FFR Values Research Articles

Safety and effectiveness of post percutaneous coronary intervention physiological assessment: Retrospective data from the post-revascularization optimization and physiological evaluation of intermediate lesions using fractional flow reserve registry.

BackgroundWhile the importance of invasive physiological assessment (IPA) to choose coronary lesions to be treated is ascertained, its role after PCI is less established. We evaluated feasibility and efficacy of Physiology-guided PCI in the everyday practice in a retrospective registry performed in a single high-volume and “physiology-believer” center.Materials and methodsThe PROPHET-FFR study (NCT05056662) patients undergoing an IPA in 2015–2020 were retrospectively enrolled in three groups: Control group comprising patients for whom PCI was deferred based on a IPA; Angiography-Guided PCI group comprising patients undergoing PCI based on an IPA but without a post-PCI IPA; Physiology-guided PCI group comprising patients undergoing PCI based on an IPA and an IPA after PCI, followed by a physiology-guided optimization, if indicated. Optimal result was defined by an FFR value ≥ 0.90.ResultsA total of 1,322 patients with 1,591 lesions were available for the analysis. 893 patients (67.5%) in Control Group, 249 patients (18.8%) in Angiography-guided PCI Group and 180 patients (13.6%) in Physiology-guided PCI group. In 89 patients a suboptimal functional result was achieved that was optimized in 22 cases leading to a “Final FFR” value of 0.90 ± 0.04 in Angiography-Guided PCI group. Procedural time, costs, and rate of complications were similar. At follow up the rate of MACEs for the Physiology-guided PCI group was similar to the Control Group (7.2% vs. 8.2%, p = 0.765) and significantly lower than the Angiography-guided PCI Group (14.9%, p < 0.001), mainly driven by a reduction in TVRs.Conclusion“Physiology-guided PCI” is a feasible strategy with a favorable impact on mid-term prognosis. Prospective studies using a standardized IPA are warrant to confirm these data.

Study of tribological properties of human buccal epithelium cell membranes using probe microscopy

In this work demostrates a unique method for determining the absolute value of the friction force of a nanoobject on the surface of a cell membrane using atomic force microscopy. The tribological properties of membranes of adult human buccal epithelium cells in the presence of a protective adsorption buffer layer of ~ 100 nm on their surface were studied using atomic force microscopy in the contact scanning mode. Local mapping of the tribological characteristics of the surface was carried out, viz. friction FL = FL(x, y) and adhesion Fadh = Fadh(x, y) forces were measured. Studies of the friction force Ffr on the membrane surface at the nanolevel showed that its value varies discretely with an interval equal to lLF ≈ 100 nm. It was shown that such discreteness is determined by the interval lLF of the action of adhesive forces Fadh and indicates the fractal nature of the functional dependence of the friction force on the coordinate Ffr = Ffr(x). Thus, for nano-objects with dimensions ≤ lLF, the absolute value of Ffr decreases according to a power law with an increase in the size of the object, which contradicts the similar dependence of the friction force for macro-objects in the global approximation.

Optimization of FFR prediction algorithm for gray zone by hemodynamic features with synthetic model and biometric data

BackgroundRecent attempts on adopting artificial intelligence algorithm on coronary diagnosis had limitations on data quantity and quality. While most of previous studies only used vessel image as input data, flow features and biometric features should be also considered. Moreover, the accuracy should be optimized within gray zone as the purpose is to decide stent insertion with estimated fractional flow reserve. ObjectivesThe main purpose of this study is to develop an artificial intelligence-based coronary vascular diagnosis system focused on performance in the gray zone, from CT image extraction to FFR estimation. Three main issues should be considered for an algorithm to be used for pre-screening: algorithm optimization in the gray zone, minimization of labor during image processing, and consideration of flow and biometric features. This paper introduces a full FFR pre-screening system from automatic image extraction to an algorithm for estimating the FFR value. MethodThe main techniques used in this study are an automatic image extraction algorithm, lattice Boltzmann method based computational fluid dynamics analysis of a synthetic model and patient data, and an AI algorithm optimization. For feature extraction, this study focused on an automatic process to reduce manual labor. The algorithm consisted of two steps: the first algorithm calculates flow features from geometrical features, and the second algorithm estimates the FFR value from flow features and patient biometric features. Algorithm selection, outlier elimination, and k-fold selection were included to optimize the algorithm. ConclusionEight types of algorithms including two neural network models and six machine learning models were optimized and tested. The random forest model shows the highest performance before optimization, whereas the multilayer perceptron regressor shows the highest gray zone accuracy after optimization.

