Wire-based Fractional Flow Reserve Research Articles

The prognostic value of angiography-based vessel fractional flow reserve after percutaneous coronary intervention: The FAST Outcome study

BackgroundVessel Fractional Flow Reserve (vFFR) as assessed by three-dimensional quantitative coronary angiography has high correlation with pressure wire-based fractional flow reserve in both a pre- and post-PCI setting. The present study aims to assess the prognostic value of post-PCI vFFR on the incidence of target vessel failure (TVF), a composite endpoint of cardiac death, target vessel myocardial infarction and target vessel revascularization (TVR) at 5-year follow up. MethodsPost-PCI vFFR was calculated after routine PCI in a total of 748 patients (832 vessels) with available orthogonal angiographic projections of the stented segment. ResultsMedian age was 65 (IQR 55–74) years, 18.2% were diabetic, and 29.1% presented with stable angina. Median post-PCI vFFR was 0.91 (IQR 0.86–0.95). Vessels were categorized into tertiles based on post-PCI vFFR: low (vFFR <0.88), middle (vFFR 0.88–0.93), and upper (vFFR ≥0.94). Vessels in the lower and middle tertile were more often LADs and had smaller stent diameters (p<0.001). Vessels in the lower and middle tertile had a higher risk of TVF as compared to vessels in the upper tertile (24.6% and 21.5% vs. 17.1%; adjusted HR 1.84 (95%CI 1.15–2.95), p = 0.011, and 1.58 (95%CI 1.02–2.45), p = 0.040) at 5-years follow-up. Additionally, vessels in the lower tertile had higher rates of TVR as compared to vessels in the higher tertile (12.6% vs. 6.5%, adjusted HR 1.93 (95%CI 1.06–3.53), p = 0.033). ConclusionLower post-PCI vFFR values are associated with a significantly increased risk of TVF and TVR at 5-years follow-up.

Vessel fractional flow reserve (vFFR) for the assessment of stenosis severity: the FAST II study.

Fractional flow reserve (FFR)-guided percutaneous coronary intervention (PCI) is superior to angiography-guided PCI. The clinical uptake of FFR has been limited, however, by the need to advance a wire in the coronary artery, the additional time required and the need for hyperaemic agents which can cause patient discomfort. FFR derived from routine coronary angiography eliminates these issues. The aim of this study was to assess the diagnostic performance and accuracy of three-dimensional quantitative coronary angiography (3D-QCA)-based vessel FFR (vFFR) compared to pressure wire-based FFR (≤0.80). The FAST II (Fast Assessment of STenosis severity) study was a prospective observational multicentre study designed to evaluate the diagnostic accuracy of vFFR compared to the reference standard (pressure wire-based FFR ≤0.80). A total of 334 patients from six centres were enrolled. Both site-determined and blinded independent core lab vFFR measurements were compared to FFR. The core lab vFFR was 0.83±0.09 and pressure wire-based FFR 0.83±0.08. A good correlation was found between core lab vFFR and pressure wire-based FFR (R=0.74; p<0.001; mean bias 0.0029±0.0642). vFFR had an excellent diagnostic accuracy in identifying lesions with an invasive wire-based FFR ≤0.80 (area under the curve [AUC] 0.93; 95% confidence interval [CI]: 0.90-0.96; p<0.001). Positive predictive value, negative predictive value, diagnostic accuracy, sensitivity and specificity of vFFR were 90%, 90%, 90%, 81% and 95%, respectively. 3D-QCA-based vFFR has excellent diagnostic performance to detect FFR ≤0.80. The study was registered on clinicaltrials.gov under identifier NCT03791320.

Diagnostic performance of fractional flow reserve derived from coronary angiography, intravascular ultrasound, and optical coherence tomography; a meta-analysis

BackgroundLittle is known about the overall diagnostic performance of computational fractional flow reserve (FFR) derived from angiography (Angio-FFR), intravascular ultrasound (IVUS-FFR), and optical coherence tomography (OCT-FFR) to detect hemodynamically significant coronary artery disease. The present study aimed to evaluate the diagnostic performance of those novel physiologic indices using conventional FFR as the gold standard. MethodsPubMed and Embase were searched in September 2021 for a systematic review and meta-analysis of studies assessing the diagnostic performance of invasive imaging-derived FFR. The primary outcomes were the summary sensitivity, specificity, correlation coefficients of each index. ResultsA total of 6572 records were initially identified and 49 studies were included in the final analysis (7010 lesions from 36 studies for Angio-FFR, 305 lesions from 5 studies for IVUS-FFR, and 667 lesions from 8 studies for OCT-FFR). Invasive imaging-derived FFR had a high diagnostic performance to detect functionally significant coronary lesions using conventional FFR as the gold standard [Angio-FFR, sensitivity 0.87 (95% CI 0.84–0.89), specificity 0.93 (95% CI 0.910.95); IVUS-FFR, sensitivity 0.90 (95% CI 0.84–0.94), specificity 0.95 (95% CI 0.90–0.98); OCT-FFR, sensitivity 0.85 (95% CI 0.78–0.91), specificity 0.93 (95% CI 0.89–0.95)]. The summary correlation coefficients of Angio-, IVUS-, and OCT-FFRs with wire-based FFR were 0.83 (95% CI 0.80–0.85), 0.85 (95% CI 0.79–0.91), and 0.80 (95% CI 0.74–0.86), respectively. ConclusionsThis meta-analysis demonstrated that computational FFR derived from invasive coronary imaging has clinically acceptable diagnostic performances irrespective of modalities, supporting their applicability to clinical practice.

