Computed Tomography Fractional Flow Reserve Research Articles

Novel motion correction algorithm improves diagnostic performance of CT fractional flow reserve

ObjectivesThis study aimed to investigate the diagnostic performance of computed tomography (CT) fractional flow reserve (CT-FFR) derived from standard images (STD) and images processed via first-generation (SnapShot Freeze, SSF1) and second-generation (SnapShot Freeze 2, SSF2) motion correction algorithms. Methods151 patients who underwent coronary CT angiography (CCTA) and invasive coronary angiography (ICA)/FFR within 3 months were retrospectively included. CCTA images were reconstructed using an iterative reconstruction technique and then further processed through SSF1 and SSF2 algorithms. All images were divided into three groups: STD, SSF1, and SSF2. Obstructive stenosis was defined as a diameter stenosis of ≥ 50 % in the left main artery or ≥ 70 % in other epicardial vessels. Stenosis with an FFR of ≤ 0.8 or a diameter stenosis of ≥ 90 % (as revealed via ICA) was considered ischemic. In patients with multiple lesions, the lesion with lowest CT-FFR was used for patient-level analysis. ResultsThe overall quality score in SSF2 group (median = 3.67) was markedly higher than that in STD (median = 3) and SSF1 (median = 3) groups (P < 0.001). The best correlation (r = 0.652, P < 0.001) and consistency (mean difference = 0.04) between the CT-FFR and FFR values were observed in the SSF2 group. At the per-lesion level, CT-FFRSSF2 outperformed CT-FFRSSF1 in diagnosing ischemic lesions (area under the curve = 0.887 vs. 0.795, P < 0.001). At the per-patient level, the SSF2 group also demonstrated the highest diagnostic performance. ConclusionThe SSF2 algorithm significantly improved CCTA image quality and enhanced its diagnostic performance for evaluating stenosis severity and CT-FFR calculations.

ESR Essentials: imaging in stable chest pain - practice recommendations by ESCR.

Stable chest pain is a common symptom with multiple potential causes. Non-invasive imaging has an important role in diagnosis and guiding management through the assessment of coronary stenoses, atherosclerotic plaque, myocardial ischaemia or infarction, and cardiac function. Computed tomography (CT) provides the anatomical evaluation of coronary artery disease (CAD) with the assessment of stenosis, plaque type and plaque burden, with additional functional information available from CT fractional flow reserve (FFR) or CT myocardial perfusion imaging. Stress magnetic resonance imaging, nuclear stress myocardial perfusion imaging, and stress echocardiography can assess myocardial ischaemia and other cardiac functional parameters. Coronary CT angiography can be used as a first-line test for many patients with stable chest pain, particularly those with low to intermediate pre-test probability. Functional testing may be considered for patients with known CAD, where the clinical significance is uncertain based on anatomical testing, or in patients with high pre-test probability. This practice recommendations document can be used to guide the selection of non-invasive imaging for patients with stable chest pain and provides brief recommendations on how to perform and report these diagnostic tests.

Factors Influencing Functional Coronary Artery Ischemia: A Gender-Specific Predictive Model.

The objective of this study was to explore factors that impact functional coronary artery ischemia (FCAI) and develop a gender-specific prognostic model that could serve as a benchmark for predicting FCAI in clinical practice. A cumulative total of 330 patients were enrolled comprising 634 main and branch coronary, consisting of 179 men (359 coronary arteries) and 151 women (275 coronary arteries). Based on the computed tomography-fractional flow reserve (CT-FFR), the coronary arteries of male and female patients were classified into the non-ischemic group (CT-FFR ≥ 0.80) and the ischemic group (CT-FFR < 0.80). We screened for factors related to the CT-FFR values of the coronary arteries in male and female patients and developed corresponding gender-specific models. In male patients, the correlation between FCAI and several indicators, including white blood cell (WBC) count, left anterior descending artery (LAD) lesions, pericoronary fat attenuation index (FAI), and the degree of coronary artery stenosis, was found to be statistically significant. A predictive model was developed using these factors, yielding an area under the curve (AUC) value of 0.812, with a P value of < 0.001 and a 95% confidence interval (CI) ranging from 0.767 to 0.857. This model demonstrated superior predictive capability compared to any individual indicators mentioned above. Significant correlations with FCAI were observed in female patients for hemoglobin (Hb), systolic blood pressure (SBP), FAI, and the degree of coronary artery stenosis. The predictive model, derived from these factors, exhibited robust performance with an area under the curve (AUC) value of 0.818, a P value of < 0.001, and a 95% confidence interval (CI) ranging from 0.764 to 0.872. Gender disparities exist in the factors affecting FCAI, underscoring the need for a gender-specific predictive model to enhance the precision of FCAI prediction.

