Impact of coronary CT image quality on the accuracy of the FFRCT Planner.

OBJECTIVE: To assess the accuracy of a virtual stenting tool based on coronary CT angiography (CCTA) and fractional flow reserve (FFR) derived from CCTA (FFRCT Planner) across different levels of image quality. MATERIALS AND METHODS: Prospective, multicenter, single-arm study of patients with chronic coronary syndromes and lesions with FFR ≤ 0.80. All patients underwent CCTA performed with recent-generation scanners. CCTA image quality was adjudicated using the four-point Likert scale at a per-vessel level by an independent committee blinded to the FFRCT Planner. Patient- and technical-related factors that could affect the FFRCT Planner accuracy were evaluated. The FFRCT Planner was applied mirroring percutaneous coronary intervention (PCI) to determine the agreement with invasively measured post-PCI FFR. RESULTS: Overall, 120 patients (123 vessels) were included. Invasive post-PCI FFR was 0.88 ± 0.06 and Planner FFRCT was 0.86 ± 0.06 (mean difference 0.02 FFR units, the lower limit of agreement (LLA) - 0.12, upper limit of agreement (ULA) 0.15). CCTA image quality was assessed as excellent (Likert score 4) in 48.3%, good (Likert score 3) in 45%, and sufficient (Likert score 2) in 6.7% of patients. The FFRCT Planner was accurate across different levels of image quality with a mean difference between FFRCT Planner and invasive post-PCI FFR of 0.02 ± 0.07 in Likert score 4, 0.02 ± 0.07 in Likert score 3 and 0.03 ± 0.08 in Likert score 2, p = 0.695. Nitrate dose ≥ 0.8mg was the only independent factor associated with the accuracy of the FFRCT Planner (95%CI - 0.06 to - 0.001, p = 0.040). CONCLUSION: The FFRCT Planner was accurate in predicting post-PCI FFR independent of CCTA image quality. CLINICAL RELEVANCE STATEMENT: Being accurate in predicting post-PCI FFR across a wide spectrum of CT image quality, the FFRCT Planner could potentially enhance and guide the invasive treatment. Adequate vasodilation during CT acquisition is relevant to improve the accuracy of the FFRCT Planner. KEY POINTS: • The fractional flow reserve derived from coronary CT angiography (FFRCT) Planner is a novel tool able to accurately predict fractional flow reserve after percutaneous coronary intervention. • The accuracy of the FFRCT Planner was confirmed across a wide spectrum of CT image quality. Nitrates dose at CT acquisition was the only independent predictor of its accuracy. • The FFRCT Planner could potentially enhance and guide the invasive treatment.

Diagnostic Accuracy of Pre-Transcatheter Aortic Valve Replacement Nitroglycerin-Free Fractional Flow Reserve-Computed Tomography-Based Physiological Assessment in Patients With Severe Aortic Stenosis for Predicting Post-Transcatheter Aortic Valve Replacement Ischemia.

BACKGROUND: Fractional flow reserve-computed tomography (FFRCT) has not been validated in patients with severe aortic stenosis (AS) undergoing transcatheter aortic valve replacement (TAVR) for coronary artery disease due to theoretical difficulties in using nitroglycerin for such patients.Methods and Results: In this single-center study, we prospectively enrolled 21 patients (34 vessels) and performed pre-TAVR FFRCTwithout nitroglycerin, pre-TAVR invasive instantaneous wave-free ratio (iFR) measurements, and post-TAVR FFR measurements using a pressure wire. The diagnostic accuracy, sensitivity, specificity, positive predictive value, and negative predictive value of pre-TAVR FFRCT≤0.80 to predict post-TAVR invasive FFR ≤0.80 were 82%, 83%, 82%, 71%, and 90%, respectively. A receiver operating characteristic analysis demonstrated an optimal cutoff of 0.78 for pre-TAVR FFRCTto indicate post-TAVR FFR ≤0.80, with an area under the curve (AUC) of 0.84, and the counterpart cutoff of pre-TAVR iFR was 0.89 with an AUC of 0.86. CONCLUSIONS: FFRCTwithout nitroglycerin could be a useful non-invasive imaging modality for assessing the severity of coronary artery lesions in patients with severe AS.