WITHDRAWN: Diagnostic Accuracy of CT-derived and Angiogram-derived Fractional Flow Reserve

Although accumulating evidence demonstrated that virtual fractional flow reserve (FFR) based on coronary computed tomography angiography (CCTA) (CT-FFR) or invasive coronary angiogram (ICA) (CA-FFR) are promising alternatives to wire based FFR, which method has better diagnostic accuracy was still unclear. In our study, we aim to directly compare the diagnostic performance of CT-FFR and CA-FFR. During the period of September 2019 to December 2020, patients with at least one 30%-90% coronary artery stenosis were enrolled and received invasive FFR. Then, virtual FFR values were calculated based on both CCTA and ICA, and then compared with the invasive FFR value. Invasive FFR measurements were successfully performed in 114 vessels of 96 patients. Both CT-FFR and CA-FFR showed good correlation with wire-based FFR, with r values of 0.84 and 0.71 respectively. In paired t-test, the deviation of CT-FFR and CA-FFR was not significantly different (t = -1.9083, p = 0.05889). In Bland-Altman analysis, the coefficients of variation were 8.4% and 13.2% for CT-FFR and CA-FFR respectively. In ROC curve analysis, the per-vessel diagnostic accuracy of CT-FFR and CA-FFR was 94.7% and 92.1% respectively. The area under the curve of CT-FFR was slightly higher than that of CA-FFR (0.986 and 0.916 respectively, the difference between areas = 0.070, 95% CI 0.003-0.137, p = 0.0227). Both CT-FFR and CA-FFR had good diagnostic concordance with wire-based FFR. In ROC Curve analysis, CT-FFR demonstrated slightly higher diagnostic accuracy than CA-FFR. URL: https://www.chictr.org.cn/showproj.aspx?proj=44719. Unique Identifier: ChiCTR1900026971.

Diagnostic concordance and discordance between angiography-based quantitative flow ratio and fractional flow reserve derived from computed tomography in complex coronary artery disease

BackgroundBoth quantitative flow ratio (QFR) and fractional flow reserve derived from computed tomography (FFRCT) have shown significant correlations with invasive wire-based fractional flow reserve. However, the correlation between QFR and FFRCT is not fully investigated in patients with complex coronary artery disease (CAD). The aim of this study is to investigate the correlation and agreement between QFR and FFRCT in patients with de novo three-vessel disease and/or left main CAD. MethodsThis is a post-hoc sub-analysis of the international, multicenter, and randomized SYNTAX III REVOLUTION trial, in which both invasive coronary angiography and coronary computed tomography angiography were prospectively obtained prior to the heart team discussion. QFR was performed in an independent core laboratory and compared with FFRCT analyzed by HeartFlow™. The correlation and agreement between QFR and FFRCT were assessed per vessel. Furthermore, independent factors of diagnostic discordance between QFR and FFRCT were evaluated. ResultsOut of 223 patients, 40 patients were excluded from this analysis due to the unavailability of FFRCT and/or QFR, and a total of 469 vessels (183 patients) were analyzed. There was a strong correlation between QFR and FFRCT (R ​= ​0.759; p ​< ​0.001), and the Bland-Altman analysis demonstrated a mean difference of −0.005 and a standard deviation of 0.116. An independent predictor of diagnostic concordance between QFR and FFRCT was the lesion location in right coronary artery (RCA) (odds ratio 0.395; 95% confidence interval 0.174–0.894; P ​= ​0.026). ConclusionIn patients with complex CAD, QFR and FFRCT were strongly correlated. The location of the lesion in RCA was associated with the highest diagnostic concordance between QFR and FFRCT.