Computed Tomography Fractional Flow Reserve Discrepancies With Invasive Angiography and Physiology

Computed Tomography Fractional Flow Reserve Discrepancies With Invasive Angiography and Physiology

Detecting lesion-specific ischemia in patients with coronary artery disease with computed tomography fractional flow reserve measured at different sites

ObjectivesWhether a stenosis can cause hemodynamic lesion-specific ischemia is critical for the treatment decision in patients with coronary artery disease (CAD). Based on coronary computed tomography angiography (CCTA), CT fractional flow reserve (FFRCT) can be used to assess lesion-specific ischemia. The selection of an appropriate site along the coronary artery tree is vital for measuring FFRCT. However the optimal site to measure FFRCT for a target stenosis remains to be adequately determined. The purpose of this study was to determine the optimal site to measure FFRCT for a target lesion in detecting lesion-specific ischemia in CAD patients by evaluating the performance of FFRCT measured at different sites distal to the target lesion in detecting lesion-specific ischemia with FFR measured with invasive coronary angiography (ICA) as reference standard.MethodsIn this single-center retrospective cohort study, a total of 401 patients suspected of having CAD underwent invasive ICA and FFR between March 2017 and December 2021 were identified. 52 patients having both CCTA and invasive FFR within 90 days were enrolled. Patients with vessels 30%-90% diameter stenosis as determined by ICA were referred to invasive FFR evaluation, which was performed 2–3 cm distal to the stenosis under the condition of hyperemia. For each vessel with 30%–90% diameter stenosis, if only one stenosis was present, this stenosis was selected as the target lesion; if serial stenoses were present, the stenosis most distal to the vessel end was chosen as the target lesion. FFRCT was measured at four sites: 1 cm, 2 cm, and 3 cm distal to the lower border of the target lesion (FFRCT-1 cm, FFRCT-2 cm, FFRCT-3 cm), and the lowest FFRCT at the distal vessel tip (FFRCT-lowest). The normality of quantitative data was assessed using the Shapiro–Wilk test. Pearson's correlation analysis and Bland–Altman plots were used for assessing the correlation and difference between invasive FFR and FFRCT. Correlation coefficients derived from Chi-suqare test were used to assess the correlation between invasive FFR and the cominbaiton of FFRCT measred at four sites. The performances of significant obstruction stenosis (diameter stenosis ≥ 50%) at CCTA and FFRCT measured at the four sites and their combinations in diagnosing lesion-specific ischemia were evaluated by receiver-operating characteristic (ROC) curves using invasive FFR as the reference standard. The areas under ROC curves (AUCs) of CCTA and FFRCT were compared by the DeLong test.ResultsA total of 72 coronary arteries in 52 patients were included for analysis. Twenty-five vessels (34.7%) had lesion-specific ischemia detected by invasive FFR and 47 vesseles (65.3%) had no lesion-spefifice ischemia. Good correlation was found between invasive FFR and FFRCT-2 cm and FFRCT-3 cm (r = 0.80, 95% CI, 0.70 to 0.87, p < 0.001; r = 0.82, 95% CI, 0.72 to 0.88, p < 0.001). Moderate correlation was found between invasive FFR and FFRCT-1 cm and FFRCT-lowest (r = 0.77, 95% CI, 0.65 to 0.85, p < 0.001; r = 0.78, 95% CI, 0.67 to 0.86, p < 0.001). FFRCT-1 cm + FFRCT-2 cm, FFRCT-2 cm + FFRCT-3 cm, FFRCT-3 cm + FFRCT-lowest, FFRCT-1 cm + FFRCT-2 cm + FFRCT-3 cm, and FFRCT-2 cm + FFRCT-3 cm + FFRCT-lowest were correatled with invasive FFR (r = 0.722; 0.722; 0.701; 0.722; and 0.722, respectively; p < 0.001 for all). Bland–Altman plots revealed a mild difference between invasive FFR and the four FFRCT (invasive FFR vs. FFRCT-1 cm, mean difference -0.0158, 95% limits of agreement: -0.1475 to 0.1159; invasive FFR vs. FFRCT-2 cm, mean difference 0.0001, 95% limits of agreement: -0.1222 to 0.1220; invasive FFR vs. FFRCT-3 cm, mean difference 0.0117, 95% limits of agreement: -0.1085 to 0.1318; and invasive FFR vs. FFRCT-lowest, mean difference 0.0343, 95% limits of agreement: -0.1033 to 0.1720). AUCs of CCTA, FFRCT-1 cm, FFRCT-2 cm, FFRCT-3 cm, and FFRCT-lowest in detecting lesion-specific ischemia were 0.578, 0.768, 0.857, 0.856 and 0.770, respectively. All FFRCT had a higher AUC than CCTA (all p < 0.05), FFRCT-2 cm achieved the highest AUC at 0.857. The AUCs of FFRCT-2 cm and FFRCT-3 cm were comparable (p > 0.05). The AUCs were similar between FFRCT-1 cm + FFRCT-2 cm, FFRCT-3 cm + FFRCT-lowest and FFRCT-2 cm alone (AUC = 0.857, 0.857, 0.857, respectively; p > 0.05 for all). The AUCs of FFRCT-2 cm + FFRCT-3 cm, FFRCT-1 cm + FFRCT-2 cm + FFRCT-3 cm, FFRCT-and 2 cm + FFRCT-3 cm + FFRCT-lowest (0.871, 0.871, 0.872, respectively) were slightly higher than that of FFRCT-2 cm alone (0.857), but without significnacne differences (p > 0.05 for all).ConclusionsFFRCT measured at 2 cm distal to the lower border of the target lesion is the optimal measurement site for identifying lesion-specific ischemia in patients with CAD.