Three year clinical outcomes of fractional flow reserve guided coronary revascularization using a monorail pressure sensor microcatheter

Abstract Funding Acknowledgements Type of funding sources: None. Background Fractional flow reserve (FFR) has a Class 1A recommendation for guiding coronary revascularization in stable coronary artery disease. Deferral of revascularization for coronary stenosis of FFR &amp;gt;0.80 has shown favorable long-term outcomes, yet the adoption in real-world practice is limited. To date, there is no study on FFR guided PCI in the Malaysian population. Objective (1) To explore the 3-year clinical outcome of FFR guided coronary revascularization. (2) To compare the clinical outcome of FFR guided deferral of coronary revascularization versus FFR guided revascularization. The primary outcome was a composite of all cause mortality, non fatal myocardial infarction (MI) and ischemia driven target vessel revascularization (TVR) Results Thirty-five patients were lost to follow up leaving 78 patients (95 vessels) for final analysis. The mean age was 59.3 ± 9.4 years old. 69 (88.5%) patients were male, 24 (30.7%) had diabetes mellitus, 58 (74.3%) had dyslipidemia, 61 (78.2%) had hypertension and 45 (57.7%) were smokers. The mean LVEF was 56.7 ± 14.7%. FFR to the LAD artery was performed in 64 (82%) patients. Based on the FFR value of 0.80, 47 (60.2%) patients had FFR guided deferral of coronary revascularization and 31 (39.7%) patients had FFR guided revascularization. At 3 years, 11 (14.1%) patients met the primary outcome, mainly driven by all-cause mortality (11.5%). The primary outcome was met in 14.9% of FFR guided deferral versus 12.9% of FFR guided revascularization (p = 0.828). All-cause mortality was 12.7% in patients with FFR guided deferral compared to 9.7% in patients with FFR guided revascularization at 3 years (p = 0.712). Cox proportional hazards model did not demonstrate any independent predictors associated with the primary outcome or all cause mortality. Conclusion FFR guided deferral of revascularization was safe and had comparable long-term clinical outcomes to FFR guided PCI. To our knowledge, this is the first study on long-term clinical outcome on FFR guided revascularization in Malaysia. Abstract Figure. Kaplan-Meier curve primary end point Abstract Figure. Kaplan-Meier curve all cause mortality

Performance and 12 month outcomes of a wire free fractional flow reserve system for assessment of coronary artery disease, first experience in south east asia

Abstract Funding Acknowledgements Type of funding sources: None. Background Fractional flow reserve (FFR) using an invasive pressure wire has a Class 1A recommendation for guiding coronary revascularization in stable coronary artery disease (CAD). Angiography based ‘wire free’ FFR is an emerging technique which determines the physiological significance of a coronary lesion without requirement of a pressure wire or induction of hyperemia. It also eliminates potential complications associated with introduction of wires into the coronary arteries. Objective To assess the 12-month clinical outcomes of PCI deferral, guided by an angiography based fractional flow reserve (CAFFR) system. The primary end point was a composite of death from any cause, myocardial infarction (MI) or target vessel revascularization (TVR) Methods This was a prospective, single center study involving 69 patients (93 vessels) with angiographic stenosis of 30%-90%. Patients with CAFFR of &amp;lt;0.80 or poor image quality were excluded leaving 29 patients (31 vessels) for analysis. All recruited patients had a CAFFR &amp;gt;0.80 and thus, PCI deferral. Wired FFR was done for comparison on 14 patients (48%) at the operator’s discretion. Results The mean age was 59 ± 12.6 years old. Majority of patients (83%) were male. 12 (42%) patients were diabetic, 18 (62%) were hypertensive, 17 (59%) had dyslipidemia and 18 (62%) had a smoking history. The mean LVEF was 52+/-11.4%. 72% of the patients had a recent acute coronary syndrome. We assessed the LAD artery in 15 (52%) vessels. The mean CAFFR and FFR was 0.87 ± 0.04 and 0.89 ± 0.05 respectively. The values showed agreement with each other with no statistically significant proportional bias on the Bland Altman plot (linear regression t test: t=-1.19, p = 0.257). CAFFR values &amp;gt;0.80 showed 100% correspondence to negative FFR values (&amp;gt;0.80). There were zero procedural complications from CAFFR measurement. At 12 months, all 29 patients were alive. Only 1 patient (3.4%) met the primary end point (TVR for angina). 89.6% (26) patients remained in CCS class 1 on follow up. Conclusion CAFFR shows good agreement with wired FFR. The 12-month outcome data shows that CAFFR guided PCI deferral is safe and comparable to the gold standard of wired FFR guided PCI deferral. Further analysis with a larger patient pool and longer follow-up is warranted. Abstract Figure. Bland-Altman plot of FFR and CAFFR

Single center experience in the treatment of hemodynamically significant diffuse coronary artery disease of the left anterior descending