Accuracy of subtraction fractional flow reserve with computed tomography in identifying early revascularization in patients with coronary artery disease.

OBJECTIVES: The diagnostic performance of fractional flow reserve with computed tomography (FFR-CT) is affected by the presence of calcified plaque. Subtraction can remove the influence of calcification in coronary computed tomography angiography (CCTA) to increase confidence in the diagnosis of coronary artery stenosis. Our purpose is to investigate the accuracy of post-subtraction FFR-CT in predicting early revascularization. DESIGN: Based on CCTA data of 237 vessels from 79 patients with coronary artery disease, subtraction CCTA images were obtained at a local post-processing workstation, and the conventional and post-subtraction FFR-CT measurements and the difference in proximal and distal FFR-CT values of the narrowest segment of the vessel (ΔFFR-CT) were analyzed for their accuracy in predicting early coronary artery hemodynamic reconstruction. RESULTS: With FFR-CT ≤ 0.8 as the criterion, the accuracy of conventional and post-subtraction FFR-CT measurements in predicting early revascularization was 73.4% and 77.2% at the patient level, and 64.6% and 72.2% at the vessel level, respectively. The specificity of post-subtraction FFR-CT measurements was significantly higher than that of conventional FFR-CT at both the patient and vessel levels (P of 0.013 and 0.015, respectively). At the vessel level, the area under the curve of receiver operating characteristic was 0.712 and 0.797 for conventional and post-subtraction ΔFFR-CT, respectively, showing a difference (P = 0.047), with optimal cutoff values of 0.07 and 0.11, respectively. CONCLUSION: The post-subtraction FFR-CT measurements enhance the specificity in predicting early revascularization. The post-subtraction ΔFFR-CT value of the stenosis segment > 0.11 may be an important indicator for early revascularization.

Utility of FFRCT in Patients with Chest Pain.

PURPOSE OF REVIEW: The goal of this article is to review the data supporting the use of fractional flow reserve derived from coronary computed tomography angiography (FFRCT) in patients with chest pain. REVIEW FINDINGS: Numerous clinical trials have demonstrated that the diagnostic accuracy of coronary computed tomography angiography (CCTA) can be improved with the use of FFRCT, primarily due to its superior specificity when compared to CCTA alone. This promising development may help reduce the need for invasive angiography in patients presenting with chest pain. Furthermore, some studies have indicated that incorporating FFRCT into decision-making is safe, with an FFRCT value of ≥ 0.8 being associated with favorable outcomes. While FFRCT has been shown to be feasible in patients with acute chest pain, further large-scale studies are warranted to confirm its utility. The emergence of FFRCT as a tool for the management of patients with chest pain is promising. However, potential limitations require the interpretation of FFRCT in conjunction with clinical context.

Impact of coronary bifurcation angle on computed tomography derived fractional flow reserve in coronary vessels with no apparent coronary artery disease.

OBJECTIVES: Computed tomography (CT) derived fractional flow reserve (FFRCT) decreases from the proximal to the distal part due to a variety of factors. The energy loss due to the bifurcation angle may potentially contribute to a progressive decline in FFRCT. However, the association of the bifurcation angle with FFRCT is still not entirely understood. This study aimed to investigate the impact of various bifurcation angles on FFRCT decline below the clinically crucial relevance of 0.80 in vessels with no apparent coronary artery disease (CAD). METHODS: A total of 83 patients who underwent both CT angiography including FFRCT and invasive coronary angiography, exhibiting no apparent CAD were evaluated. ΔFFRCT was defined as the change in FFRCT from the proximal to the distal in the left anterior descending artery (LAD) and left circumflex artery (LCX). The bifurcation angle was calculated from three-dimensional volume rendered images. Vessel morphology and plaque characteristics were also assessed. RESULTS: ΔFFRCT significantly correlated with the bifurcation angle (LAD angle, r = 0.35, p = 0.001; LCX angle, r = 0.26, p = 0.02) and vessel length (LAD angle, r = 0.30, p = 0.005; LCX angle, r = 0.49, p < 0.0001). In LAD, vessel length was the strongest predictor for distal FFRCT of ≤ 0.80 (ß-coefficient = 0.55, p = 0.0003), immediately followed by the bifurcation angle (ß-coefficient = 0.24, p = 0.02). The bifurcation angle was a good predictor for a distal FFRCT ≤ 0.80 (LAD angle, cut-off 31.0°, AUC 0.70, sensitivity 74%, specificity 68%; LCX angle, cut-off 52.6°, AUC 0.86, sensitivity 88%, specificity 85%). CONCLUSIONS: In vessels with no apparent CAD, vessel length was the most influential factor on FFRCT, directly followed by the bifurcation angle. KEY POINTS: • Both LAD and LCX bifurcation angles are factors influencing FFR CT. • Bifurcation angle is one of the predictors of a distal FFRCT of ≤ 0.80 and an optimal cut-off value of 31.0° for the LAD and 52.6° for the LCX. • Bifurcation angle should be taken into consideration when interpreting numerical values of FFRCT.

