Tomography-derived Fractional Flow Reserve Research Articles

Non-invasive physiological assessment of coronary artery obstruction on coronary computed tomography angiography.

Computed tomography-derived fractional flow reserve (CT-FFR) enhances the specificity of coronary computed tomography angiography (CCTA) to that of the most specific non-invasive imaging techniques, while maintaining high sensitivity in stable coronary artery disease (CAD). As gatekeeper for invasive coronary angiography (ICA), use of CT-FFR results in asignificant reduction of negative ICA procedures and associated costs and complications, without increasing cardiovascular events. It is expected that CT-FFR algorithms will continue to improve, regarding accuracy and generalisability, and that introduction of new features will allow further treatment guidance and reduced invasive diagnostic testing. Advancements in CCTA quality and artificial intelligence (AI) are starting to unfold the incremental diagnostic and prognostic capabilities of CCTA's attenuation-based images in CAD, with future perspectives promising additional CCTA parameters which will enable non-invasive assessment of myocardial ischaemia as well as CAD activity and future cardiovascular risk. This review discusses practical application, interpretation and impact of CT-FFR on patient care, and how this ties into the CCTA 'one stop shop' for coronary assessment and patient prognosis. In this light, selective adoption of the most promising, objective and reproducible techniques and algorithms will yield maximal diagnostic value of CCTA without overcomplicating patient management and guideline recommendations.

Automated CT-FFR model for diagnosing hemodynamically significant coronary artery disease. A prospective validation study

Abstract Aims To assess the diagnostic performance of a novel computed tomography-derived fractional flow reserve (CT-FFR) algorithm and to compare its accuracy at three predefined sites: a) at the location of invasive fractional flow reserve (FFR) measurements (CT-FFRatloc), b) at selected sites determined by an automated module integrated within the algorithm (CT-FFRauto), and c) distally in the vessel (CT-FFRdistal). Methods and results We prospectively recruited 108 consecutive patients with stable symptoms of coronary artery disease (CAD) and at least one suspected obstructive lesion on coronary computed tomography angiography (CCTA). CT-FFR was validated against invasive FFR as gold standard using an FFR≤ 0.80 to define myocardial ischemia. CT-FFRatloc showed good correlation with invasive FFR (r=0.67) and improved the ability to detect myocardial ischemia compared to CCTA at both lesion (AUC 0.83 vs 0.65, P<0.001) and patient level (AUC 0.87 vs 0.74, P=0.007). CT-FFRauto demonstrated similar diagnostic accuracy to CT-FFRatloc and significantly improved specificity compared to CT-FFRdistal (86% vs 49%, P<0.001). High end CT quality improved the diagnostic performance of CT-FFRauto, demonstrating an AUC of 0.92, similarly, the performance was improved in patients with low-to-intermediate CAC score with an AUC of 0.88. Conclusion Implementing an automated module to determine the site of CT-FFR evaluations was feasible and CT-FFRauto demonstrated comparable diagnostic accuracy to CT-FFRatloc when assessed against invasive FFR. Both CT-FFRatloc and CT-FFRauto improved the diagnostic performance compared to CCTA and improved specificity compared to CT-FFRdistal. High end CT quality and low-to-intermediate calcium burden improved the diagnostic performance of our algorithm. ClinicalTrials.gov id NCT03045601

The Effect of Severe Coronary Calcification on Diagnostic Performance of Computed Tomography-Derived Fractional Flow Reserve Analyses in People with Coronary Artery Disease.

Negative CCTA can effectively exclude significant CAD, eliminating the need for further noninvasive or invasive testing. However, in the presence of severe CAD, the accuracy declines, thus necessitating additional testing. The aim of our study was to evaluate the diagnostic performance of noninvasive cFFR derived from CCTA, compared to ICA in detecting hemodynamically significant stenoses in participants with high CAC scores (>400). This study included 37 participants suspected of having CAD who underwent CCTA and ICA. CAC was calculated and cFFR analyses were performed using an on-site machine learning-based algorithm. Diagnostic accuracy parameters of CCTA and cFFR were calculated on a per-vessel level. The median total CAC score was 870, with an IQR of 642-1370. Regarding CCTA, sensitivity and specificity for RCA were 60% and 67% with an AUC of 0.639; a LAD of 87% and 50% with an AUC of 0.688; an LCX of 33% and 90% with an AUC of 0.617, respectively. Regarding cFFR, sensitivity and specificity for RCA were 60% and 61% with an AUC of 0.606; a LAD of 75% and 54% with an AUC of 0.647; an LCX of 50% and 77% with an AUC of 0.647. No significant differences between AUCs of coronary CTA and cFFR for each vessel were found. Our results showed poor diagnostic accuracy of CCTA and cFFR in determining significant ischemia-related lesions in participants with high CAC scores when compared to ICA. Based on our results and study limitations we cannot exclude cFFR as a method for determining significant stenoses in people with high CAC. A key issue is accurate and detailed lumen segmentation based on good-quality CCTA images.