IntroductionTo date there are no recommendations on how to treat patients with an FFR positive but diffusely diseased left anterior descending coronary artery (LAD). Benefit of coronary artery bypass grafting (CABG) or percutaneous coronary intervention (PCI) is not so evident due to doubts regarding longevity and patency. MethodsThis retrospective single-center study assessed clinical outcomes in patients presenting with symptomatic single vessel coronary artery disease of a diffusely diseased, hemodynamically significant LAD treated by coronary artery bypass grafting (CABG) or optimal medical therapy (OMT) between 2015 and 2020. Primary outcome of this study was the composite endpoint of all-cause mortality, myocardial infarction and repeat revascularization during 2-year follow-up. Secondary endpoints consisted of the individual components of the primary endpoint. Change in angina severity grade based on the Canadian Cardiovascular Society (CCS) class between baseline and 2-year follow-up was assessed. ResultsFifty-nine patients were included of which 25 patients underwent CABG and 34 patients were treated by OMT. There was a statistically significant difference in FFR value at baseline between the treatment groups (CABG 0.70 ± 0.04; OMT 0.75 ± 0.04; p < 0.001). After 2-year follow-up, there were no statistically significant differences with regard to the primary endpoint (CABG 16% (n = 4); OMT 17.6% (n = 6); p = 1.00) and secondary endpoints between the groups over 2-year follow-up. ConclusionIn patients with hemodynamically significant diffuse single vessel coronary artery disease of the left anterior descending, there was no difference between OMT and CABG in terms of mortality, myocardial infarction, revascularization and symptom reduction after two years of follow-up.

Effect of Coronary Calcification Severity on Measurements and Diagnostic Performance of CT-FFR With Computational Fluid Dynamics: Results From CT-FFR CHINA Trial.

Aims: To explore the effect of coronary calcification severity on the measurements and diagnostic performance of computed tomography-derived fractional flow reserve (FFR; CT-FFR).Methods: This study included 305 patients (348 target vessels) with evaluable coronary calcification (CAC) scores from CT-FFR CHINA clinical trial. The enrolled patients all received coronary CT angiography (CCTA), CT-FFR, and invasive FFR examinations within 7 days. On both per-patient and per-vessel levels, the measured values, accuracy, and diagnostic performance of CT-FFR in identifying hemodynamically significant lesions were analyzed in all CAC score groups (CAC = 0, > 0 to <100, ≥ 100 to <400, and ≥ 400), with FFR as reference standard.Results: In total, the sensitivity, specificity, positive predictive value, negative predictive value, accuracy, and area under receiver operating characteristics curve (AUC) of CT-FFR were 85.8, 88.7, 86.9, 87.8, 87.1%, 0.90 on a per-patient level and 88.3, 89.3, 89.5, 88.2, 88.9%, 0.88 on a per-vessel level, respectively. Absolute difference of CT-FFR and FFR values tended to elevate with increased CAC scores (CAC = 0: 0.09 ± 0.10; CAC > 0 to <100: 0.06 ± 0.06; CAC ≥ 100 to <400: 0.09 ± 0.10; CAC ≥ 400: 0.11 ± 0.13; p = 0.246). However, no statistically significant difference was found in patient-based and vessel-based diagnostic performance of CT-FFR among all CAC score groups.Conclusion: This prospective multicenter trial supported CT-FFR as a viable tool in assessing coronary calcified lesions. Although large deviation of CT-FFR has a tendency to correlate with severe calcification, coronary calcification has no significant influence on CT-FFR diagnostic performance using the widely-recognized cut-off value of 0.8.

389 Microvascular dysfunction in patients with Type II diabetes mellitus: invasive assessment of absolute coronary blood flow and microvascular resistance reserve