High-Speed On-Site Deep Learning-Based FFR-CT Algorithm: Evaluation Using Invasive Angiography as the Reference Standard.

BACKGROUND. Estimation of fractional flow reserve from coronary CTA (FFR-CT) is an established method of assessing the hemodynamic significance of coronary lesions. However, clinical implementation has progressed slowly, partly because of off-site data transfer with long turnaround times for results. OBJECTIVE. The purpose of this study was to evaluate the diagnostic performance of FFR-CT computed on-site with a high-speed deep learning-based algorithm with invasive hemodynamic indexes as the reference standard. METHODS. This retrospective study included 59 patients (46 men, 13 women; mean age, 66.5 ± 10.2 years) who underwent coronary CTA (including calcium scoring) followed within 90 days by invasive angiography with invasive fractional flow reserve (FFR) and/or instantaneous wave-free ratio measurements from December 2014 to October 2021. Coronary artery lesions were considered to have hemodynamically significant stenosis in the presence of invasive FFR of 0.80 or less and/or instantaneous wave-free ratio of 0.89 or less. A single cardiologist evaluated the CTA images using an on-site deep learning-based semiautomated algorithm entailing a 3D computational flow dynamics model to determine FFR-CT for coronary artery lesions detected with invasive angiography. Time for FFR-CT analysis was recorded. FFR-CT analysis was repeated by the same cardiologist in 26 randomly selected examinations and by a different cardiologist in 45 randomly selected examinations. Diagnostic performance and agreement were assessed. RESULTS. A total of 74 lesions were identified with invasive angiography. FFR-CT and invasive FFR had strong correlation (r = 0.81) and, in Bland-Altman analysis, bias of 0.01 and 95% limits of agreement of -0.13 to 0.15. FFR-CT had AUC for hemodynamically significant stenosis of 0.975. At a cutoff of 0.80 or less, FFR-CT had 95.9% accuracy, 93.5% sensitivity, and 97.7% specificity. In 39 lesions with severe calcifications (≥ 400 Agatston units), FFR-CT had AUC of 0.991 and at a cutoff of 0.80, 94.7% sensitivity, 95.0% specificity, and 94.9% accuracy. Mean analysis time per patient was 7 minutes 54 seconds. Intraobserver agreement (intraclass correlation coefficient, 0.85; bias, -0.01; 95% limits of agreement, -0.12 and 0.10) and interobserver agreement (intraclass correlation coefficient, 0.94; bias, -0.01; 95% limits of agreement, -0.08 and 0.07) were good to excellent. CONCLUSION. A high-speed on-site deep learning-based FFR-CT algorithm had excellent diagnostic performance for hemodynamically significant stenosis with high reproducibility. CLINICAL IMPACT. The algorithm should facilitate implementation of FFR-CT technology into routine clinical practice.

Impact of ramus coronary artery on computed tomography derived fractional flow reserve (FFRCT ) in no apparent coronary artery disease.