Computed Tomography-Derived Fractional Flow Reserve Versus Usual Care Strategy to Guide the Management of Patients With Stable Coronary Artery Disease: A Meta-Analysis and Systematic Review

Computed Tomography-Derived Fractional Flow Reserve Versus Usual Care Strategy to Guide the Management of Patients With Stable Coronary Artery Disease: A Meta-Analysis and Systematic Review

Additional prognostic impact of plaque characterization with on-site CT-derived fractional flow reserve in coronary CT angiography

BackgroundOn-site computed tomography-derived fractional flow reserve (CT-FFR) is a feasible method for examining lesion-specific ischemia, and plaque analysis of coronary CT angiography (CCTA) is useful for predicting future cardiac events. However, their utility and association on a per-vessel level remain unclear. MethodsWe analyzed vessels showing 50–90 % stenosis on CCTA where planned revascularization was not performed after CCTA within 90 days. Relevant features, including CT-FFR and the plaque burden [necrotic core to the total plaque volume (% necrotic core), and non-calcified plaque (NCP) to vessel volume (% NCP)] using a novel algorithm for analyzing plaque to predict vessel-oriented composite outcomes (VOCO), including cardiac death, non-fatal myocardial infarction, and unplanned vessel-related revascularization, were assessed. ResultsIn 256 patients (68.7 ± 9.4 years; 73.8 % male) with 354 vessels (10.5 % CT-FFR ≤ 0.80), VOCO occurred in 24 vessels (6.8 %) during a median follow-up of 3.6 years. Multivariable Cox analysis revealed CT-FFR ≤ 0.80 had the pronounced impact on VOCO, and moreover, higher % necrotic core and % NCP were independently associated with VOCO [adjusted hazard ratio 3.43 (95 % confidence interval 1.42–8.29) and 4.05 (1.19–13.71), respectively], especially for vessels with CT-FFR > 0.80. ConclusionsIn vessels without planned revascularization, per-vessel CT-FFR ≤ 0.80 was the notable predictor of future cardiac events. Additionally, necrotic core volume and NCP were identified as independent predictors along with CT-FFR.

Utilization of coronary computed tomography angiography and computed tomography-derived fractional flow reserve in a critical limb-threatening ischemia cohort

Utilization of coronary computed tomography angiography and computed tomography-derived fractional flow reserve in a critical limb-threatening ischemia cohort

The Correlation between Region-specific Epicardial Adipose Tissue and Myocardial Ischemia Defined by CT-FFR in Type 2 Diabetes Mellitus Patients.

Epicardial Adipose Tissue (EAT) accumulation is closely associated with the presence and severity of coronary artery disease (CAD), myocardial ischemia, plaque vulnerability, and major adverse cardiovascular events. The aim of this study was to investigate the correlation between myocardial ischemia defined by computed tomography-derived fractional flow reserve (CT-FFR) and region-specific EAT in patients with type 2 diabetes mellitus (T2DM). Between January 2022 and May 2023, 200 T2DM patients were randomly selected from the Department of Endocrinology in The Central Hospital of Wuhan. These patients were divided into two groups based on myocardial ischemia defined by CT-FFR: myocardial ischemia group (152 cases) and control group (48 cases). Both groups of patients used a post-treatment workstation to measure the thickness of region-specific EAT. Receiver operating characteristic (ROC) curve analysis and binary logistic regression were used to evaluate the correlation between various parameters and myocardial ischemia. Patients in the myocardial ischemia group had significantly higher values of age, male gender, systolic blood pressure, total cholesterol, triglycerides, LDL, HDL, fasting blood glucose, fasting insulin, HOMA-IR, EAT thickness in right ventricular wall, left atrioventricular groove, and superior and inferior interventricular groove. ROC curve analysis results showed that EAT thickness in the left atrioventricular groove had the largest area under the ROC curve for diagnosing myocardial ischemia (0.837 [95% CI 0.766-0.865]; P < 0.001). Binary logistic regression analysis showed that EAT thickness in the left atrioventricular groove was an independent risk factor for myocardial ischemia in patients with T2DM (P < 0.05). The EAT thickness in the left atrioventricular groove is an independent risk factor for myocardial ischemia in patients with T2DM. Adipose tissue in the left atrioventricular groove region plays a major role in EAT-mediated CAD.