Abstract Aims Coronary microvascular dysfunction (CMD) is an early feature of diabetic cardiomyopathy, which usually precedes the onset of diastolic and systolic dysfunction. Continuous intracoronary thermodilution allows an accurate and reproducible assessment of absolute coronary blood flow and microvascular resistance thus allowing the evaluation of coronary flow reserve (CFR) and Microvascular Resistance Reserve (MRR), a novel index specific for microvascular function, which is independent from the myocardial mass. In the present study we compared absolute coronary flow and resistance, CFR and MRR assessed by continuous intracoronary thermodilution in diabetic vs. non-diabetic patients. Left atrial reservoir strain (LASr), an early marker of diastolic dysfunction was compared between the two groups. Methods In this observational retrospective study, 108 patients with suspected angina and non-obstructive coronary artery disease (NOCAD) consecutively undergoing elective coronary angiography (CAG) from September 2018 to June 2021 were enrolled. The invasive functional assessment of microvascular function was performed in the left anterior descending artery (LAD) with intracoronary continuous thermodilution. Patients were classified according to the presence of DM. Absolute resting and hyperaemic coronary blood flow (in mL/min) and resistance (in WU) were compared between the two cohorts. FFR was measured to assess coronary epicardial lesions, while CFR and MRR were calculated to assess microvascular function. LAS, assessed by speckle tracking echocardiography, was used to detect early myocardial structural changes potentially associated with microvascular dysfunction. Results The median FFR value was 0.83 (0.79–0.87) without any significant difference between the two groups. Absolute resting and hyperaemic flow in the left anterior descending coronary were similar between diabetic and non-diabetic patients. Similarly, resting and hyperaemic resistances did not change significantly between the two groups. In the DM cohort the CFR and MRR were significantly lower compared to the control group [CFR = 2.38 ± 0.61 and 2.88 ± 0.82; MRR = 2.79 ± 0.87 and 3.48 ± 1.02 for diabetic and non-diabetic patients respectively, (P &amp;lt; 0.05 for both)]. Likewise, diabetic patients had a significantly lower reservoir, contractile and conductive LAS (all P &amp;lt; 0.05). Conclusions Compared with non-diabetic patients, CFR and MRR were lower in patients with DM and non-obstructive epicardial coronary arteries, while both resting and hyperaemic coronary flow and resistance were similar. LASr was lower in diabetic patients, confirming the presence of a subclinical diastolic dysfunction associated to the microcirculatory impairment. Continuous intracoronary thermodilution-derived indexes provide a reliable and operator-independent assessment of coronary macro- and microvasculature and might potentially facilitate widespread clinical adoption of invasive physiologic assessment of suspected microvascular disease.

Abstract 9140: Validity of Coronary Angiography-Based Physiology in Clinical Practice

Introduction: The invasive physiological assessment of the severity of coronary obstruction is performed by hyperemic (FFR) and non-hyperemic (iFR) indices. However, the need to insert an intracoronary pressure guidewire are factors that limit its use. Quantitative flow ratio (QFR) is a method that infers the value of FFR, eliminating the use of a pressure wire and coronary hyperemia. Objectives: Evaluate the diagnostic accuracy of the QFR, diameter stenosis percentual (DS%) and area stenosis percentual (AS%) in comparison with the FFR, for identification of significant obstructive coronary lesions (FFR ≤ 0.80) and the feasibility to assess QFR in cohort of patients without dedicated angiographic acquisition. Methods: Consecutive patients with moderate obstructive lesions in coronary angiography that had previous FFR measurement were evaluated. Validation of QFR was assessed by accuracy, area under the curve (AUC), sensitivity, specificity, correlation coefficient and Bland-Altman plot, using FFR as reference method. Results: Out of 102 patients and 143 arteries assessed by the FFR, only 69 (67%) patients and 75 (52%) arteries were possible to be calculated by QFR. The accuracy of the QFR to detect an FFR ≤ 0.80 was 84.0% (95% CI: 75.6% to 92.4%), with a sensitivity of 67.9% (95% CI: 47.6% to 84.1%) and specificity of 93.6% (95% CI: 82.5% to 98.7%). The correlation and agreement between FFR and QFR were r = 0.54, p &lt; 0.01 and mean difference = -0.02 ± 0.09; p = 0.0874, respectively. The AUC to QFR, DS% and AS% comparison are represented in the attached figure. Conclusions: QFR demonstrated good accuracy and agreement, compared to the FFR, with moderate correlation in an unselected population of clinical practice. QFR and DS% demonstrated AUC greater than AS%. However, the high rate of exclusion in offline evaluations of angiograms recorded without dedicated acquisition protocol considerably limits the use of this tool in clinical practice.

A phantom and in vivo simulation of coronary flow to calculate fractional flow reserve using a mesh-free model.

Moving particle semi-implicit (MPS) method is a mesh-free method to perform computational fluid dynamics (CFD). The purpose of this study was to calculate the simulated fractional flow reserve (sFFR) using a coronary stenosis model, and to validate the MPS-derived sFFR against invasive FFR using clinical coronary CT data. Coronary flow simulation included 21 stenosis models with stenosis ranging 30-70%. Patient coronary analysis was performed in 76 consecutive patients (100 vessels) who underwent coronary CT angiography and subsequent invasive FFR between November 2016 and March 2020. Accuracy of sFFR and CT angiography for diagnosis of invasive FFR ≤ 0.80 was compared. Quantitative morphological stenosis data of CT angiography were also obtained. Area stenosis showed a good correlation to sFFR (R2 = 0.996, p < 0.001) in coronary stenosis models. In the patient study, the mean FFR value was 0.82 ± 0.10, and 37 out of 100 vessels showed FFR ≤ 0.80. FFR and sFFR values showed a good correlation (R2 = 0.59, p < 0.001) with a slight underestimation of sFFR as compared with FFR (mean difference - 0.015 ± 0.096, p = 0.12). The sensitivity, specificity, positive predictive value, and negative predictive value of sFFR to predict FFR ≤ 0.80 was 86%, 89%, 82%, 92%, respectively. The accuracy to predict FFR ≤ 0.80 using sFFR was greater than using diameter stenosis and minimum lumen area (88% vs. 74%, p = 0.008). CFD using the MPS method showed feasible results validated against invasive FFR. The accuracy to predict significant stenosis was higher than morphological stenosis.