Prognostic value of a novel index: computational pressure-flow dynamics derived fractional flow reserve in patients with stable coronary artery disease treated with optimal medical therapy alone

Abstract Background The use of fractional flow reserve (FFR) is limited due to the need of invasive pressure wire and hyperaemic stimulus. Computational pressure-flow dynamics derived fractional flow reserve (caFFR) is a novel non-invasive index to determine the FFR in patients with stable coronary artery disease (CAD). Purpose The clinical value of caFFR remains uncertain. The aim of the study is to evaluate the prognostic role of caFFR in patients with stable CAD who were treated by optimal medical therapy alone. Methods A total of 558 stable CAD patients (mean age=64.5±11.2, 59.0% male) with ≥1 coronary lesion detected during conventional coronary angiogram were included. All of them did not undergo percutaneous coronary intervention and were treated with optimal medical therapy alone. Patients were then classified into 4 groups according to their caFFR value; caFFR ≤0.70 (n=40), caFFR = 0.71–0.80 (n=28), caFFR = 0.81–0.90 (n=292), caFFR = 0.91–1.00 (n=198), with a lower caFFR indicating a greater magnitude of myocardial ischemia. The primary endpoint was 3-year major adverse cardiac events (MACE), defined as a composite of all-cause mortality, myocardial infarction or any unplanned revascularization. Results During a median follow-up of 36 months, a total of 49 composite events occurred, including 27 all-cause mortality, 4 myocardial infarction and 18 unplanned revascularization. After multivariate adjustment, caFFR was an independent predictor of MACE (adjusted hazard ratio [HR] = 0.97 per 0.01 increase in caFFR; 95% confidence interval [Cl], 0.95–0.99; P&amp;lt;0.01), all-cause mortality (adjusted HR = 0.96 per 0.01 increase in caFFR; 95% Cl, 0.94–0.99; P&amp;lt;0.01), and stroke (adjusted HR = 0.95 per 0.01 increase in caFFR; 95% Cl, 0.90–0.99; P=0.03). The area under the curve (AUC) by receiver-operating characteristic curve analysis (ROC) is 0.70 (95% Cl, 0.62–0.78; P&amp;lt;0.01). The optimal cut-off of caFFR defined by ROC analysis for predicting MACE is 0.80, concluding that patients with caFFR ≤0.80 have significantly higher adverse event rate, which is consistent with the cut-off from wire-based FFR. Using caFFR = 0.91–1.00 as reference, the risk of MACE was highest in patients with caFFR ≤0.70 (adjusted HR = 4.65; 95% Cl, 1.81–11.94; P&amp;lt;0.01), followed by caFFR = 0.71–0.80 (adjusted HR = 3.67; 95% Cl, 1.12–11.33; P=0.02). The risk of MACE was nonetheless similar among patients with caFFR &amp;gt;0.8 (adjusted HR = 1.39; 95% Cl, 0.61–3.19, P=0.44). Conclusion In patients with stable CAD who were treated with optimal medical therapy alone, those with more significant myocardial ischemia, indicated by lower caFFR, had higher risks of adverse outcomes. The finding thus supports the use of this non invasive index to quantify the severity of myocardial ischemia, improve risk-stratification, and predict adverse outcomes in patients with stable CAD. Funding Acknowledgement Type of funding sources: Public hospital(s). Main funding source(s): The University of Hong Kong, Queen Mary Hospital

Association between non-wire based computational angiography fractional flow reserve treatment threshold and major adverse cardiac events in patients with stable coronary artery disease

Abstract Introduction Despite class IA guideline recommendations, the use of fractional flow reserve (FFR) in guiding percutaneous coronary intervention (PCI) in stable coronary artery disease (CAD) patients remains low due to limitations including the need of guidewire placement and hyperaemic stimulus. A novel non-invasive index, computational pressure-flow dynamics derived FFR (caFFR), was developed for measuring functional myocardial ischemia and overcoming the limitations of FFR. However, the clinical relevance of caFFR remains to be investigated. In the present study, we aim at evaluating the prognostic value of caFFR among stable CAD patients. Methods We retrospectively included patients with stable CAD who underwent coronary angiography during 2014–2016 at our center. Based on the caFFR value, patients were considered to be ischemic (caFFR ≤0.8) and non-ischemic (caFFR &amp;gt;0.8). Further, we recombined the patients to form the adherence cohort, where patients were defined as adherent-to-caFFR if they were ischemic with PCI or non-ischemic without PCI, and nonadherent-to-caFFR if they were ischemic without PCI or non-ischemic with PCI. The primary endpoint was major adverse cardiac events (MACE), defined as a composite of all-cause mortality, non-fatal myocardial infarction, and any revascularization. Inverse probability of treatment weighting was used to account for treatment selection bias (PCI vs without PCI, or adherent vs non-adherent), and Cox proportional hazard model was used to evaluate the association with MACE. Results A total of 1322 patients, 782 patients in the ischemic cohort and 540 patients in the non-ischemic cohort respectively, were included in our analysis. PCI was associated with a lower risk of MACE in the ischemic cohort (hazard ratio [HR] 0.52; 95% confidence interval [CI], 0.34–0.80; P=0.002), but was not associated with MACE in the non-ischemic cohort. In the adherence cohort, adherent-to-caFFR group (n=803) had a lower risk of MACE compared with nonadherent-to-caFFR group (n=566) (HR, 0.61; 95% CI, 0.44–0.85; P=0.003). Conclusion Our study is the first to demonstrate the prognostic value of caFFR, a non-wire based assessment of myocardial ischemia, in patients with stable CAD undergoing PCI. These findings support the use of caFFR that bears the potential of a wider adoption compared with wire-based FFR through a reduction in procedure time, risk and costs. Funding Acknowledgement Type of funding sources: None. Weighted Kaplan-Meier curvesWeighted Cox proportional hazards model