Comparison of machine learning-based CT fractional flow reserve with cardiac MR perfusion mapping for ischemia diagnosis in stable coronary artery disease.

To compare the diagnostic performance of machine learning (ML)-based computed tomography-derived fractional flow reserve (CT-FFR) and cardiac magnetic resonance (MR) perfusion mapping for functional assessment of coronary stenosis. Between October 2020 and March 2022, consecutive participants with stable coronary artery disease (CAD) were prospectively enrolled and underwent coronary CTA, cardiac MR, and invasive fractional flow reserve (FFR) within 2weeks. Cardiac MR perfusion analysis was quantified by stress myocardial blood flow (MBF) and myocardial perfusion reserve (MPR). Hemodynamically significant stenosis was defined as FFR ≤ 0.8 or > 90% stenosis on invasive coronary angiography (ICA). The diagnostic performance of CT-FFR, MBF, and MPR was compared, using invasive FFR as a reference. The study protocol was completed in 110 participants (mean age, 62years ± 8; 73 men), and hemodynamically significant stenosis was detected in 36 (33%). Among the quantitative perfusion indices, MPR had the largest area under receiver operating characteristic curve (AUC) (0.90) for identifying hemodynamically significant stenosis, which is in comparison with ML-based CT-FFR on the vessel level (AUC 0.89, p = 0.71), with comparable sensitivity (89% vs 79%, p = 0.20), specificity (87% vs 84%, p = 0.48), and accuracy (88% vs 83%, p = 0.24). However, MPR outperformed ML-based CT-FFR on the patient level (AUC 0.96 vs 0.86, p = 0.03), with improved specificity (95% vs 82%, p = 0.01) and accuracy (95% vs 81%, p < 0.01). ML-based CT-FFR and quantitative cardiac MR showed comparable diagnostic performance in detecting vessel-specific hemodynamically significant stenosis, whereas quantitative perfusion mapping had a favorable performance in per-patient analysis. ML-based CT-FFR and MPR derived from cardiac MR performed well in diagnosing vessel-specific hemodynamically significant stenosis, both of which showed no statistical discrepancy with each other. • Both machine learning (ML)-based computed tomography-derived fractional flow reserve (CT-FFR) and quantitative perfusion cardiac MR performed well in the detection of hemodynamically significant stenosis. • Compared with stress myocardial blood flow (MBF) from quantitative perfusion cardiac MR, myocardial perfusion reserve (MPR) provided higher diagnostic performance for detecting hemodynamically significant coronary artery stenosis. • ML-based CT-FFR and MPR from quantitative cardiac MR perfusion yielded similar diagnostic performance in assessing vessel-specific hemodynamically significant stenosis, whereas MPR had a favorable performance in per-patient analysis.

A meta-analysis comparing the diagnostic performance of computed tomography-derived fractional flow reserve and coronary computed tomography angiography at different levels of coronary artery calcium score.