Influence of Obesity on Coronary Artery Disease and Clinical Outcomes in the ADVANCE Registry.

The relationship between body size and cardiovascular events is complex. This study utilized the ADVANCE (Assessing Diagnostic Value of Noninvasive FFRCT in Coronary Care) Registry to investigate the association between body mass index (BMI), coronary artery disease (CAD), and clinical outcomes. The ADVANCE registry enrolled patients undergoing evaluation for clinically suspected CAD who had >30% stenosis on cardiac computed tomography angiography. Patients were stratified by BMI: normal <25 kg/m2, overweight 25-29.9 kg/m2, and obese ≥30 kg/m2. Baseline characteristics, cardiac computed tomography angiography and computed tomography fractional flow reserve (FFRCT), were compared across BMI groups. Adjusted Cox proportional hazards models assessed the association between BMI and outcomes. Among 5014 patients, 2166 (43.2%) had a normal BMI, 1883 (37.6%) were overweight, and 965 (19.2%) were obese. Patients with obesity were younger and more likely to have comorbidities, including diabetes and hypertension (all P<0.001), but were less likely to have obstructive coronary stenosis (65.2% obese, 72.2% overweight, and 73.2% normal BMI; P<0.001). However, the rate of hemodynamic significance, as indicated by a positive FFRCT, was similar across BMI categories (63.4% obese, 66.1% overweight, and 67.8% normal BMI; P=0.07). Additionally, patients with obesity had a lower coronary volume-to-myocardial mass ratio compared with patients who were overweight or had normal BMI (obese BMI, 23.7; overweight BMI, 24.8; and normal BMI, 26.3; P<0.001). After adjustment, the risk of major adverse cardiovascular events was similar regardless of BMI (all P>0.05). Patients with obesity in the ADVANCE registry were less likely to have anatomically obstructive CAD by cardiac computed tomography angiography but had a similar degree of physiologically significant CAD by FFRCT and similar rates of adverse events. An exclusively anatomic assessment of CAD in patients with obesity may underestimate the burden of physiologically significant disease that is potentially due to a significantly lower volume-to-myocardial mass ratio.

Comparison of prognostic value between CAD-RADS 1.0 and CAD-RADS 2.0 evaluated by convolutional neural networks based CCTA

ObjectivesThe aim of the present study was to investigate the prognostic value of the novel coronary artery disease reporting and data system (CAD-RADS) 2.0 compared with CAD-RADS 1.0 in patients with suspectedcoronary artery disease (CAD) evaluated by convolutional neural networks (CNN) based coronary computed tomography angiography (CCTA). MethodsA total of 1796 consecutive inpatients with suspected CAD were evaluated by CCTA for CAD-RADS 1.0 and CAD-RADS 2.0 classifications. Kaplan-Meier and multivariate Cox models were used to estimate major adverse cardiovascular events (MACE) inclusive of all-cause mortality or myocardial infarction (MI). The C-statistic was used to assess the discriminatory ability of the two classifications. ResultsIn total, 94 (5.2%) MACE occurred over the median follow-up of 45.25 months (interquartile range 43.53–46.63 months). The annualized MACE rate was 0.014 (95% CI: 0.011–0.017). Kaplan-Meier survival curves indicated that the CAD-RADS classification, segment involvement score (SIS) grade, and Computed Tomography Fractional Flow Reserve (CT-FFR) classification were all significantly associated with the increase in the cumulative MACE (all P < 0.001). CAD-RADS classification, SIS grade, and CT-FFR classification were significantly associated with endpoint in univariate and multivariate Cox analysis. CAD-RADS 2.0 showed a further incremental increase in the prognostic value in predicting MACE (c-statistic 0.702, 95% CI: 0.641–0.763, P = 0.047), compared with CAD-RADS 1.0. ConclusionsThe novel CAD-RADS 2.0 evaluated by CNN-based CCTA showed higher prognostic value of MACE than CAD-RADS 1.0 in patients with suspected CAD.