Discordant resting and hyperaemic coronary physiology among unselected patients referred for coronary angiography: a single centre experience

Abstract Background Physiological assessment of intermediate coronary artery lesions to guide therapy is well established. Recently, the use of non-hyperaemic pressure ratios (NHPRs) has been suggested as a reliable alternative to hyperaemic assessment, such as fractional flow reserve (FFR). However certain patient / lesion subsets, including proximal lesion location, young patient age and assessment of non-LAD vessels, have been associated with discordance of resting and hyperaemic measurements which has led to some confusion over their interpretation and integration into routine clinical practice. Purpose To evaluate the frequency of discordant resting and hyperaemic measurements among patients undergoing assessment of intermediate coronary artery stenoses, and to identify common lesion-specific features within patients with discordant data. Methods From our coronary physiology database, we identified consecutive lesions which had been assessed between October 2020 and March 2021 with both resting (resting full-cycle ratio; RFR) and hyperaemic (wire-based FFR with peripheral adenosine) indices. Positive RFR defined as &amp;lt;0.89 (negative RFR &amp;gt;0.93, grey zone RFR 0.89–0.93). Positive FFR defined as &amp;lt;0.80 (negative FFR ≥0.80). Concordance between measurements was assessed: Group 1 (RFR -ve, FFR +ve: positive discordance); Group 2 (RFR -ve, FFR -ve: normal concordance), Group 3 (RFR +ve, FFR +ve: abnormal concordance) and Group 4 (RFR +ve, FFR -ve: negative discordance). Results 100 lesions were identified as being assessed with both RFR and FFR, in 83 patients (67% male), mean age 67 (±12) years, vessel assessed; LAD 66, RCA 19, LCx 13, LMCA 1 and radial graft 1; with 45 being proximal lesions. 30 RFR measurements were in the grey zone. Of the remaining 70 lesions, 55 results (79%) were concordant (Group 2 = 31, Group 3 = 24), with 15 results (21%) being discordant (Group 1 = 3, Group 4 = 12). Negative predictive value (NPV) of RFR (for FFR &amp;lt;0.80) was 91%, when grey zone RFR measurements were excluded. Discordance was not related to age (69 vs 68 years, p=0.75), lesion location (proximal lesion with discordance (6/15) vs proximal lesion with concordance (27/55), p=0.91, figure 1) or non-LAD vessel (non-LAD with discordance (9/15) vs non-LAD lesion with concordance (20/55), p=0.77, figure 2). Conclusion Overall within our patient group, there appeared to be a good association of RFR to FFR. In particular, RFR had a high NPV for an FFR &amp;lt;0.80. The clinical relevance of discordant measurements requires further investigation. However, our data suggest that a positive RFR (&amp;lt;0.89) measurement may not always correlate with a significant FFR measurement (&amp;lt;0.80), and the mechanism for this is unclear. Consequently, caution should be applied when including these measures in every day practice, in particular within patients with a positive RFR measurement. Funding Acknowledgement Type of funding sources: None.

Agreement Between Invasive Wire-Based and Angiography-Based Vessel Fractional Flow Reserve Assessment on Intermediate Coronary Stenoses.