The impact of coronary calcification on the diagnostic accuracy of computed tomography-derived fractional flow reserve (CT-FFR) and coronary computed tomography angiography (CCTA) remains a crucial consideration. This meta-analysis aims to compare the diagnostic performance of CT-FFR and CCTA at different levels of coronary artery calcium score (CACS). We searched PubMed, Embase, and the Cochrane Library for relevant articles on CCTA, CT-FFR, and invasive fractional flow reserve (FFR). Ten studies were included to evaluate the diagnostic performance of CT-FFR and CCTA at the per-patient and per-vessel levels in four CACS groups. Invasive FFR was used as the reference standard. Except for the CACS ≥ 400 group, the AUC of CT-FFR was higher than those of CCTA in other subgroups of CACS (in CACS < 100 (per-patient, 0.9 (95% CI 0.87-0.92) vs. 0.32 (95% CI 0.28-0.36); per-vessel, 0.92 (95% CI 0.89-0.94) vs. 0.66 (95% CI 0.62-0.7); both p < 0.001), CACS ≥ 100 (per-patient, 0.86 (95% CI 0.82-0.88) vs. 0.44 (95% CI 0.4-0.48); per-vessel, 0.88 (95% CI 0.85-0.9) vs. 0.51 (95% CI 0.46-0.55); both p < 0.001), and CACS < 400 (per-patient, 0.9 (95% CI 0.87-0.93) vs. 0.74 (95% CI 0.7-0.78), p < 0.001; per-vessel, 0.8 (95% CI 0.76-0.83) vs. 0.74 (95% CI 0.7-0.78); p = 0.02)). CT-FFR demonstrates superior diagnostic performance in low CACS groups (CACS < 400) than CCTA in detecting hemodynamic stenoses in patients with coronary artery disease (CAD). Computed tomography-derived fractional flow reserve might be utilized to determine the necessity of invasive coronary angiography in coronary artery disease patients with coronary artery calcium score < 400. • There is a lack of meta-analysis comparing the diagnostic performance of computed tomography-derived fractional flow reserve and coronary computed tomography angiography at different levels of calcification. • Computed tomography-derived fractional flow reserve only has a better diagnostic performance than coronary computed tomography angiography with low amounts of coronary calcium. • For the low coronary artery calcium score group, computed tomography-derived fractional flow reserve might be a good non-invasive method to detect hemodynamic stenoses in coronary artery disease patients.

Effect of guidewire on the accuracy of trans-stenotic pressure measurement—A computational study

Accurate measurement of trans-stenotic pressure drop is vital for risk stratification in coronary artery disease. Currently, in vivo pressure measurement relies mostly on a pressure guidewire inserted into the artery, which inevitably alters local hemodynamics. To precisely assess the impact of guidewire insertion on the accuracy of pressure measurement, this study conducts numerical simulations with both an idealized straight-tube model and a patient-specific model. Results with and without a guidewire model are compared and analyzed. Results from the idealized model reveal that the insertion of a guidewire shifts velocity distribution, increases resistance, and amplifies the pressure drop across the stenosis. The patient-specific model also demonstrates that the guidewire causes non-negligible flow redistribution among the arterial branches, but the influence on pressure drop remains mostly localized. An analytical model for trans-stenotic pressure drop that takes the guidewire into consideration is also proposed and validated against the 3D simulation results. It is observed that the maximum relative error is around 3.0% in the patient-specific model, indicating the effectiveness of the analytical model in physiologically accurate settings. The proposed model can be used to align computed tomography-derived fractional flow reserve values with clinically recognized FFR standards established through guidewire measurements.

Diagnostic performance of noninvasive computed tomography-derived fractional flow reserve in patients with severe aortic stenosis

Abstract Background Noninvasive fractional flow reserve derived from coronary computed tomography angiography (FFRct) is developed as a decision-making tool in daily clinical practice. However, its diagnostic performance has not been sufficiently explored in patients with severe aortic stenosis (AS). Purpose To identify the diagnostic performance of FFRct in patients with severe AS using invasive fractional flow reserve (FFR) as the reference standard. Methods This study was a retrospective observational that included consecutive patients with severe AS undergoing TAVI who had concomitant intermediate coronary artery stenosis based on preoperative invasive coronary angiography. Preoperative invasive FFR and CT data preoperatively before TAVI were prospectively collected. Results We analyzed the data of patients with severe AS demonstrating intermediate coronary artery stenosis and compared the FFRct values with the invasive FFR values. Among 93 patients (100 vessels), the median FFR and FFRct (Q1, Q3) were 0.85 (0.78, 0.90) and 0.83 (0.72, 0.88), respectively. The FFRct values significantly correlated with the FFR values (r = 0.57; p &amp;lt; 0.0001). The vessel-based analysis of the accuracy of FFRct showed a sensitivity of 90.3%, specificity of 73.9%, positive predictive value of 60.9%, and negative predictive value of 94.4%. Conclusions FFRct demonstrated a significant correlation with invasive FFR and a high negative predictive value in patients with severe AS. These findings suggest that FFRct would be a clinically beneficial noninvasive tool for excluding functional coronary artery stenosis in patients with severe AS.

Diagnostic accuracy of a novel optical coherence tomography-based fractional flow reserve algorithm for assessment of coronary stenosis significance.