CT-derived fractional flow reserve for prediction of major adverse cardiovascular events in diabetic patients

ObjectivesTo investigate the prognostic value of computed tomography fractional flow reserve (CT-FFR) in patients with diabetes and to establish a risk stratification model for major adverse cardiac event (MACE).MethodsDiabetic patients with intermediate pre-test probability of coronary artery disease were prospectively enrolled. All patients were referred for coronary computed tomography angiography and followed up for at least 2 years. In the training cohort comprising of 957 patients, two models were developed: model1 with the inclusion of clinical and conventional imaging parameters, model2 incorporating the above parameters + CT-FFR. An internal validation cohort comprising 411 patients and an independent external test cohort of 429 patients were used to validate the proposed models.Results1797 patients (mean age: 61.0 ± 7.0 years, 1031 males) were finally included in the present study. MACE occurred in 7.18% (129/1797) of the current cohort during follow- up. Multivariate Cox regression analysis revealed that CT-FFR ≤ 0.80 (hazard ratio [HR] = 4.534, p < 0.001), HbA1c (HR = 1.142, p = 0.015) and low attenuation plaque (LAP) (HR = 3.973, p = 0.041) were the independent predictors for MACE. In the training cohort, the Log-likelihood test showed statistical significance between model1 and model2 (p < 0.001). The C-index of model2 was significantly larger than that of model1 (C-index = 0.82 [0.77–0.87] vs. 0.80 [0.75–0.85], p = 0.021). Similar findings were found in internal validation and external test cohorts.ConclusionCT-FFR was a strong independent predictor for MACE in diabetic cohort. The model incorporating CT-FFR, LAP and HbA1c yielded excellent performance in predicting MACE.

CRT-400.15 Computed Tomography Fractional Flow Reserve Discrepancies With Invasive Angiography and Physiology

CRT-400.15 Computed Tomography Fractional Flow Reserve Discrepancies With Invasive Angiography and Physiology

The Cost Effectiveness of Coronary CT Angiography and the Effective Utilization of CT-Fractional Flow Reserve in the Diagnosis of Coronary Artery Disease

Given the high global disease burden of coronary artery disease (CAD), a major problem facing healthcare economic policy is identifying the most cost-effective diagnostic strategy for patients with suspected CAD. The aim of this review is to assess the long-term cost-effectiveness of coronary computed tomography angiography (CCTA) when compared with other diagnostic modalities and to define the cost and effective diagnostic utilization of computed tomography-fractional flow reserve (CT-FFR). A search was conducted through the MEDLINE database using PubMed with 16 of 119 manuscripts fitting the inclusion and exclusion criteria for review. An analysis of the data included in this review suggests that CCTA is a cost-effective strategy for both low risk acute chest pain patients presenting to the emergency department (ED) and low-to-intermediate risk stable chest pain outpatients. For patients with intermediate-to-high risk, CT-FFR is superior to CCTA in identifying clinically significant stenosis. In low-to-intermediate risk patients, CCTA provides a cost-effective diagnostic strategy with the potential to reduce economic burden and improve long-term health outcomes. CT-FFR should be utilized in intermediate-to-high risk patients with stenosis of uncertain clinical significance. Long-term analysis of cost-effectiveness and diagnostic utility is needed to determine the optimal balance between the cost-effectiveness and diagnostic utility of CT-FFR.

Application of Dual-Source CT Using Iterative Reconstruction Technology Combined with CT-FFR Parameters in the Diagnosis of Coronary Heart Disease.