BACKGROUND: The ramus artery contributes to the development of turbulence, which may influence computed tomography (CT) derived fractional flow reserve (FFRCT ) even without coronary artery disease (CAD). The relationship between ramus-induced turbulence and FFRCT is unclear. METHOD AND RESULTS: A total of 120 patients with <20% coronary stenosis assessed by both FFRCT and invasive coronary angiography were evaluated. The patients were divided into three groups: absent-ramus (n = 72), small-ramus that could not be analyzed by FFRCT (n = 18), and large-ramus that could be analyzed by FFRCT (n = 30). FFRCT measurements were performed at the proximal and distal segments of the left anterior descending (LAD), left circumflex (LCX), and ramus artery. With absent-ramus and small-absent ramus groups, FFRCT was measured at the distal end of the left main trunk at the same level for the proximal segments of the LAD and LCX. In absent-ramus group, proximal FFRCT showed no significant differences between three vessels (LAD = .96 ± .02; MID = .97 ± .02; LCX = .97 ± .02). However, in small and large-ramus groups, proximal FFRCT was significantly higher in the ramus artery than LAD and LCX (small-ramus, LAD = .95 ± .03, Ramus = .97 ± .02, LCX = .95 ± .03; large-ramus: LAD = .95 ± .03, Ramus = .98 ± .01; LCX = .96 ± .03; p < .05). A large ramus was associated with a higher prevalence of a distal FFRCT ≤.80 (odds ratio 7.0, 95% CI 1.2-40.1, p = .03). A proximal ramus diameter predicted distal FFRCT ≤.80 (cut-off 2.1 mm, AUC .76, sensitivity 100%, specificity 52%, 95% CI .61-.90). CONCLUSIONS: The presence of a large-ramus artery may cause an FFRCT decline in no apparent CAD.

Recent Advances in Coronary Computed Tomography Angiogram: The Ultimate Tool for Coronary Artery Disease.

PURPOSE OF REVIEW: The emerging technologies in multidetector computed tomography scanners gave the ability to image coronary arteries in a single heartbeat, at a higher quality, and low radiation dose. Furthermore, incorporating artificial intelligence and machine learning into image processing and interpretation have extended the use for coronary computed tomography angiogram (CCTA) and its applications. In this review, we will explore the recent evidence and advances supporting CCTA to become the ultimate tool for coronary artery disease. RECENT FINDINGS: Results from the EVINCI, ISCHEMIA, SCOT-HEART, and PROMISE showed that CCTA is better in patients' risk stratification and in detecting subclinical atherosclerosis, resulting in earlier interventions and lesser events. Additionally, CCTA gave us a closer look on atherosclerotic disease by identifying different type of plaque and their clinical significance. Furthermore, FFRCT is a notable example of incorporating artificial intelligence into CCTA. This technology helped us to accurately and non-invasively identify flow limiting lesions, guiding revascularization. As a result of the recent evidence, CCTA have made its way into the chest pain guidelines all over the world. Moreover, CCTA have the potential to revolutionize our understanding and standards in screening, preventing, and managing heart disease.

Paradoxical changes of coronary computed tomography derived fractional flow reserve.

A total of 1335 outpatients with suspected coronary artery disease and who underwent computed tomography derived fractional flow reserve (FFRCT ) analysis were examined. Only four patients showed reverse increase of FFRCT from the proximal to the distal vessel and all of them had a large ramus artery (RAM). Of all parameters (vessel length, lumen volume, plaque volume, and left ventricular mass), only the bifurcation angle was significantly higher in reverse increase of FFRCT with RAM group (106.0 ± 15.8°) than normal FFRCT with RAM group (82.6 ± 21.7°) and normal FFRCT without RAM group (66.9 ± 21.1°).

Fractional flow reserve derived from computed tomography coronary angiography in the assessment and management of stable chest pain: the FORECAST randomized trial.