This study aimed to introduce a novel optical coherence tomography-derived fractional flow reserve (FFR) computational approach and assess the diagnostic performance of the algorithm for assessing physiological function. The fusion of coronary optical coherence tomography and angiography was used to generate a novel FFR algorithm (AccuFFRoct) to evaluate functional ischemia of coronary stenosis. In the current study, a total of 34 consecutive patients were included, and AccuFFRoct was used to calculate the FFR for these patients. With the wire-measured FFR as the reference standard, we evaluated the performance of our approach by accuracy, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). Per vessel accuracy, sensitivity, specificity, PPV, and NPV for AccuFFRoct in identifying hemodynamically significant coronary stenosis were 93.8%, 94.7%, 92.3%, 94.7%, and 92.3%, respectively, were found. Good correlation (Pearson's correlation coefficient r = 0.80, p < 0.001) between AccuFFRoct and FFR was observed. The Bland-Altman analysis showed a mean difference value of -0.037 (limits of agreement: -0.189 to 0.115). The area under the receiver-operating characteristic curve (AUC) of AccuFFRoct in identifying physiologically significant stenosis was 0.94, which was higher than the minimum lumen area (MLA, AUC = 0.91) and significantly higher than the diameter stenosis (%DS, AUC = 0.78). This clinical study shows the efficiency and accuracy of AccuFFRoct for clinical implementation when using invasive FFR measurement as a reference. It could provide important insights into coronary imaging superior to current methods based on the degree of coronary artery stenosis.

Clinical impacts of CT-derived fractional flow reserve under insurance reimbursement: Results from multicenter, prospective registry

BackgroundAlthough computed tomography-derived fractional flow reserve (FFRCT) has been reimbursed in a few countries, its impacts on daily practice of coronary artery diseases are not fully elucidated. We evaluated the clinical impacts of FFRCT under the real Japanese insurance reimbursement. MethodsIn the multicenter prospective registry: DYNAMIC-FFRCT study, a total of 410 patients who underwent FFRCT analysis under reimbursement were prospectively enrolled at 6 Japanese sites from October 2019 to November 2021. Coronary CT angiography and FFRCT findings, treatment plans, and 90-day outcomes were recorded. The primary endpoint was the redirection rate from the tests that might be expected without FFRCT [invasive coronary angiography (ICA)-selected group, myocardial perfusion single photon emission CT (MPS)-selected group, optimal medical therapy (OMT)-selected group, and others-selected group] to those that were actually performed based on FFRCT. ResultsICA could be avoided in 39.5 % in the ICA-selected group (N = 233). In particular, in 94.3 % of patients with an FFRCT value of >0.80, additional examinations, such as ICA, were avoided. In addition, in the MPS-selected group (N = 133), 92.6 % had no additional tests with FFRCT > 0.80, while only 2 cases with FFRCT ≤ 0.80 underwent additional MPS examination. On the contrary, 33.3 % of the OMT-selected group (N = 33) had FFRCT ≤ 0.80. Approximately, 35 % medical cost reduction was also finally expected. ConclusionIntroduction of FFRCT could not only reduce unnecessary ICA and be a test that replaces the conventional non-invasive functional assessment modality but also result in medical cost reduction even when used under real Japanese insurance reimbursement.

Clinical Outcomes Based on Coronary Computed Tomography-Derived Fractional Flow Reserve and Plaque Characterization