Background: Angiography-based functional assessment of coronary stenoses emerges as a novel approach to assess coronary physiology. We sought to investigate the agreement between invasive coronary wire-based fractional flow reserve (FFR), resting full-cycle ratio (RFR), and angiography-based vessel FFR (vFFR) for the functional assessment of coronary stenoses in patients with coronary artery disease.Materials and Methods: Between Jan 01, 2018, and Dec 31, 2020, 298 patients with 385 intermediate lesions received invasive coronary wire-based functional assessment (FFR, RFR or both) at a single tertiary medical center. Coronary lesions involving ostium or left main artery were excluded. vFFR analysis was performed retrospectively based on aortic root pressure and two angiographic projections.Results: In total, 236 patients with 291 lesions were eligible for vFFR analysis. FFR and RFR were performed in 258 and 162 lesions, respectively. The mean FFR, RFR and vFFR value were 0.84 ± 0.08, 0.90 ± 0.09, and 0.83 ± 0.10. vFFR was significantly correlated with FFR (r = 0.708, P < 0.001) and RFR (r = 0.673, P < 0.001). The diagnostic performance of vFFR vs. FFR was accuracy 81.8%, sensitivity 77.4%, specificity 83.9%, positive predictive value 69.9%, and negative predictive value 88.5%. The discriminative power of vFFR for FFR ≤ 0.80 or RFR ≤ 0.89 was excellent. Area under the receiver operating characteristic curve (AUC) was 0.87 (95% CI:0.83–0.92) for FFR and 0.80 (95% CI:0.73–0.88) for RFR.Conclusion: Angiography-based vFFR has a substantial agreement with invasive wire-based FFR and RFR in patients with intermediate coronary stenoses. vFFR can be utilized to assess coronary physiology without a pressure wire in a post hoc manner.

Agreement of Angiography-Derived and Wire-Based Fractional Flow Reserves in Percutaneous Coronary Intervention.

Background: Coronary angiography-derived fractional flow reserve (caFFR) measurements have shown good correlations and agreement with invasive wire-based fractional flow reserve (FFR) measurements. However, few studies have examined the diagnostic performance of caFFR measurements before and after percutaneous coronary intervention (PCI). This study sought to compare the diagnostic performance of caFFR measurements against wire-based FFR measurements in patients before and after PCI.Methods: Patients who underwent FFR-guided PCI were eligible for the acquisition of caFFR measurements. Offline caFFR measurements were performed by blinded hospital operators in a core laboratory. The primary endpoint was the vessel-oriented composite endpoint (VOCE), defined as a composite of vessel-related cardiovascular death, vessel-related myocardial infarction, and target vessel revascularization.Results: A total of 105 pre-PCI caFFR measurements and 65 post-PCI caFFR measurements were compared against available wire-based FFR measurements. A strong linear correlation was found between wire-based FFR and caFFR measurements (r = 0.77; p < 0.001) before PCI, and caFFR measurements also showed a high correlation (r = 0.82; p < 0.001) with wire-based FFR measurements after PCI. A total of 6 VOCEs were observed in 61 patients during follow-up. Post-PCI FFR values (≤0.82) in the target vessel was the strongest predictor of VOCE [hazard ratio (HR): 5.59; 95% confidence interval (CI): 1.12–27.96; p = 0.036). Similarly, patients with low post-PCI caFFR values (≤0.83) showed an 8-fold higher risk of VOCE than those with high post-PCI caFFR values (>0.83; HR: 8.83; 95% CI: 1.46–53.44; p = 0.017).Conclusion: The study showed that the caFFR measurements were well-correlated and in agreement with invasive wire-based FFR measurements before and after PCI. Similar to wire-based FFR measurements, post-PCI caFFR measurements can be used to identify patients with a higher risk for adverse events associated with PCI.

Accuracy of Intravascular Ultrasound-Based Fractional Flow Reserve in Identifying Hemodynamic Significance of Coronary Stenosis.

Ultrasonic flow ratio (UFR) is a novel method for fast computation of fractional flow reserve (FFR) from intravascular ultrasound images. The objective of this study is to evaluate the diagnostic performance of UFR using wire-based FFR as the reference. Post hoc computation of UFR was performed in consecutive patients with both intravascular ultrasound and FFR measurement in a core lab while the analysts were blinded to FFR. A total of 167 paired comparisons between UFR and FFR from 94 patients were obtained. Median FFR was 0.80 (interquartile range, 0.68-0.89) and 50.3% had a FFR≤0.80. Median UFR was 0.81 (interquartile range, 0.69-0.91), and UFR showed strong correlation with FFR (r=0.87; P<0.001). The area under the curve was higher for UFR than intravascular ultrasound-derived minimal lumen area (0.97 versus 0.89, P<0.001). The diagnostic accuracy, sensitivity, specificity, positive predictive value, negative predictive value, positive likelihood ratio, and negative likelihood ratio for UFR to identify FFR≤0.80 was 92% (95% CI, 87-96), 91% (95% CI, 82-96), 96% (95% CI, 90-99), 96% (95% CI, 89-99), 91% (95% CI, 93-96), 25.0 (95% CI, 8.2-76.2), and 0.10 (95% CI, 0.05-0.20), respectively. The agreement between UFR and FFR was independent of lesion locations (P=0.48), prior myocardial infarction (P=0.29), and imaging catheters (P=0.22). Intraobserver and interobserver variability of UFR analysis was 0.00±0.03 and 0.01±0.03, respectively. Median UFR analysis time was 102 (interquartile range, 87-122) seconds. UFR had a strong correlation and good agreement with FFR. The fast computational time and excellent analysis reproducibility of UFR bears the potential of a wider adoption of integration of coronary imaging and physiology in the catheterization laboratory.