In order to achieve early detection of myocardial ischemia and improve the diagnosis of coronary heart disease (CHD), it is necessary to find a convenient, non-invasive and effective examination method. This study aimed to explore the application value of dual-source computed tomography (CT) by using advanced modeled iterative reconstruction (ADMIRE) combined with computed tomography-fractional flow reserve (CT-FFR) technique in CHD, which provides imaging basis for early diagnosis of CHD and myocardial ischemia. Seventy-five CHD patients were examined by coronary computed tomography angiography (CCTA). Their CCTA images were reconstructed by iterative algorithm in ADMIRE 1-5 using post-processing workstation. The standard deviation (SD), signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of proximal vascular images in right coronary artery (RCA), left main coronary artery (LM), left anterior descending artery (LAD) and left circumflex artery (LCX) were analyzed and compared. Invasive coronary angiography (ICA) was adopted in patients with ≥50% stenosis of coronary artery diameter. Taking ICA as the gold-standard method to accurately assess coronary arterial stenosis degree, the diagnostic efficiency of dual-source CT to diagnose coronary artery stenosis was analyzed. Some patients were subjected to myocardial CT perfusion (CTP) scanning and CT-FFR analysis, which facilitated analyzing the correlation and consistency between the diagnostic results of CTP and analysis results of CT-FFR. There was no statistical difference in the CT values of RCA, LM, LAD and LCX in groups with different ADMIRE reconstruction intensities (p > 0.05). But the noise, SNR and CNR interval were different among the iterative intensity groups (p < 0.05). Kappa consistency analysis was used to analyze the subjective evaluation results of image quality under different iterative reconstruction grades. The independent sample t-test performed on the subjective scores revealed that the scores on images were the best at ADMIRE 4. CCTA has sensitivity, specificity, positive predictive value, and negative predictive value of 91.52%, 97.59%, 97.98%, and 96.42% for identifying coronary artery stenosis, respectively. The diagnostic efficacy of CT-FFR, the Kappa analysis of myocardial CTP and CT-FFR results, which yields a Kappa value of 0.830 (p < 0.05). Spearman correlation analysis was used to statistically analyze the results of myocardial CTP and CT-FFR (correlation coefficient r = 0.774, p < 0.05). Diagnostic sensitivity and specificity were 93% and 95%, respectively. The dual-source CT using ADMIRE iterative algorithm has the best display of coronary vessels and higher image quality when the intensity is 4, and CT-FFR can be used as a non-invasive method for early detection of myocardial ischemia, which is worthy of clinical application.

Additional clinical impact of plaque analysis for on-site CT-derived FFR in coronary CT angiography on midterm prognosis

Abstract Background We previously reported that per-patient on-site computed tomography-fractional flow reserve (CT-FFR), which can be acquired on-site workstation using fluid structure interaction during the multiple optimal diastolic phases measured 1 to 2 cm distal to a target lesion may be feasible for risk stratification based on future cardiac events for patients who did not undergo planned revascularization. However, per-vessel CT-FFR and the additional impact of plaque analysis on CT-FFR have not been evaluated. Purpose The aim of this study is to assess the clinical and additional impact of novel plaque analysis using labeling method for per-vessel CT-FFR on midterm prognosis. Methods A total of 254 consecutive patients with 354 vessels showing 50–90% stenosis but not revascularized within 90 days from coronary CT angiography (CCTA) on 320-row CT were retrospectively analyzed and followed during a median follow up 3.6 years. Plaque characteristics by labeling method (necrotic core/total plaque volume (% necrotic core), non-calcified plaque (NCP)/vessel volume (%NCP), and total plaque/vessel volume (%total plaque) for both total vessel volume (mm3) and at minimum lumen area (MLA, mm2)), positive remodeling (PR) and CT-FFR were analyzed on per-target vessels. The endpoint was vessel oriented-composite outcome (VOCO), including cardiac death, non-fatal MI, and unplanned revascularization. Results The incidence of VOCO occurred in 6.8% (24/354). In the cox proportional hazard model, a multivariate analysis identified CT-FFR≤0.80 was the most associated factor with VOCO (all values &amp;lt;0.01 for other plaque morphologies), but %necrotic core, %NCP, %total plaque at MLA and PR were significantly independent of CT-FFR≤0.80. (%necrotic core HR; 3.43 (p&amp;lt;0.01 [95% confidence interval (CI) 1.42–8.29]), %NCP HR; 4.05 (p=0.03 [95% CI 1.19–13.71]), %total plaque at MLA HR; 2.82 (p=0.02 [95% CI 1.18–6.76]), and PR HR; 2.90 (p&amp;lt;0.01 [95% CI 1.30–6.51]), respectively.) Conclusion From a view point of clinical outcomes for vessels with moderate to severe stenosis but not revascularized at initial CCTA, CT-FFR demonstrated the significant impact on per-vessel analysis. Moreover, %necrotic core, %NCP and %total plaque at MLA analyzed by labeling method provided better prognostic value in addition to CT-FFR. Funding Acknowledgement Type of funding sources: None.

Feasibility and Comparison of Resting Full-Cycle Ratio and Computed Tomography Fractional Flow Reserve in Patients with Severe Aortic Valve Stenosis.