BackgroundCoronary computed tomography angiography (CTA) followed by computed tomography angiography–derived fractional flow reserve (FFRCT) is now commonly used for the management of chronic coronary syndrome (CCS). CTA-verified high-risk plaque (HRP) characteristics have also been reported to be associated with a greater likelihood of adverse cardiac events but have not been used for management decisions. ObjectivesThe aim of this study was to evaluate clinical outcomes based on a combination of point-of-care computed tomography angiography–derived fractional flow reserve (POC-FFRCT) and the presence of HRP in CCS patients initially treated medically or with revascularization based on invasive coronary angiography findings. MethodsCTA was performed as the initial test in 5,483 patients presenting with CCS between September 2015 and December 2020 followed by invasive coronary angiography and revascularization as necessary. POC-FFRCT assessment and HRP characterization were obtained subsequently in 745 consecutive patients. We investigated how HRP and POC-FFRCT, which were not available during the original clinical decision making, correlated with the endpoint defined as a composite of cardiac death, acute coronary syndrome, and a need for unplanned revascularization. ResultsCardiac events occurred in 20 patients (2.7%) during a median follow-up of 744 days. The event rate was significantly higher in patients with POC-FFRCT <0.80 compared with POC-FFRCT ≥0.8 (5.4 vs 0.5 per 100 vessel years; log-rank P < 0.0001) and in patients with HRP compared to those without HRP (3.6 vs 0.8 per 100 vessel years; log-rank P = 0.0001). POC-FFRCT <0.80 and the presence of HRP were the independent predictors of cardiac events (HR: 16.67; 95% CI: 2.63-105.39; P = 0.002) compared with POC-FFRCT ≥0.8 and absent HRP. For the vessels with POC-FFRCT <0.80 and HRP, a significantly higher rate of adverse events was observed in patients who did not undergo revascularization compared with those revascularized (16.4 vs 1.4 per 100 vessel years; log-rank P = 0.006). ConclusionsPOC-FFRCT <0.80 and the presence of HRP were the independent predictors of cardiac events, and revascularization of HRP lesions with abnormal POC-FFRCT was associated with a lower event rate.

Precisión diagnóstica de la TC-RFF con un nuevo algoritmo de subpíxel grueso a fino en la detección de isquemia específica de lesión: un estudio multicéntrico prospectivo

Introduction and objectivesA new computed tomography-derived fractional flow reserve (CT-FFR) technique with a “coarse-to-fine subpixel” algorithm has been developed to generate precise lumen contours. The aim of this study was to assess the diagnostic performance of this new CT-FFR algorithm for discriminating lesion-specific ischemia using wire-based FFR ≤ 0.80 as the reference standard in patients with coronary artery disease. MethodsThis prospective, multicenter study screened 330 patients undergoing coronary CT angiography (CCTA) and invasive FFR (median interval 2 days) from 6 tertiary hospitals. CT-FFR was evaluated in a blinded fashion with a “coarse-to-fine subpixel” algorithm for lumen contour. ResultsBetween March 2019 and May 2020, we included 316 patients with 324 vessels. There was a good correlation between CT-FFR and invasive FFR (r=0.76, P<.001). The diagnostic sensitivity, specificity, and accuracy on a per-vessel level were 95.3%, 89.8%, and 92.0% for CT-FFR, and 96.4%, 26.4%, and 53.1% for CCTA>50% stenosis, respectively. CT-FFR showed improved discrimination of ischemia compared with CCTA alone overall (AUC, 0.95 vs 0.74, P<.001) and in intermediate (AUC, 0.96 vs 0.62, P<.001) and “gray zone” lesions (AUC, 0.88 vs 0.61, P<.001). The diagnostic specificity, accuracy, and AUC for CT-FFR (71.9%, 82.8%, and 0.84) outperformed CCTA (9.4%, 48.3%, and 0.66) in patients or in vessels with severe calcification (all P<.05). ConclusionsCT-FFR with a new “coarse-to-fine subpixel” algorithm showed high performance in identifying hemodynamically significant stenosis. The diagnostic performance of CT-FFR was superior to that of CCTA in intermediate lesions, “gray zone” lesions, and severely calcified lesions.Clinical Trial Register: NCT04731285Full English text available from:www.revespcardiol.org/en

Science mapping analysis of computed tomography-derived fractional flow reverse: a bibliometric review from 2012 to 2022.

Computed tomography-derived fractional flow reserve (CT-FFR) is a non-invasive imagological examination used for diagnosing suspected coronary atherosclerotic heart disease, providing the morphological and functional value on a three-dimensional (3D) coronary artery model. This article aimed to collate the existing knowledge and predict this novel technology's future research hotspots. To collect data, 1,712 articles were retrieved from the Web of Science Core Collection (WoSCC) database from 2012-2022. CiteSpace5.8.R3 was used to visually analyze the research status and predict future research hotspots. Firstly, the United States, China, and the Netherlands were identified as the countries having published the most articles about CT-FFR. Jonathan Leipsic's group ranked first for the highest number of published articles. Secondly, the visualized analysis indicated that the exploration of CT-FFR is multi-disciplinary and involves cardiology, radiology, engineering, and computer science. Thirdly, the hotspots in this field, which were inferred from the keyword distribution and clustering, included the following: "diagnostic performance", "accuracy", and the "prognostic value" of CT-FFR, and comparison of CT-FFR and other imaging methods sharing similarities. The research frontiers included technologies utilized to obtain more accurate CT-FFR values, such as artificial intelligence (AI) and deep learning. As the first visualized bibliometric analysis on CT-FFR, this study captured the current accumulated information in this field and offer more insight and guidance for future research.