Alternative methods for functional assessment of intermediate coronary lesions.

Wire-based fractional flow reserve (FFR) is a diagnostic tool used to evaluate the ischemic burden of coronary lesions. Large-scale studies have shown that FFR-guided revascularization is associated with better clinical outcomes. However, wide adoption of this technology is limited due to the considerable cost, additional time needed for set-up and performance of the measurement as well as the invasiveness of the procedure which requires pressure wire placement across the lesion into the distal segment of the coronary artery. To overcome these limitations new, promising, and less-/non-invasive methods were developed. These methods are based on computational fluid dynamics analysis and three-dimensional lumen reconstruction. The aim of this paper is to review scientific evidence supporting the clinical safety and efficacy of these techniques, such as instantaneous wave-free ratio, quantitative flow ratio and FFR calculated from computed tomographic angiography.

Optical coherence tomography-based machine learning for predicting fractional flow reserve in intermediate coronary stenosis: a feasibility study

Machine learning approaches using intravascular optical coherence tomography (OCT) to predict fractional flow reserve (FFR) have not been investigated. Both OCT and FFR data were obtained for left anterior descending artery lesions in 125 patients. Training and testing groups were partitioned in the ratio of 5:1. The OCT-based machine learning-FFR was derived for the testing group and compared with wire-based FFR in terms of ischemia diagnosis (FFR ≤ 0.8). The OCT-based machine learning-FFR showed good correlation (r = 0.853, P < 0.001) with the wire-based FFR. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of the OCT-based machine learning-FFR for the testing group were 100%, 92.9%, 87.5%, 100%, and 95.2%, respectively. The OCT-based machine learning-FFR can be used to simultaneously acquire information on both image and functional modalities using one procedure, suggesting that it may provide optimized treatments for intermediate coronary artery stenosis.

Diagnostic reliability of quantitative flow ratio for detection of myocardial ischemia compared with other angiographic and experience-dependent visual predicted indices

Abstract Background Quantitative flow ratio (QFR) is an image-based virtual fractional flow reserve (FFR) computed by three dimensional quantitative coronary angiography (3D-QCA) and estimated flow velocity. Several studies have reported that QFR had a good diagnostic performance as compared with wire-based FFR or instantaneous wave-free ratio (iFR). Purpose We compared the diagnostic reliability of QFR for detection of myocardial ischemia with other angiographic and visual predicted indices. Methods In 301 coronary lesions (263 patients) from our QFR database for previously-reported two studies, the diagnostic reliability of QFR, several angiographic and visual predicted indices were investigated using ROC analysis as reference of FFR≤0.8 or iFR≤0.89. Visual predicted FFR were estimated by 3 physicians (25-year experienced expert, 10-year experienced senior physician and 3-year experienced trainee) blinded to other indices. Results Area under the curve (AUC) of each index in ROC analysis is shown in Table. Conclusion QFR was reliable index detecting myocardial ischemia compared with other angiographic and experience-dependent visual predicted indices. Funding Acknowledgement Type of funding source: None

Machine learning for predicting fractional flow reserve based on optical coherence tomography in intermediate coronary stenosis

Abstract Background Machine learning approaches using intravascular optical coherence tomography (OCT) to predict fractional flow reserve (FFR) have not been previously investigated. The objective of the study was to evaluate a machine learning method to estimate FFR based on intravascular OCT images in intermediate coronary lesions. Methods Data from both OCT- and wire-based FFR methods were obtained for lesions of the left anterior descending artery in 125 patients. Based on the total number of lesions, training and testing groups were partitioned at a ratio of 5:1. For the training group, 36 features, including 16 clinical and lesion characteristics, and 21 OCT features, were used to model machine learning-FFR. machine learning-FFR values were then derived for the testing group and compared with wire-based FFR values in terms of a diagnosis of ischemia (FFR &amp;lt;0.8). Results Clinical and lesion characteristics and OCT features between the training and testing groups were similar. During the machine learning modeling of the training group, six important features of machine learning-FFR were identified: minimal luminal area, percentage of the stenotic area, lesion length, proximal luminal area, pre-procedural platelet count, and hypertension. machine learning-FFR values showed a good correlation (r=0.853, P&amp;lt;0.001) with wire-based FFR values (Figure 1A). The diagnostic power of an FFR value less than 0.8, sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of machine learning-FFR values for the testing group were 85.7%, 100%, 100%, 77.8%, and 90.5%, respectively (Figure 1B). Additionally, OCT-based machine learning-FFR values showed a good diagnostic accuracy compared with other image-based FFR values. Conclusions The OCT-based machine learning-FFR method can be used to simultaneously acquire information on both image and functional modalities using one invasive procedure, suggesting that it may be used to optimize treatments for intermediate coronary artery stenosis, as well as save time and cost. Funding Acknowledgement Type of funding source: Public grant(s) – National budget only. Main funding source(s): Funded by the Korean government (MSIT) (no. 2017R1A2B2003191)