TCT-193 The Correlation and Relative Prognostic Value of FFR and Pd/Pa of Nonculprit Lesions in STEMI

TCT-193 The Correlation and Relative Prognostic Value of FFR and Pd/Pa of Nonculprit Lesions in STEMI

Microvascular Dysfunction in Patients With Type II Diabetes Mellitus: Invasive Assessment of Absolute Coronary Blood Flow and Microvascular Resistance Reserve.

Background: Coronary microvascular dysfunction (CMD) is an early feature of diabetic cardiomyopathy, which usually precedes the onset of diastolic and systolic dysfunction. Continuous intracoronary thermodilution allows an accurate and reproducible assessment of absolute coronary blood flow and microvascular resistance thus allowing the evaluation of coronary flow reserve (CFR) and Microvascular Resistance Reserve (MRR), a novel index specific for microvascular function, which is independent from the myocardial mass. In the present study we compared absolute coronary flow and resistance, CFR and MRR assessed by continuous intracoronary thermodilution in diabetic vs. non-diabetic patients. Left atrial reservoir strain (LASr), an early marker of diastolic dysfunction was compared between the two groups.Methods: In this observational retrospective study, 108 patients with suspected angina and non-obstructive coronary artery disease (NOCAD) consecutively undergoing elective coronary angiography (CAG) from September 2018 to June 2021 were enrolled. The invasive functional assessment of microvascular function was performed in the left anterior descending artery (LAD) with intracoronary continuous thermodilution. Patients were classified according to the presence of DM. Absolute resting and hyperemic coronary blood flow (in mL/min) and resistance (in WU) were compared between the two cohorts. FFR was measured to assess coronary epicardial lesions, while CFR and MRR were calculated to assess microvascular function. LAS, assessed by speckle tracking echocardiography, was used to detect early myocardial structural changes potentially associated with microvascular dysfunction.Results: The median FFR value was 0.83 [0.79–0.87] without any significant difference between the two groups. Absolute resting and hyperemic flow in the left anterior descending coronary were similar between diabetic and non-diabetic patients. Similarly, resting and hyperemic resistances did not change significantly between the two groups. In the DM cohort the CFR and MRR were significantly lower compared to the control group (CFR = 2.38 ± 0.61 and 2.88 ± 0.82; MRR = 2.79 ± 0.87 and 3.48 ± 1.02 for diabetic and non-diabetic patients respectively, [p < 0.05 for both]). Likewise, diabetic patients had a significantly lower reservoir, contractile and conductive LAS (all p < 0.05).Conclusions: Compared with non-diabetic patients, CFR and MRR were lower in patients with DM and non-obstructive epicardial coronary arteries, while both resting and hyperemic coronary flow and resistance were similar. LASr was lower in diabetic patients, confirming the presence of a subclinical diastolic dysfunction associated to the microcirculatory impairment. Continuous intracoronary thermodilution-derived indexes provide a reliable and operator-independent assessment of coronary macro- and microvasculature and might potentially facilitate widespread clinical adoption of invasive physiologic assessment of suspected microvascular disease.

Abnormal fractional flow reserve and non-hyperaemic pressure ratios in patients with severe aortic stenosis and non-obstructive coronary artery disease

Abstract Background Fractional flow reserve (FFR) and non-hyperaemic pressure ratios (NHPRs) are well-validated tools that assess the physiological significance of coronary artery disease (CAD). Low coronary lumen to myocardial mass (V/M) ratio on CT is associated with lower FFR/NHPRs and predisposes towards ischaemia in CAD. Whilst CAD and aortic stenosis (AS) frequently co-exist, patients report angina despite obstructive disease. Purpose We therefore sought to study the interrelationship between V/M and invasive pressure indices in patients with severe AS. Methods 35 patients with severe AS were prospectively recruited as part of CAST-FFR study. Patients underwent CT coronary angiography and invasive pressure-wire assessment. All pressure-indices were assessed in the left anterior descending artery (LAD). Data was extracted to calculate FFR, iFR, diastolic pressure ratios (DPR and dPR) and Diastolic Hyperaemia-free Ratio (DFR). Patient-specific V/M were extracted off-site by independent core lab. Results Mean age was 75±7.5 years, median V/M ratio was 20.7 and mean aortic gradient and DI were 44.3±11.6mmHg and 0.23±0.4 respectively. 79% of patients had CADRADs score of &amp;lt;2. There were moderate positive correlations between FFR/NHPRs and V/M, including FFR (r=0.60), PdPa (r=0.48), iFR (r=0.59), DPR (r=0.59), dPR (r=0.63), DFR (r=0.67), (all p&amp;lt;0.005). In patients with positive pressure assessments, 69% (FFR), 71% (iFR), 70% (DPR) and 65% (DFR) had CADRADs score &amp;lt;2. In severe AS, lower V/M was associated with lower pressure-indices (FFR 0.75 vs 0.86, iFR 0.79 vs 0.92, DFR 0.80 vs 0.91, all p&amp;lt;0.005), leading to high rates of positive physiologic assessment (FFR 88%, PdPa 72%, iFR 67%, DPR 78%, DFR 74%). Conclusion Patients with severe AS exhibit high rates of abnormal FFR and NHPR values, despite having no obstructive CAD. Their propensity for having abnormal physiological results is, in part, influenced by coronary volume to mass ratio. These results are important for clinicians considering using invasive physiological tools to guide revascularisation decisions in patients with severe AS. Funding Acknowledgement Type of funding sources: Public Institution(s). Main funding source(s): Monash University, Cardiac Society of Australia and New Zealand Correlation between NHPR/FFR and VMInvasive pressure indices and VM

