of CT-FFR in patients with and without diabetes mellitus with suspected coronary artery disease. The study population included 75 diabetic and 276 nondiabetic patients who were enrolled in the MACHINE consortium. The overall diagnostic performance of coronary CT angiography alone and in combination with CT-FFR were analyzed with direct invasive FFR comparison in 110 coronary vessels of the diabetic group and in 415 coronary vessels of the nondiabetic group. Per-vessel discrimination of lesion-specific ischemia by CT-FFR was assessed by the area under the receiver operating characteristic curves. The overall diagnostic accuracy of CT-FFR in diabetic patients was 83% and in nondiabetic patients 75% (p = 0.088), showing improvement over the diagnostic accuracy of coronary CT angiography, which was 58% and 65% (p = 0.223), respectively. In addition, the diagnostic accuracy of CT-FFR was similar between diabetic and nondiabetic patients per stratified CT-FFR group (CT-FFR < 0.6, 0.6 to 0.69, 0.7 to 0.79, 0.8 to 0.89, ≥0.9). The area under the curves for diabetic and nondiabetic patients were also comparable, 0.88 and 0.82 (p = 0.113), respectively. In conclusion, on-site machine-learning CT-FFR analysis improved the diagnostic performance of coronary CT angiography and accurately discriminated lesion-specific ischemia in both diabetic and nondiabetic patients suspected of coronary artery disease.

GW29-e1123 Computed Tomography Angiography-Derived Fractional Flow Reserve (CT-FFR) for the Detection of Myocardial Ischemia-with Invasive Fractional Flow Reserve as Reference: Systematic Review and Meta-Analysis

Carry out an updated meta-analysis to comprehensively search and review evidence available heretofore and derive reliable assessment of the diagnostic performances of computed tomography angiography-derived fractional flow reserve (CT-FFR) using fractional flow reserve (FFR) as the reference

Real-world clinical utility and impact on clinical decision-making of coronary computed tomography angiography-derived fractional flow reserve: lessons from the ADVANCE Registry.

AimsNon-invasive assessment of stable chest pain patients is a critical determinant of resource utilization and clinical outcomes. Increasingly coronary computed tomography angiography (CCTA) with selective CCTA-derived fractional flow reserve (FFRCT) is being used. The ADVANCE Registry, is a large prospective examination of using a CCTA and FFRCT diagnostic pathway in real-world settings, with the aim of determining the impact of this pathway on decision-making, downstream invasive coronary angiography (ICA), revascularization, and major adverse cardiovascular events (MACE).Methods and resultsA total of 5083 patients with symptoms concerning for coronary artery disease (CAD) and atherosclerosis on CCTA were enrolled at 38 international sites from 15 July 2015 to 20 October 2017. Demographics, symptom status, CCTA and FFRCT findings, treatment plans, and 90 days outcomes were recorded. The primary endpoint of reclassification between core lab CCTA alone and CCTA plus FFRCT-based management plans occurred in 66.9% [confidence interval (CI): 64.8–67.6] of patients. Non-obstructive coronary disease was significantly lower in ICA patients with FFRCT ≤0.80 (14.4%) compared to patients with FFRCT >0.80 (43.8%, odds ratio 0.19, CI: 0.15–0.25, P < 0.001). In total, 72.3% of subjects undergoing ICA with FFRCT ≤0.80 were revascularized. No death/myocardial infarction (MI) occurred within 90 days in patients with FFRCT >0.80 (n = 1529), whereas 19 (0.6%) MACE [hazard ratio (HR) 19.75, CI: 1.19–326, P = 0.0008] and 14 (0.3%) death/MI (HR 14.68, CI 0.88–246, P = 0.039) occurred in subjects with an FFRCT ≤0.80.ConclusionsIn a large international multicentre population, FFRCT modified treatment recommendation in two-thirds of subjects as compared to CCTA alone, was associated with less negative ICA, predicted revascularization, and identified subjects at low risk of adverse events through 90 days.

Noninvasive numerical simulation of coronary fractional flow reserve based on lattice Boltzmann method

In order to investigate the application of lattice Boltzmann method (LBM) in the numerical simulation of computed tomography angiography-derived fractional flow reserve (FFR CT), an idealized narrowed tube model and two coronary stenosis arterymodels are studied. Based on the open source code library (Palabos), the relative algorithm program in the development environment (Codeblocks) was improved. Through comparing and analyzing the results of FFR CT which is simulated by LBM and finite element analysis software ANSYS, and the feasibility of the numerical simulation of FFR CT by LBM was verified . The results show that the relative error between the results of LBM and finite element analysis software ANSYS is about 1%, which vertifies the feasibility of simulating the coronary FFR CT by LBM. The simulation of this study provides technical support for developing future FFR CT application software, and lays the foundation for the calculation of clinical FFR CT.

Técnicas de imagen híbridas en cardiopatía isquémica

Hybrid imaging for ischemic heart disease refers to the fusion of information from a single or usually from multiple cardiovascular imaging modalities enabling synergistic assessment of the presence, the extent, and the severity of coronary atherosclerotic disease along with the hemodynamic significance of lesions and/or with evaluation of the myocardial function. A combination of coronary computed tomography angiography with myocardial perfusion imaging, such as single-photon emission computed tomography and positron emission tomography, has been adopted in several centers and implemented in international coronary artery disease management guidelines. Interest has increased in novel hybrid methods including coronary computed tomography angiography-derived fractional flow reserve and computed tomography perfusion and these techniques hold promise for the imminent diagnostic and management approaches of patients with coronary artery disease. In this review, we discuss the currently available hybrid noninvasive imaging modalities used in clinical practice, research approaches, and exciting potential future technological developments.

Hybrid Imaging in Ischemic Heart Disease

Hybrid imaging for ischemic heart disease refers to the fusion of information from a single or usually from multiple cardiovascular imaging modalities enabling synergistic assessment of the presence, the extent, and the severity of coronary atherosclerotic disease along with the hemodynamic significance of lesions and/or with evaluation of the myocardial function. A combination of coronary computed tomography angiography with myocardial perfusion imaging, such as single-photon emission computed tomography and positron emission tomography, has been adopted in several centers and implemented in international coronary artery disease management guidelines. Interest has increased in novel hybrid methods including coronary computed tomography angiography-derived fractional flow reserve and computed tomography perfusion and these techniques hold promise for the imminent diagnostic and management approaches of patients with coronary artery disease. In this review, we discuss the currently available hybrid noninvasive imaging modalities used in clinical practice, research approaches, and exciting potential future technological developments.