AIMS: Fractional flow reserve (FFRCT) using computed tomography coronary angiography (CTCA) determines both the presence of coronary artery disease and vessel-specific ischaemia. We tested whether an evaluation strategy based on FFRCT would improve economic and clinical outcomes compared with standard care. METHODS AND RESULTS: Overall, 1400 patients with stable chest pain in 11 centres were randomized to initial testing with CTCA with selective FFRCT (experimental group) or standard clinical care pathways (standard group). The primary endpoint was total cardiac costs at 9 months. Secondary endpoints were angina status, quality of life, major adverse cardiac and cerebrovascular events, and use of invasive coronary angiography. Randomized groups were similar at baseline. Most patients had an initial CTCA: 439 (63%) in the standard group vs. 674 (96%) in the experimental group, 254 of whom (38%) underwent FFRCT. Mean total cardiac costs were higher by £114 (+8%) in the experimental group, with a 95% confidence interval from -£112 (-8%) to +£337 (+23%), though the difference was not significant (P = 0.10). Major adverse cardiac and cerebrovascular events did not differ significantly (10.2% in the experimental group vs. 10.6% in the standard group) and angina and quality of life improved to a similar degree over follow-up in both randomized groups. Invasive angiography was reduced significantly in the experimental group (19% vs. 25%, P = 0.01). CONCLUSION: A strategy of CTCA with selective FFRCT in patients with stable angina did not differ significantly from standard clinical care pathways in cost or clinical outcomes, but did reduce the use of invasive coronary angiography.

The complementary nature of multimodal imaging in the management of an anomalous aortic origin of the right coronary artery from the left coronary cusp.

Anomalous aortic origins of coronary arteries (AAOCA) are congenital abnormalities involving the origin and course of coronary arteries and present with diverse clinical manifestations in patients ranging from asymptomatic incidental findings to sudden cardiac death. The current case describes a patient with an anomalous right coronary artery with an anterior interarterial course originating from a separate ostium at the left coronary cusp. By utilizing complementary multimodality imaging techniques including fractional flow reserve (FFRCT), we obtained a comprehensive functional and anatomic assessment resulting in appropriate surgical therapy and a good clinical outcome.

Prognostic value of cardiac CT.

In the past decades, coronary computed tomography angiography (CCTA) has become a powerful tool in the management of coronary artery disease. The diagnostic and prognostic value of CCTA has been extensively demonstrated in both large observational studies and clinical trials among stable chest pain patients. The quantification of coronary artery calcium score (CACS) is a well-established predictor of cardiovascular morbidity and mortality in asymptomatic subjects. Besides CACS, the main strength of CCTA is the accurate assessment of the individual total atherosclerotic plaque burden, which holds important prognostic information. In addition, CCTA, by providing detailed information on coronary plaque morphology and composition with identification of specific high-risk plaque features, may further improve the risk stratification beyond the assessment of coronary stenosis. The development of new CCTA applications, such as stress myocardial CT perfusion and computational fluids dynamic applied to standard CCTA to derive CT-based fractional flow reserve (FFR) values have shown promising results to guide revascularization, potentially improving clinical outcomes in stable chest pain patients. In this review, starting from the role of CACS and moving beyond coronary stenosis, we evaluate the existing evidence of the prognostic effectiveness of the CCTA strategy in real-world clinical practice.

CT-Derived Fractional Flow Reserve (FFRCT): From Gatekeeping to Roadmapping.

Coronary computed tomography angiography (CCTA) has emerged as the preferred modality in the diagnosis of coronary artery disease, but it is limited by modest specificity. By applying principles of computational fluid dynamics, flow fraction reserve, a measure of lesion-specific ischemia that is used to guide revascularization, can be noninvasively derived from CCTA, the so-called computed tomography-derived flow fractional reserve (FFRCT). The accuracy of FFRCT in discriminating ischemia has been extensively validated, and it has been shown to improve the specificity of CCTA. Compared to other stress myocardial perfusion imaging, FFRCT has superior or comparable accuracy. Clinical studies have provided strong evidence that FFRCT has significant prognostic implications and informs clinical decisions for revascularization, serving as a gatekeeper to invasive coronary angiography. In addition, FFRCT-based tools can be used to simulate the physiological consequences of different revascularization strategies, thus providing the roadmap to achieve complete revascularization. Although challenges remain, ongoing research and randomized controlled trials are expected to address current limitations and better define its role in clinical practice.

Evaluation of acute chest pain: Evolving paradigm of coronary risk scores and imaging.