Validation of Coronary Angiography-Derived Vessel Fractional Flow Reserve in Heart Transplant Patients with Suspected Graft Vasculopathy.

Cardiac transplant-related vasculopathy remains a leading cause of morbidity and mortality in heart transplant (HTx) recipients. Recently, coronary angiography-derived vessel fractional flow reserve (vFFR) has emerged as a new diagnostic computational tool to functionally evaluate the severity of coronary artery disease. Although vFFR estimates have been shown to perform well against invasive FFR in atherosclerotic coronary artery disease, data on the use of vFFR in heart transplant recipients suffering from cardiac transplant-related arteriopathy are lacking. The aim of the presented study was to validate coronary angiography-derived vessel fractional flow reserve to calculate fractional flow reserve in HTx patients with and without cardiac transplant-related vasculopathy. A prospective, single center study of HTx patients referred for annual check-up, undergoing surveillance coronarography was conducted. Invasive FFR was measured using a motorized device at the speed of 1.0 mm/s in all three major coronary arteries. Angiography-derived pullback FFR was derived from the angiogram and compared with invasive FFR pullback curve. Overall, 18,059 FFR values were extracted from the FFR pullback curves from 23 HTx patients. The mean age was 59.3 ± 9.7 years, the mean time after transplantation was 5.24 years [IQR 1.20, 11.25]. A total of 39 vessels from 23 patients (24 LAD, 11 LCX, 4 RCA) were analyzed. Mean distal vFFR was 0.87 ± 0.14 whereas invasive distal FFR was 0.88 ± 0.17. An excellent correlation was found between invasive distal FFR and vFFR (r = 0.92; p < 0.001). The correlation of the pullback tracing was high, with a correlation coefficient between vFFR and invasive FFR pullback values of 0.72 (95% CI 0.71 to 0.73, p < 0.001). The mean difference between vFFR and invasive FFR pullback values was −0.01 with 0.06 of SD (limits of agreements −0.12 to 0.13). In HTx patients, coronary angiography-derived FFR correlates excellently with invasively measured wire-derived FFR. Therefore, angiography derived FFR could be used as a novel diagnostic tool to quantify the functional severity of graft vasculopathy.

Dobutamine stress echocardiography in patients with moderate coronary artery disease detected by coronary computed tomography angiography could reduce the rate of unnecessary coronary angiography

Aims To test the hypothesis that dobutamine stress echocardiography (DSE) reduces the rate of unnecessary invasive coronary angiography (CA) in patients with chronic stable coronary artery disease (CAD) and moderate to severe stenosis detected by coronary computed tomography angiography (CCTA). Methods This study included 49 consecutive, symptomatic CAD patients with coronary lesions greater than 50% detected by CCTA who underwent all DSE and a CA with pressure wire evaluation and FFR measurement. The DSE operators was aware of the CCTA results, but invasive physicians were blinded to DSE results. The primary endpoint was the negative predictive value of a CCTA followed by a DSE test for detecting significant coronary artery disease (CAD). This was defined by the presence of significant coronary lesions (>90% stenosis) or moderate coronary lesions (50–90%) with abnormal FFR value of less than 0.80 evaluated by invasive angiogram (CA). Secondary endpoints included major adverse cardiovascular events (MACEs). Results In patients with abnormal CCTA followed by CA, 33 patients (67.34%) had non-significant CAD lesions. In patients with both abnormal CCTA and DSE only 6 patients (12.24%) presented non-significant CAD. The negative predictive value of a CCTA followed by a DSE was significantly increased to 92.5%, when compared with CCTA alone. Thus DSE on top of abnormal CCTA could reduce unnecessary CA by 5.5 fold. During follow-up (mean 38.75 ± 12.25 months) 1 (2.1%) patient had a cardiac sudden death, 3 (6.12%) patients had an unplanned myocardial revascularization and 1 (2.1%) patient had a stroke, none of which occurred in patients with normal DSE. No patients experienced a myocardial infarction or needed un unplanned surgical revascularization. Conclusions The addition of DSE in case of abnormal CCTA increases significantly the negative predictive value for detecting significant CAD in need for revascularisation and thus reduces markedly the number of unnecessary CA. This diagnostic strategy has a higher diagnostic accuracy and negative predictive value to the opposite approach where an abnormal CCTA mandates a CA without additional functional testing.