The imortance of hyperemic contrast velocity assessment on image-based fractional flow reserve calculation

Abstract Aims Image-based fractional flow reserve (FFR) calculations reported good agreement with FFR measured invasively. The purpose of this study was to perform a retrospective analysis of the cases of a previous study on less invasive FFR calculation (simple FFR: FFRsim) as a simple calculation from hyperemic contrast flow data and three-dimensional coronary parameters. Methods and results We aimed to analyze the relations between the pressure wire-based FFR (FFRmeas) and fixed FFRsim: calculated from the fixed hyperemic velocity, rest FFRsim: calculated using the non-hyperemic frame count data to extrapolate the hyperemic velocity (based on the database used in the FAVOR1 study) hyp FFRsim: the hyperemic velocity derived from the frame count assessment during vasodilation.To calculate the frame count reserve (CFRFC) the resting frame count was divided by the hyperemic frame count; this value was then used to determine the CFRFC/FFRmeas ratio as an indicator of microvascular function in the corresponding myocardial area of the measured coronary vessel. A total of 50 lesions with intermediate stenosis were investigated. Correlation between rest FFRsim (from the resting frame count extrapolated to the hyperemic velocity) and FFRmeas was lower than the correlation between hyp FFRsim and FFRmeas (r=0.761 vs. 0.824). Based on ROC curve analysis for predicting the abnormal FFR of ≤0.80 the AUC were significantly higher for the hyperemia-based parameter than those calculated from resting frame counts. Significantly higher AUC were detected by the hyp FFRsim than by the rest FFRsim: 0.936 (95% CI: 0.828 to 0.985) vs. 0.862 (CI: 0.734 to 0.943); p=0.011. Linear regression analyses between the FFRsim (either by fixed FFRsim or by rest FFRsim or by hyp FFRsim methods) and the FFRmeas showed higher intercepts and less steep of the slopes in the subgroups with presence of microvascular disease defined as CFRFC/FFRmeas &amp;lt;2 than in those without microvascular disease (CFRFC/FFRmeas &amp;gt;2); the difference reached significant level (p=0.019) when calculated by rest FFRsim. Conclusions Hyperemic challenge either by adenosine or regadenoson is required for exact image-based FFR calculation especially in cases of suspicion for microvascular coronary disease. Funding Acknowledgement Type of funding source: None

Long-term serial functional evaluation after implantation of the Fantom sirolimus-eluting bioresorbable coronary scaffold.

Quantitative flow ratio (QFR) has been validated as an accurate surrogate of standard wire-based fractional flow reserve. The clinical and angiographic outcomes of the Fantom sirolimus-eluting bioresorbable coronary scaffold (BRS) have been previously studied and reported. We investigate the functional performance of the Fantom BRS. The FANTOM II trial prospectively enrolled 240 patients with stable coronary artery disease or unstable angina, of which 235 patients received the Fantom BRS and were included in the present analysis. We performed an independent serial QFR analysis of the target vessel at baseline, post-percutaneous coronary intervention (PCI), and at 6- or 9-month and 24-month follow-up, using a QFR threshold ≤0.80 to define functional ischemia. QFR was analyzable in 178 patients at baseline, 185 post-PCI, 178 at 6- or 9-month follow-up, and 30 at 24-month follow-up. At baseline, 119 patients (66.9%) had a QFR ≤0.80, whereas 12 (6.5%) post-PCI, 13 (7.3%) at 6- or 9-month follow-up, and 3 (10.0%) at 24-month follow-up had a QFR ≤0.80. QFR improved from baseline to post-PCI, and decreased from post-PCI up to 24-month follow-up. During follow-up period, 28 patients (11.9%) had target vessel revascularization, of which 21 had analyzable QFR and 16 patients (76.1%) had QFR ≤0.80 at the time of revascularization. Off-line serial QFR assessment demonstrated that around 30% patients did not have functionally significant lesions at baseline and the time with target vessel revascularization. PCI with the Fantom BRS improved functional ischemia with a slight decrease in QFR values over 24 months.