Sex-specific associations of cardiovascular risk factors and coronary plaque composition for hemodynamically significant coronary artery stenosis: a coronary computed tomography angiography study

BackgroundIt has been reported that there are sex differences in plaque composition and hemodynamically significant stenosis. This study aimed to explore the impact of sex on cardiovascular risk factors for specific plaque compositions and hemodynamically significant stenosis.MethodsData regarding demographics and cardiovascular risk factors were collected. Hemodynamically significant stenosis was identified by a computed tomography-derived fractional flow reserve of ≤ 0.8. Associations among cardiovascular risk factors, plaque composition, and hemodynamically significant stenosis were assessed using a multivariate binary logistic regression analysis across sexes. The discriminating capacity of diverse plaque components for hemodynamically significant stenosis was assessed by area under the receiver-operating characteristics curve with 95% confidence intervals.ResultsA total of 1164 patients (489 men and 675 women) were included. For men, hyperlipidemia and cigarette smoking were risk factors for each plaque component (all P < 0.05), and diabetes mellitus also predicted fibrotic components (P < 0.05). For women, risk factors for each plaque component were hypertension and diabetes mellitus (all P < 0.01). Nonetheless, hyperlipidemia (P < 0.05) was a specific risk factor for non-calcified components. Calcified components combined with fibrotic components showed superior discrimination of hemodynamically significant stenosis in men and calcified components alone in women (all P < 0.01). Hypertension (P < 0.01) was a risk factor for hemodynamically significant stenosis in women. In contrast, diabetes, hyperlipidemia, and cigarette smoking were risk factors for hemodynamically significant stenosis in men (all P < 0.05).ConclusionsIn men, hemodynamically significant stenosis was predicted by a combination of calcified and fibrotic components with multiple risk factors. In women, hemodynamically significant stenosis was predicted by calcified components caused by a single risk factor. It might be a key point to improve prognosis by more precise risk management between men and women, which needs to be proved by further prospective trials.

Deferred Testing in Stable Outpatients With Suspected Coronary Artery Disease

Guidelines recommend deferral of testing for symptomatic people with suspected coronary artery disease (CAD) and low pretest probability. To our knowledge, no randomized trial has prospectively evaluated such a strategy. To assess process of care and health outcomes in people identified as minimal risk for CAD when testing is deferred. This randomized, pragmatic effectiveness trial included prespecified subgroup analysis of the PRECISE trial at 65 North American and European sites. Participants identified as minimal risk by the validated PROMISE minimal risk score (PMRS) were included. Randomization to a precision strategy using the PMRS to assign those with minimal risk to deferred testing and others to coronary computed tomography angiography with selective computed tomography-derived fractional flow reserve, or to usual testing (stress testing or catheterization with PMRS masked). Randomization was stratified by PMRS risk. Composite of all-cause death, nonfatal myocardial infarction (MI), or catheterization without obstructive CAD through 12 months. Among 2103 participants, 422 were identified as minimal risk (20%) and randomized to deferred testing (n = 214) or usual testing (n = 208). Mean age (SD) was 46 (8.6) years; 304 were women (72%). During follow-up, 138 of those randomized to deferred testing never had testing (64%), whereas 76 had a downstream test (36%) (at median [IQR] 48 [15-78] days) for worsening (30%), uncontrolled (10%), or new symptoms (6%), or changing clinician preference (19%) or participant preference (10%). Results were normal for 96% of these tests. The primary end point occurred in 2 deferred testing (0.9%) and 13 usual testing participants (6.3%) (hazard ratio, 0.15; 95% CI, 0.03-0.66; P = .01). No death or MI was observed in the deferred testing participants, while 1 noncardiovascular death and 1 MI occurred in the usual testing group. Two participants (0.9%) had catheterizations without obstructive CAD in the deferred testing group and 12 (5.8%) with usual testing (P = .02). At baseline, 70% of participants had frequent angina and there was similar reduction of frequent angina to less than 20% at 12 months in both groups. In symptomatic participants with suspected CAD, identification of minimal risk by the PMRS guided a strategy of initially deferred testing. The strategy was safe with no observed adverse outcome events, fewer catheterizations without obstructive CAD, and similar symptom relief compared with usual testing. ClinicalTrials.gov Identifier: NCT03702244.