Diagnostic accuracy of coronary computed tomography angiography-derived fractional flow reserve

BackgroundFractional flow reserve (FFR) is a widely used gold standard to evaluate ischemia-causing lesions. A new method of non-invasive approach, termed as AccuFFRct, for calculating FFR based on coronary computed tomography angiography (CCTA) and computational fluid dynamics (CFD) has been proposed. However, its diagnostic accuracy has not been validated.ObjectivesThis study sought to present a novel approach for non-invasive computation of FFR and evaluate its diagnostic performance in patients with coronary stenosis.MethodsA total of 54 consecutive patients with 78 vessels from a single center who underwent CCTA and invasive FFR measurement were retrospectively analyzed. The CT-derived FFR values were computed using a novel CFD-based model (AccuFFRct, ArteryFlow Technology Co., Ltd., Hangzhou, China). Diagnostic performance of AccuFFRct and CCTA in detecting hemodynamically significant coronary artery disease (CAD) was evaluated using the invasive FFR as a reference standard.ResultsDiagnostic accuracy, sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) for AccuFFRct in detecting FFR ≤ 0.8 on per-patient basis were 90.7, 89.5, 91.4, 85.0 and 94.1%, respectively, while those of CCTA were 38.9, 100.0, 5.71, 36.5 and 100.0%, respectively. The correlation between AccuFFRct and FFR was good (r = 0.76 and r = 0.65 on per-patient and per-vessel basis, respectively, both p < 0.0001). Area under the curve (AUC) values of AccuFFRct for identifying ischemia per-patient and per-vessel basis were 0.945 and 0.925, respectively. There was much higher accuracy, specificity and AUC for AccuFFRct compared with CCTA.ConclusionsAccuFFRct computed from CCTA images alone demonstrated high diagnostic performance for detecting lesion-specific ischemia, it showed superior diagnostic power than CCTA and eliminated the risk of invasive tests, which could be an accurate and time-efficient computational tool for diagnosing ischemia and assisting clinical decision-making.

Evaluation of the Fractional Flow Reserve by Computer Tomography Data: Comparison of the Calculated Parameters with the Results of Invasive Measurements.

Aim To create a three-dimensional mathematical model of coronary flow in patients with ischemic heart disease based on findings of computed tomography angiography (CTA) with subsequent calculation of the fractional flow reserve (FFRCTA) and comparison of estimated FFRCTA with FFR reference values measured by coronary angiography (CAG).Material and methods The study included 10 patients with borderline stenosis (50-75 %) as determined by CTA performed with a 640‑slice CT-scanner. Based on CTA findings, three-dimensional mathematical models were constructed for further calculation of FFRCTA. Later, an invasive measurement of FFR (FFRINV) was performed for all patients. FFR values &lt;0.8 indicated the hemodynamic significance of stenosis.Results FFRCTA and FFRINV values differed insignificantly in most cases (n=9) and exceeded 5% in only one case. The regression analysis showed a close correlation between estimated and invasively measured FFR values.Conclusion Preliminary results showed a good consistency of calculated and measured FFR values. Therefore, further development of the method for mathematical modeling of three-dimensional blood flow by CTA findings is promising. Noninvasive evaluation of FFR is particularly relevant for analysis of hemodynamic significance of borderline (50-75 %) coronary stenoses.

The diagnostic performance of on-site workstation-based computed tomography-derived fractional flow reserve. Comparison with myocardium perfusion imaging.