Diagnostic Performance of Angiogram-Derived Fractional Flow Reserve: A Pooled Analysis of 5 Prospective Cohort Studies

ObjectivesThis study sought to assess the diagnostic performance of FFRangio (CathWorks, Kfar Saba, Israel), an angiogram-derived fractional flow reserve (FFR) technology. BackgroundDespite practice guidelines recommendations, the use of coronary physiologic assessment in daily practice remains low for patients undergoing coronary angiography. Angiogram-derived FFR technologies have the potential to promote the integration of physiologic assessment in daily practice. MethodsThe study performed an analysis of pooled patient- and lesion-level data from 5 prospective cohort studies that examined the diagnostic performance of FFRangio compared with the reference standard wire-based FFR. ResultsA total of 700 lesions from 588 patients were analyzed. Mean age was 65 years, 71% were men, and 40% presented with acute coronary syndromes. Mean FFR and FFRangio were 0.81 ± 0.12 and 0.81 ± 0.11, with 31.6% and 31.4% of lesions were in the 0.75 to 0.85 range, respectively. When using a binary cutoff FFR value of 0.80, FFRangio showed a sensitivity of 91%, a specificity of 94%, and a diagnostic accuracy of 93%. The mean difference between FFR and FFRangio was 0.00 ± 0.12. The correlation coefficient between FFR and FFRangio was 0.83 (p < 0.001). The C-statistic for FFRangio was 0.95 (p < 0.001). The accuracy of FFRangio was consistent across all subgroups examined. ConclusionsIn the largest reported cohort examining the performance of angiogram-derived FFR technology, FFRangio showed excellent diagnostic performance, which was robust and consistent across all patient and lesion subgroups. Additional studies are needed allow FFRangio and fulfill its potential expand the implementation of functional assessment of coronary lesions in routine clinical practice.

Diagnostic accuracy of intracoronary optical coherence tomography-derived fractional flow reserve for assessment of coronary stenosis severity.

A novel method for computation of fractional flow reserve (FFR) from optical coherence tomography (OCT) was developed recently. This study aimed to evaluate the diagnostic accuracy of a new OCT-based FFR (OFR) computational approach, using wire-based FFR as the reference standard. Patients who underwent both OCT and FFR prior to intervention were analysed. The lumen of the interrogated vessel and the ostia of the side branches were automatically delineated and used to compute OFR. Bifurcation fractal laws were applied to correct the change in reference lumen size due to the step-down phenomenon. OFR was compared with FFR, both using a cut-off value of 0.80 to define ischaemia. Computational analysis was performed in 125 vessels from 118 patients. Average FFR was 0.80±0.09. Accuracy, sensitivity, specificity, positive predictive value, and negative predictive value for OFR to identify FFR ≤0.80 was 90% (95% CI: 84-95), 87% (95% CI: 77-94), 92% (95% CI: 82-97), 92% (95% CI: 82-97), and 88% (95% CI: 77-95), respectively. The AUC was higher for OFR than minimal lumen area (0.93 [95% CI: 0.87-0.97] versus 0.80 [95% CI: 0.72-0.86], p=0.002). Average OFR analysis time was 55±23 seconds for each OCT pullback. Intra- and inter-observer variability in OFR analysis was 0.00±0.02 and 0.00±0.03, respectively. OFR is a novel and fast method allowing assessment of flow-limiting coronary stenosis without pressure wire and induced hyperaemia. The good diagnostic accuracy and low observer variability bear the potential of improved integration of intracoronary imaging and physiological assessment.

Functional assessment of tandem coronary artery stenosis by intracoronary optical coherence tomography-derived virtual fractional flow reserve: a case series.

BackgroundOptical coherence tomography (OCT)-derived fractional flow reserve (FFR)—which may be calculated using fluid dynamics—demonstrated an excellent correlation with the wire-based FFR. However, the applicability of the OCT-derived FFR in the assessment of tandem lesions is currently unclear.Case summaryWe present two cases of tandem lesions in the mid segment of the left anterior descending (LAD) artery which could have assessed accurately by OCT-derived FFR. The first patient underwent wire-based FFR at the far distal site of LAD, showed a value of 0.66. The OCT-derived FFR was calculated, yielding a value of 0.64. In the absence of stenosis at the proximal lesion, the OCT-derived FFR was calculated as 0.79, which was as same as the wire-based FFR obtained after stenting to the proximal lesion. Thus, additional stenting was performed at the distal lesion. The second patient underwent wire-based FFR at the far distal site of LAD, showed a value of 0.76 which was as same vale as OCT-derived FFR. Considering the absence of stenosis in the proximal lesion, the OCT-derived FFR was estimated as 0.88. After coronary stenting in the proximal lesion, the wire-based FFR yielded a value of 0.90. Therefore, additional intervention to the distal lesion was deferred.DiscussionThe described reports are the first two cases which performed physiological assessment using OCT in tandem lesions. The OCT-derived FFR might be able to estimate the wire-based FFR and the severity of each individual lesion in patients with tandem lesions.