There is a broad differential diagnosis for patients presenting with acute chest pain. History, physical examination, electrocardiogram, and serial troponin assays are pivotal in assessing patients with suspected acute coronary syndrome. However, if the initial workup is equivocal, physicians are faced with a challenge to find the optimal strategy for further triage. Risk stratification scores have been validated for patients with known acute coronary syndrome, such as the TIMI and GRACE scores, but there may be limitations in undifferentiated chest pain patients. Advancements in imaging modalities such as coronary computed tomography angiography and the addition CT derived fractional flow reserve, have demonstrated utility in evaluating patients presenting with acute chest pain. With this article, we aim to provide a comprehensive review of the non-invasive modalities that are available to evaluate acute chest pain patients suspected of cardiac etiology in the emergency room. We also added a focus on new imaging modalities that have shown to have prognostic implications in stable ischemic heart disease.

Clinical Impact of Coronary Computed Tomography Angiography-Derived Fractional Flow Reserve on Japanese Population in the ADVANCE Registry.

BACKGROUND: Coronary computed tomography angiography (cCTA)-derived fractional flow reserve (FFRCT) is a promising diagnostic method for the evaluation of coronary artery disease (CAD). However, clinical data regarding FFRCTin Japan are scarce, so we assessed the clinical impact of using FFRCTin a Japanese population.Methods and Results:The ADVANCE registry is an international prospective FFRCTregistry of patients suspected of CAD. Of 5,083 patients, 1,829 subjects enrolled from Japan were analyzed. Demographics, symptoms, cCTA, FFRCT, treatment strategy, and 90-day major cardiovascular events (MACE) were assessed. Reclassification of treatment strategy between cCTA alone and cCTA+FFRCToccurred in 55.8% of site investigations and in 56.9% in the core laboratory analysis. Patients with positive FFR (FFRCT≤0.80) were less likely to have non-obstructive disease on invasive coronary angiography than patients with negative FFR (FFRCT>0.80) (20.5% vs. 46.1%, P=0.0001). After FFRCT, 67.0% of patients with positive results underwent revascularization, whereas 96.1% of patients with negative FFRCTwere medically treated. MACE occurred in 5 patients with positive FFRCT, but none occurred in patients with negative FFRCTwithin 90 days. CONCLUSIONS: In this Japanese population, FFRCTmodified the treatment strategy in more than half of the patients. FFRCTshowed potential for stratifying patients suspected of CAD properly into invasive or non-invasive management pathways.

Coronary computed tomographic angiography-derived anatomic and hemodynamic plaque characteristics in prediction of cardiovascular events.

This study investigated the association of anatomic and hemodynamic plaque characteristics based on deep learning coronary computed tomography angiography (CCTA) with high-risk plaques that caused subsequent major adverse cardiovascular events (MACE). A retrospective analysis was conducted on patients who underwent CCTA between 1 month and 3 years prior to the occurrence of a MACE. Deep learning and computational fluid dynamics algorithms based on CCTA were applied to extract adverse plaque characteristics (low-attenuation plaque, positive remodeling, napkin-ring sign, and spotty calcification), and hemodynamic parameters (fractional flow reserve derived by coronary computed tomographic angiography [FFRCT], change in FFRCT across the lesion [△FFRCT], wall shear stress [WSS], and axial plaque stress [APS]). Correlation analysis, logistic regression, and Cox proportional risk analysis were conducted to understand the relationship between these measures and the occurrence of MACE and assess the value of hemodynamic parameters in predicting the incidence of MACE events and their prognosis. Our study included 86 patients with a total of 134 vessels exhibiting plaque formation and 83 culprit vessels with a subsequent coronary event. Culprit vessels had percent diameter stenosis [%DS] (0.54 ± 0.16 vs. 0.62 ± 0.13, P = 0.003), larger non-calcified plaque volume (45.8 vs. 101.7, P < 0.001), larger low-attenuation plaque volume (3.6 vs. 14.5, P < 0.001), more lesions with ≥ 3 adverse plaque characteristics (APC) (4 vs.26, P = 0.002), and worse hemodynamic features of adverse plaque. FFRCT demonstrated better visualization of maximum achievable flow in the presence of coronary stenosis and better correlation with the stenosis severity, while maximum of wall shear stress (WSSmax) was highly correlated with low-attenuation plaques and APC. The inclusion of hemodynamic parameters improved the efficacy of the predictive model, and a high WSS suggested a higher probability of MACE. Hemodynamic parameters based on CCTA are significantly correlated with plaque morphology. Importantly, integrating CCTA-derived parameters can refine the predictive performance of MACE occurrence.