Diagnostic performance of a novel automated CT-derived FFR technology in detecting hemodynamically significant coronary artery stenoses: A multicenter trial in China

Computed tomography-derived fractional flow reserve (CT-derived FFR) algorithms have emerged as promising noninvasive methods for identifying hemodynamically significant coronary artery disease (CAD). However, its broad adaption is limited by the complex workflow, slow processing, and supercomputer requirement. Therefore, CT-derived FFR solutions capable of producing fast and accurate results could help deliver time-sensitive results rapidly and potentially alter patient management. The current study aimed to determine the diagnostic performance of a novel CT-derived FFR algorithm, esFFR, on patients with CAD was evaluated. 329 patients from 6 medical centers in China were included in this prospective study. CT-derived FFR calculations were performed on 350 vessels using the esFFR algorithm using patients' presenting coronary computed tomography angiography (CCTA) images, and results and processing speed were recorded. Using invasive FFR measurements from direct coronary angiography as the reference standard, the diagnostic performance of esFFR and CCTA in detecting hemodynamically significant lesions were compared. Post-hoc analyses were performed for patients with calcified lesions or stenoses within the CT-derived FFR diagnostic "gray zone." The esFFR values correlated well with invasive FFR. The sensitivity, specificity, accuracy, positive and negative predictive value for esFFR were all above 90%. The overall performance of esFFR was superior to CCTA. Coronary calcification had minimal effects on esFFR's diagnostic performance. It also maintained 85% of diagnostic accuracy for "gray zone" lesions, which historically was <50%. The average esFFR processing speed was 4.6 ± 1.3 minutes. The current study demonstrated esFFR had high diagnostic efficacy and fast processing speed in identifying hemodynamically significant CAD.

Global trans-lesional computed tomography-derived fractional flow reserve gradient is associated with clinical outcomes in diabetic patients with non-obstructive coronary artery disease

BackgroundCoronary computed tomography angiography (CCTA)-derived fractional flow reserve (CT-FFR) enables physiological assessment and risk stratification, which is of significance in diabetic patients with nonobstructive coronary artery disease (CAD). We aim to evaluate prognostic value of the global trans-lesional CT-FFR gradient (GΔCT-FFR), a novel metric, in patients with diabetes without flow-limiting stenosis.MethodsPatients with diabetes suspected of having CAD were prospectively enrolled. GΔCT-FFR was calculated as the sum of trans-lesional CT-FFR gradient in all epicardial vessels greater than 2 mm. Patients were stratified into low-gradient without flow-limiting group (CT-FFR > 0.75 and GΔCT-FFR < 0.20), high-gradient without flow-limiting group (CT-FFR > 0.75 and GΔCT-FFR ≥ 0.20), and flow-limiting group (CT-FFR ≤ 0.75). Discriminant ability for major adverse cardiovascular events (MACE) prediction was compared among 4 models [model 1: Framingham risk score; model 2: model 1 + Leiden score; model 3: model 2 + high-risk plaques (HRP); model 4: model 3 + GΔCT-FFR] to determine incremental prognostic value of GΔCT-FFR.ResultsOf 1215 patients (60.1 ± 10.3 years, 53.7% male), 11.3% suffered from MACE after a median follow-up of 57.3 months. GΔCT-FFR (HR: 2.88, 95% CI 1.76–4.70, P < 0.001) remained independent risk factors of MACE in multivariable analysis. Compared with the low-gradient without flow-limiting group, the high-gradient without flow-limiting group (HR: 2.86, 95% CI 1.75–4.68, P < 0.001) was associated with higher risk of MACE. Among the 4 risk models, model 4, which included GΔCT-FFR, showed the highest C-statistics (C-statistics: 0.75, P = 0.002) as well as a significant net reclassification improvement (NRI) beyond model 3 (NRI: 0.605, P < 0.001).ConclusionsIn diabetic patients with non-obstructive CAD, GΔCT-FFR was associated with clinical outcomes at 5 year follow-up, which illuminates a novel and feasible approach to improved risk stratification for a global hemodynamic assessment of coronary artery in diabetic patients.