Background: Computed tomography derived Fractional Flow Reserve (CT-FFR) has been shown to decrease the referral rate for invasive coronary angiography (ICA). The purpose of the study was to evaluate the diagnostic performance of CT-FFR compared to hyperemia-free index Resting Full-cycle Ratio (RFR) in patients with relevant aortic stenosis (AS) and intermediate coronary stenosis. Methods: 41 patients with 46 coronary lesions underwent ICA with quantitative coronary angiography (QCA), pressure wire assessment and routine pre-transcatheter aortic valve replacement (TAVR) computed tomography (CT). CT-FFR analysis was performed using prototype on-site software. Results: RFR showed a significant correlation with CT-FFR (Pearson’s correlation, r = 0.632, p < 0.001). On a per-lesion basis, diagnostic accuracy, sensitivity, specificity, positive predictive value, and negative predictive value of CT-FFR were 82.6% (95% CI 68.6–92.2), 69.6% (95% CI 47.1–86.8), 95.7% (95% CI 78.1–99.9), 94.1% (95% CI 69.8–99.1), and 75.9% (95% CI 62.7–85.4), respectively. The optimal cutoff value of the CT-FFR for RFR ≤ 0.89 prediction was 0.815. The area under the receiver curve showed a larger area under the curve for CT-FFR (0.87; 95% CI 0.75–0.98) compared with CTA stenosis of ≥50% (0.54, 95% CI 0.38–0.71), CTA ≥ 70% (0.72, 95% CI 0.57–0.87) and QCA ≥ 50% (0.67, 95% CI 0.52–0.83). Conclusions: CT-FFR assessed by routine pre-TAVR CT is safe and feasible and shows a significant correlation with RFR in patients with AS. CT-FFR is superior to QCA ≥ 50%, CT ≥ 50% and CT ≥ 70% in assessing the hemodynamic relevance of intermediate coronary lesions. Thus, CT-FFR has the potential to guide revascularization in patients with AS.

Long-term prognostic value of the serial changes of CT-derived fractional flow reserve and perivascular fat attenuation index.

To investigate the serial changes of computed tomography (CT) fractional flow reserve (CT-FFR) and fat attenuation index (FAI), and explore their relationships with long-term clinical outcomes. Consecutive symptomatic patients with an intermediate pretest probability of coronary artery disease 1-4 were prospectively enrolled if coronary CT angiography (CCTA) revealed at least 1 lesion with 30-70% stenosis on major epicardial arteries. Follow-up CCTA was performed at 1 to 1.5-year intervals. All patients were further followed up after the second CCTA until September 2019. The Coronary Artery Disease - Reporting and Data System (CAD-RADS) grade, high-risk plaque features, lesion-specific CT-FFR, and FAI were measured for prognosis analysis. A total of 263 patients were included in the analysis, and 38 major adverse cardiac events (MACEs) occurred. In the MACE group, the lesion-specific CT-FFR decreased significantly at the follow-up CCTA [0.80 (0.74-0.90) versus 0.85 (0.76-0.93); P=0.01], whereas the FAI did not notably increase (-70.4±8.9 versus -71.3±7.1 HU; P=0.436). In the non-MACE group, lesion-specific CT-FFR increased markedly [0.91 (0.84-0.95) versus 0.90 (0.82-0.94); P<0.001], while the FAI decreased substantially (-74.0±10.8 versus -72.4±11.5 HU; P=0.004). Decreased CT-FFR (adjusted overall hazard ratio =2.455; P=0.023) and increased FAI (adjusted hazard ratio =2.956; P=0.002) were the strongest independent predictors of MACEs. Serial changes of CT-FFR and FAI provided incremental prognostic value (Concordance statistic =0.716; P=0.003; over conventional clinical and imaging parameters (Concordance statistic =0.762; P=0.004). Decreased CT-FFR and increased FAI at follow-up CCTA were the 2 strongest predictors of MACEs. Serial changes of CT-FFR and FAI provided incremental prognostic value over conventional clinical and imaging parameters for risk stratification. In addition, decreased CT-FFR provided incremental predictive value for MACEs from 15 months after second CCTA, while increased FAI added prognostic value from the second CCTA onwards.

Comparison of diagnostic performance in on-site based CT-derived fractional flow reserve measurements.