To compare the diagnostic performance of on-site workstation-based computed tomography-derived fractional flow reserve (CT-FFR)Few data of CT-FFR were reported regarding the diagnostic performance for detecting hemodynamically significant coronary artery disease (CAD). This retrospective single-center analysis included 132 vessels in 77 patients who underwent CT angiography, myocardial perfusion imaging (MPI), and invasive FFR. The correlation coefficient between CT-FFR and invasive FFR and optimal cut-off value for CT-FFR to identify invasive FFR ≤ 0.8 were evaluated. The diagnostic accuracies of CT- FFR, and MPI were evaluated using an area under the receiver-operating characteristic curve (AUC) with invasive FFR as a reference standard. Diagnostic performance of CT-FFR was also evaluated concerning lesion characteristics, including intermediate lesions, left main lesions, tandem lesions, and/or diffuse lesions, and coronary calcium (Agatston score over 400). The Receiver Operating Characteristic curve analysis showed that the optimal cut-off value of CT-FFR for detecting invasive FFR ≤ 0.80 was 0.80 [AUC = 0.83, 95%CI: 0.76-0.90). Diagnostic sensitivity, specificity, positive and negative predictive value, and accuracy of CT-FFR when compared with those of MPI regarding per-patient analysis were 93% vs. 63%, 48% vs. 61%, 81% vs. 79%, 73% vs. 41%, and 79% vs. 62%, respectively, and for per-vessel analysis were 89% vs. 24%, 66% vs. 82%, 75% vs. 61%, 83% vs. 48%, and 78% vs. 51%, respectively. The AUC of the CT-FFR was significantly higher than MPI (0.83 vs. 0.57, p < 0.0001) regarding the per-vessel analysis. No differences in the diagnostic performance of CT-FFR were noted in the presence of intermediate lesions, left main lesions, tandem lesions, and/or diffuse lesions, and severe coronary calcium. On-site CT-FFR delivered a higher diagnostic performance than MPI for detecting CAD with invasive FFR ≤ 0.8, indicating the potential of CT-FFR as the gatekeeper of invasive coronary angiogram as well as percutaneous coronary intervention.

A prospective multicenter validation study for a novel angiography-derived physiological assessment software: Rationale and design of the radiographic imaging validation and evaluation for Angio-iFR (ReVEAL iFR) study

Angiography-derived physiological assessment of coronary lesions has emerged as an alternative to wire-based assessment aiming at less-invasiveness and shorter procedural time as well as cost effectiveness in physiology-guided decision making. However, current available image-derived physiology software have limitations including the requirement of multiple projections and are time consuming. METHODS/DESIGN: The ReVEAL iFR (Radiographic imaging Validation and EvALuation for Angio-iFR) trial is a multicenter, multicontinental, validation study which aims to validate the diagnostic accuracy of the Angio-iFR medical software device (Philips, San Diego, US) in patients undergoing angiography for Chronic Coronary Syndrome (CCS). The Angio-iFR will enable operators to predict both the iFR and FFR value within a few seconds from a single projection of cine angiography by using a lumped parameter fluid dynamics model. Approximately 440 patients with at least one de-novo 40% to 90% stenosis by visual angiographic assessment will be enrolled in the study. The primary endpoint is the sensitivity and specificity of the iFR and FFR for a given lesion compared to the corresponding invasive measures. The enrollment started in August 2019, and was completed in March 2021. SUMMARY: The Angio-iFR system has the potential of simplifying physiological evaluation of coronary stenosis compared with available systems, providing estimates of both FFR and iFR. The ReVEAL iFR study will investigate the predictive performance of the novel Angio-iFR software in CCS patients. Ultimately, based on its unique characteristics, the Angio-iFR system may contribute to improve adoption of functional coronary assessment and the workflow in the catheter laboratory.

Future culprit detection based on angiography‐derived FFR

We sought to characterize the hemodynamic impact of mild coronary artery disease (CAD) using quantitative flow ratio (QFR, an angiography-derived fractional flow reserve [FFR]) in a population of patients with only non-significant CAD at baseline that subsequently experienced a myocardial infarction (MI). The discriminatory value of FFR in patients with mild CAD remains imperfect. We retrospectively included patients who underwent invasive coronary angiography for an MI, in whom another angiogram had been performed within the previous 5 years. Three-dimensional quantitative coronary angiography, QFR, and lesion length analysis were conducted on lesions responsible for the MI (future culprit lesions, [FCL]) as well as on control lesions (non-culprit lesions, [NCL]). Eighty-three FCL and 117 NCL were analyzed in 83 patients: FCL were more severe (median % diameter of stenosis [DS] 39.1% [29.8; 45.7] vs. 29.8% [25.0; 37.2], p < .001), had lower QFR values (0.94 [0.86; 0.98] vs. 0.98 [0.96; 1.00], p < .001) and tended to be longer (15.2 mm [10.0; 27.3] vs. 12.7 mm [9.3; 22.4], p = .070) than NCL. In lesions with an interval < 2 years between baseline angiography and MI, the difference in QFR was more pronounced compared to the lesions with a longer interval (FCL: 0.92 [0.85; 0.97] vs. NCL: 0.98 [0.94; 1.00], p < .001 and FCL: 0.96 [0.88; 1.00] vs. NCL: 0.98 [0.96;1.00], p = .006 respectively) CONCLUSION: Mild coronary stenoses that are subsequently responsible for an MI (FCL) exhibit a higher DS and lower QFR years before the event. Furthermore, FCL with a lower QFR at baseline appear to lead earlier to MI.