Distal-vessel fractional flow reserve by computed tomography to monitor epicardial coronary artery disease.

AIMS: Coronary computed tomography angiography (CTA) and fractional flow reserve by computed tomography (FFR-CT) are increasingly utilized to characterize coronary artery disease (CAD). We evaluated the feasibility of distal-vessel FFR-CT as an integrated measure of epicardial CAD that can be followed serially, assessed the CTA parameters that correlate with distal-vessel FFR-CT, and determined the combination of clinical and CTA parameters that best predict distal-vessel FFR-CT and distal-vessel FFR-CT changes. METHODS AND RESULTS: Patients (n = 71) who underwent serial CTA scans at ≥2 years interval (median = 5.2 years) over a 14-year period were included in this retrospective study. Coronary arteries were analysed blindly using artificial intelligence-enabled quantitative coronary CTA. Two investigators jointly determined the anatomic location and corresponding distal-vessel FFR-CT values at CT1 and CT2. A total of 45.3% had no significant change, 27.8% an improvement, and 26.9% a worsening in distal-vessel FFR-CT at CT2. Stepwise multiple logistic regression analysis identified a four-parameter model consisting of stenosis diameter ratio, lumen volume, low density plaque volume, and age, that best predicted distal-vessel FFR-CT ≤ 0.80 with an area under the curve (AUC) = 0.820 at CT1 and AUC = 0.799 at CT2. Improvement of distal-vessel FFR-CT was captured by a decrease in high-risk plaque and increases in lumen volume and remodelling index (AUC = 0.865), whereas increases in stenosis diameter ratio, medium density calcified plaque volume, and total cholesterol presaged worsening of distal-vessel FFR-CT (AUC = 0.707). CONCLUSION: Distal-vessel FFR-CT permits the integrative assessment of epicardial atherosclerotic plaque burden in a vessel-specific manner and can be followed serially to determine changes in global CAD.

CT-derived Fractional Flow Reserve: How, When, and Where to use this Novel Cardiac Imaging Tool.

Fractional flow reserve computed tomography (FFRCT) is a novel imaging modality. It utilizes computational fluid dynamics analysis of coronary blood flow obtained from CCTA images to estimate the decrease in pressure across coronary stenosis during the maximum hyperemia. The FFRCT can serve as a valuable tool in the assessment of coronary artery disease (CAD). This non-invasive option can be used as an alternative to the invasive fractional Flow Reserve (FFR) evaluation, which is presently considered the gold standard for evaluating the physiological significance of coronary stenoses. It can help in several clinical situations, including Assessment of Acute and stable chest pain, virtual planning for coronary stenting, and treatment decision-making. Although FFRCT has demonstrated potential clinical applications as a non-invasive imaging technique, it is also crucial to acknowledge its limitations in clinical practice. As a result, it is imperative to meticulously evaluate the advantages and drawbacks of FFRCT individually and contemplate its application in combination with other diagnostic examinations and clinical data.

Completeness of revascularization by FFRCT in stable angina: Association to adverse cardiovascular outcomes.