BackgroundComputed tomography fractional flow reserve (CT-FFR), which can be acquired on-site workstation using fluid structure interaction during the multiple optimal diastolic phase, has an incremental diagnostic value over conventional coronary computed tomography angiography (CCTA). However, the appropriate location for CT-FFR measurement remains to be clarified.MethodA total of 115 consecutive patients with 149 vessels who underwent CCTA showing 30–90% stenosis with invasive FFR within 90 days were retrospectively analyzed. CT-FFR values were measured at three points: 1 and 2 cm distal to the target lesion (CT-FFR1cm, 2cm) and the vessel terminus (CT-FFRlowest). The diagnostic accuracies of CT-FFR ≤ 0.80 for detecting hemodynamically significant stenosis, defined as invasive FFR ≤ 0.80, were compered.ResultFifty-five vessels (36.9%) had invasive FFR ≤ 0.80. The accuracy and AUC for CT-FFR1cm and 2cm were comparable, while the AUC for CT-FFRlowest was significantly lower than CT-FFR1cm and 2cm. (lowest/1cm, 2 cm = 0.68 (95 %CI 0.63–0.73) vs 0.79 (0.72–0.86, p = 0.006), 0.80 (0.73–0.87, p = 0.002)) The sensitivity and negative predictive value of CT-FFRlowest were 100%. The reclassification rates from positive CT-FFRlowest to negative CT-FFR1cm and 2cm were 55.7% and 54.2%, respectively.ConclusionThe diagnostic performance of CT-FFR was comparable when measured at 1-to-2 cm distal to the target lesion, but significantly higher than CT-FFRlowest. The lesion-specific CT-FFR could reclassify false positive cases in patients with positive CT-FFRlowest, while all patients with negative CT-FFRlowest were diagnosed as negative by invasive FFR.

Prevalence of pathological FFRCT values without coronary artery stenosis in an asymptomatic marathon runner cohort

ObjectivesTo evaluate computed tomography fractional flow reserve (FFRCT) values in distal parts of the coronaries in an asymptomatic cohort of marathon runners without any coronary stenosis for potentially false-positive values.MethodsNinety-eight asymptomatic male marathon runners (age 53 ± 7 years) were enrolled in a prospective monocentric study and underwent coronary computed tomography angiography (CCTA). CCTA data were analyzed for visual coronary artery stenosis. FFRCT was evaluated in 59 participants without coronary artery stenosis in proximal, mid, and distal coronary sections using an on-site software prototype.ResultsIn participants without coronary artery stenosis, abnormal FFRCT values ≤ 0.8 in distal segments were found in 22 participants (37%); in 19 participants in the LAD; in 5 participants in the LCX; and in 4 participants in the RCA. Vessel diameters in participants with FFRCT values > 0.80 compared to ≤ 0.80 were 1.6 ± 0.3 mm versus 1.5 ± 0.3 mm for distal LAD (p = 0.025), 1.8 ± 0.3 mm versus 1.6 ± 0.5 mm for distal LCX (p = 0.183), and 2.0 ± 0.4 mm versus 1.5 ± 0.2 mm for distal RCA (p < 0.001).ConclusionsAbnormal FFRCT values of ≤ 0.8 frequently occurred in distal coronary segments in subjects without any anatomical coronary artery stenosis. This effect is only to some degree explainable by small distal vessel diameters. Therefore, the validity of hemodynamic relevance evaluation using FFRCT in distal coronary artery segment stenosis is reduced.Key Points• Abnormal FFRCT values (≤ 0.8) occurred in over a third of the subjects in the distal LAD despite the absence of coronary artery stenosis..• Therefore, the validity of hemodynamic relevance evaluation in distal coronary artery segment stenosis is reduced.• Decision-making based on abnormal FFRCT values in distal vessel sections should be performed with caution and only in combination with visual assessment of the grade of stenosis..

Onsite Computed Tomography Fractional Flow Reserve in Patients with Suspected Stable Coronary Artery Disease Initial Experience.

Introduction Computed tomographic coronary angiographic (CTCA) has evolved into a robust technique to detect significant stenosis; however, there is a discordance in the anatomic and functional significance of stenosis. Therefore, patients with stable coronary artery disease need to be further evaluated before deciding for any revascularization procedure. Material and Methods A total of 100 consecutive patients of suspected stable coronary artery disease who underwent CTCA were evaluated for functional significance of lesions using onsite computed tomography fractional flow reserve (CTFFR) and the results were compared for detection of both significant and hemodynamically significant/severe stenosis on per vessel and per patient basis and differences were statistically analyzed. Impact of these differences were analyzed for the final outcome and management plan. Results CTCA detected 33 patients with severe stenosis, while 54 patients had hemodynamically significant stenosis on CTFFR. The sensitivity and specificity of CTCA for the detection of significant coronary artery stenosis per vessel basis were 97.7 and 93.3%, respectively, with a negative predictive value of 98.0%. For severe coronary artery stenosis, sensitivity, specificity, and negative and positive predictive values were 51.6, 89, 68.8, and 80%, respectively, on per vessel basis with CTCA. On per patient basis, CTCA showed as sensitivity and specificity of 61 and 84%, respectively, with area under curve (AUC) being 0.92 and 0.67 for significant and severe stenosis, respectively. Discussion Onsite CTFFR is a useful tool to calculate functionally significant stenosis and also improves the sensitivity and specificity of CTCA. CTFFR detected 12% more stenotic vessels in the present study on per vessel basis and 21% on per patient basis.

Added value of computed tomography fractional flow reserve in the diagnosis of coronary artery disease

Multiple non-invasive tests are performed to diagnose coronary artery disease (CAD), but all are limited to either anatomical or functional assessments. Computed tomography derived Fractional Flow Reserve (CT-FFR) based on patient-specific lumped parameter models is a new test combining both characteristics simulating invasive FFR. This study aims to evaluate the added value of CT-FFR over other non-invasive tests to diagnose CAD. Patients with clinical suspicion of angina pectoris between 2010 and 2011 were included in this cross-sectional study. All underwent stress electrocardiography (X-ECG), SPECT, CT coronary angiography (CCTA) and CT-FFR. Invasive coronary angiography (ICA) and FFR were used as reference standard. Five models mimicking the clinical workflow were fitted and the area under receiver operating characteristic (AUROC) curve was used for comparison. 44% of the patients included in the analysis had a FFR of ≤ 0.80. The basic model including pre-test-likelihood and X-ECG had an AUROC of 0.79. The SPECT-strategy had an AUROC of 0.90 (p = 0.008), CCTA-strategy of 0.88 (p < 0.001), 0.93 when adding CT-FFR (p = 0.40) compared to 0.94 when combining CCTA and SPECT. This study shows adding on-site CT-FFR based on patient-specific lumped parameter models leads to an increased AUROC compared to the basic model. It improves the diagnostic work-up beyond SPECT or CCTA and is non-inferior to the combined strategy of SPECT and CCTA in the diagnosis of hemodynamically relevant CAD.

Machine learning-based CT fractional flow reserve assessment in acute chest pain: first experience.

Computed tomography (CT)-derived fractional flow reserve (FFRCT) enables the non-invasive functional assessment of coronary artery stenosis. We evaluated the feasibility and potential clinical role of FFRCT in patients presenting to the emergency department with acute chest pain who underwent chest-pain CT (CPCT). For this retrospective IRB-approved study, we included 56 patients (median age: 62 years, 14 females) with acute chest pain who underwent CPCT and who had at least a mild (≥25% diameter) coronary artery stenosis. CPCT was evaluated for the presence of acute plaque rupture and vulnerable plaque features. FFRCT measurements were performed using a machine learning-based software. We assessed the agreement between the results from FFRCT and patient outcome (including results from invasive catheter angiography and from any non-invasive cardiac imaging test, final clinical diagnosis and revascularization) for a follow-up of 3 months. FFRCT was technically feasible in 38/56 patients (68%). Eleven of the 38 patients (29%) showed acute plaque rupture in CPCT; all of them underwent immediate coronary revascularization. Of the remaining 27 patients (71%), 16 patients showed vulnerable plaque features (59%), of whom 11 (69%) were diagnosed with acute coronary syndrome (ACS) and 10 (63%) underwent coronary revascularization. In patients with vulnerable plaque features in CPCT, FFRCT had an agreement with outcome in 12/16 patients (75%). In patients without vulnerable plaque features (n=11), one patient showed myocardial ischemia (9%). In these patients, FFRCT and patient outcome showed an agreement in 10/11 patients (91%). Our preliminary data show that FFRCT is feasible in patients with acute chest pain who undergo CPCT provided that image quality is sufficient. FFRCT has the potential to improve patient triage by reducing further downstream testing but appears of limited value in patients with CT signs of acute plaque rupture.

Contrast Fractional Flow Reserve (cFFR) and Computed Tomography Fractional Flow Reserve (CT-FFR) Guidance for Percutaneous Coronary Intervention (PCI)

In this review, we summarize both contrast fractional flow reserve (cFFR) and computed tomography fractional flow reserve (CT-FFR) as novel modalities to evaluate the hemodynamic significance of coronary artery stenoses and to guide percutaneous coronary intervention (PCI). Implementation of cFFR can reduce the time, cost, effort, and patient discomfort associated with traditional adenosine FFR. Clinical outcomes following cFFR-guided revascularization are currently under investigation. Emerging data on the use of CT-FFR in patients with acute coronary syndromes may increase the use of this technology in acute settings, while virtual stenting applications to model the hemodynamic results of stent placement may help optimize PCI planning. Using contrast media already available for traditional angiography, cFFR yields results that are highly reproducible and correlate more closely with traditional adenosine FFR than the distal/aortic pressure ratio (Pd/Pa) or the instantaneous wave-free ratio (iFR). Based upon computational fluid dynamics, CT-FFR provides a non-invasive estimate of the traditional adenosine FFR and predicts ischemia more accurately than nuclear imaging. Therefore, CT-FFR has begun to take on a gatekeeper role to minimize unnecessary invasive angiography.