BACKGROUND: The prognostic impact of complete coronary revascularization relative to non-invasive testing methods is unknown. OBJECTIVES: To assess the association between completeness of revascularization defined by CTA-derived fractional flow reserve (FFRCT) and cardiovascular outcomes in patients with stable angina. METHODS: Multicenter 3-year follow-up study of patients with new onset stable angina and ≥ 30% stenosis by CTA. The lesion-specific FFRCT value (two cm-distal-to-stenosis) was registered in all vessels with stenosis and considered abnormal when ≤ 0.80. Patients with FFRCT ≤ 0.80 were categorized as: Completely revascularized (CR-FFRCT), all vessels with FFRCT ≤ 0.80 revascularized; incompletely revascularized (IR-FFRCT), ≥ 1 vessels with FFRCT ≤ 0.80 non-revascularized. Early revascularization (< 90 days from index CTA) categorized vessels as revascularized. The primary endpoint comprised cardiovascular death and non-fatal myocardial infarction; the secondary endpoint vessel-specific late revascularization and non-fatal myocardial infarction. RESULTS: Amongst 900 patients and 1759 vessels, FFRCT was ≤ 0.80 in 377 (42%) patients, 536 (30%) vessels; revascularization was performed in 244 (27%) patients, 340 (19%) vessels. Risk of the primary endpoint was higher for IR-FFRCT (15/210 [7.1%]) compared to CR-FFRCT (4/167 [2.4%]), RR: 2.98; 95% CI: 1.01-8.8, p â€‹= â€‹0.036, and to normal FFRCT (3/523 [0.6%]), RR: 12.45; 95% CI: 3.6-42.6, p â€‹< â€‹0.001. Incidence of the secondary endpoint was higher in non-revascularized vessels with FFRCT ≤ 0.80 (29/250 [12%]) compared to revascularized vessels with FFRCT ≤ 0.80 (5/286 [1.7%]), p â€‹= â€‹0.001, and to vessels with FFRCT > 0.80 (10/1223 [0.8%]), p â€‹< â€‹0.001. CONCLUSION: Incomplete revascularization of patients with lesion-specific FFRCT ≤ 0.80 is associated to unfavorable cardiovascular outcomes compared to those with complete revascularization or FFRCT > 0.80.

Coronary computed tomography angiography derived fractional flow reserve and risk of recurrent angina: A 3-year follow-up study.

BACKGROUND: The association between coronary computed tomography angiography (CTA) derived fractional flow reserve (FFRCT) and risk of recurrent angina in patients with new onset stable angina pectoris (SAP) and stenosis by CTA is uncertain. METHODS: Multicenter 3-year follow-up study of patients presenting with symptoms suggestive of new onset SAP who underwent first-line CTA evaluation and subsequent standard-of-care treatment. All patients had at least one ≥30 â€‹% coronary stenosis. A per-patient lowest FFRCT-value ≤0.80 represented an abnormal test result. Patients with FFRCT ≤0.80 who underwent revascularization were categorized according to completeness of revascularization: 1) Completely revascularized (CR-FFRCT), all vessels with FFRCT ≤0.80 revascularized; or 2) incompletely revascularized (IR-FFRCT) ≥1 vessels with FFRCT ≤0.80 non-revascularized. Recurrent angina was evaluated using the Seattle Angina Questionnaire. RESULTS: Amongst 769 patients (619 [80 â€‹%] stenosis ≥50 â€‹%, 510 [66 â€‹%] FFRCT ≤0.80), 174 (23 â€‹%) reported recurrent angina at follow-up. An FFRCT ≤0.80 vs â€‹> â€‹0.80 associated to increased risk of recurrent angina, relative risk (RR): 1.82; 95 â€‹% CI: 1.31-2.52, p â€‹< â€‹0.001. Risk of recurrent angina in CR-FFRCT (n â€‹= â€‹135) was similar to patients with FFRCT >0.80, 13 â€‹% vs 15 â€‹%, RR: 0.93; 95 â€‹% CI: 0.62-1.40, p â€‹= â€‹0.72, while IR-FFRCT (n â€‹= â€‹90) and non-revascularized patients with FFRCT ≤0.80 (n â€‹= â€‹285) had increased risk, 37 â€‹% vs 15 â€‹% RR: 2.50; 95 â€‹% CI: 1.68-3.73, p â€‹< â€‹0.001 and 30 â€‹% vs 15 â€‹%, RR: 2.03; 95 â€‹% CI: 1.44-2.87, p â€‹< â€‹0.001, respectively. Use of antianginal medication was similar across study groups. CONCLUSION: In patients with SAP and coronary stenosis by CTA undergoing standard-of-care guided treatment, FFRCT provides information regarding risk of recurrent angina.