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About 50% of patients diagnosed with ST-segment elevation myocardial infarction have multivessel disease on coronary angiography. Recent evidence has shown that a staged percutaneous coronary intervention (PCI) strategy of non-culprit lesions, achieving complete revascularization, significantly reduces the rate of recurrent cardiovascular events compared with a PCI strategy limited to culprit lesion. Although functional evaluation of intermediate coronary stenoses by functional flow reserve (FFR) or instantaneous wave-free ratio (iFR) is widely used to detect residual myocardial ischaemia, the reliability of the study of non-culprit lesions in the acute phase of heart attack is controversial. On the other hand, the excess of new events in patients with acute coronary syndrome in whom PCI was deferred on the basis of FFR/iFR compared to patients with stable CAD could be due to both an inadequate functional evaluation and an intrinsic higher risk, related to the presence of untreated vulnerable plaques. In this context, intra-coronary imaging has shown that the presence of vulnerability features in non-culprit plaques is associated with an increased rate of ischaemic recurrence.

Introduction The aim in the diagnostic work-up of patients with an anomalous aortic origin of coronary arteries (AAOCA) is to determine whether the course of the coronary artery is benign or malignant. In patients with AAOCA with an interarterial course the guidelines on diagnostics are concise. Recommended CT-scan imaging does not evaluate stress-induced functional consequences like external compression by the pulmonary artery as the scan is performed in a resting state. Non-invasive ischemia detection techniques often lack sufficient sensitivity. To improve functional stratification, exploration of new diagnostic modalities in the diagnostic workup of AAOCA is mandatory. Purpose The purpose is to explore the potential role of intravascular ultrasound (IVUS) in the diagnostic workup of patients with AAOCA. Methods Nine patients with an anomalous right coronary artery with an interarterial course were analyzed. A cardiologist evaluated the complaints. Anatomical features of the AAOCA were assessed with CT-scan imaging. Further analyses included ischemia detection and coronary angiography. To assess stress-induced ischemia IVUS and invasive measurements – fractional flow reserve (FFR) and instantaneous wave-free ratio (iFR) – were performed at rest and during adrenaline-induced stress. A slit-like orifice was classified as a width/length (W/L) ratio of ≤0.50, an oval orifice as 0.51–0.9 and a round orifice as >0.91. Results Potential cardiac complaints were present in seven patients. In 8 (89%) patients CT-images showed an acute angle, in 8 (89%) proximal narrowing and an aortic take-off above the pulmonary valve in 4 (44%). In 7 (78%) patients a slit-like orifice and in two (22%) an oval orifice were observed (table 1). IVUS at rest showed a slit-like orifice in one patient classified as an oval orifice on the CT-images and vice versa in another patient (table 2). The patients classified as an oval orifice with IVUS showed no external compression during adrenaline-induced stress. In 4 (57%) out of 7 patients with an slit-like orifice on IVUS, the width remained unchanged or increased during adrenaline infusion. In 2 patients the width decreased slightly, however, these patients were asymptomatic and no ischemia was detected. In 1 (14%) patient the width remained 1.4mmm and the length increased from 3.2mm to 4.7mm. In this case the vessel ostium was fully engaged with the IVUS catheter, hence, the width could not decrease during adrenaline infusion. This was regarded as external compression. In addition, in this patient ischemia was detected. Conclusion(s) In two (22%) out of 9 patients IVUS gave a better insight of the shape of the orifice than CT. Additionally, the anatomic and functional-dynamic components of compression could be defined with adrenaline-induced stress. Therefore, IVUS can contribute to a better understanding of the functional consequences of the anatomical features and of potential stress-induced external compression. Funding Acknowledgement Type of funding sources: None. Table 1Table 2

Background Single coronary artery (SCA) is a rare congenital anomaly where blood to the heart is supplied through a common trunk. Identifying these abnormalities is important because some variants can compromise myocardial blood flow and increase risk of sudden cardiac death. Case summary We present five patients with varying Lipton Group I and Group II SCA subtypes, corroborated on multi-imaging modalities and evaluated with comprehensive non-invasive as well as invasive testing. Their clinical presentations also vary from a spectrum of asymptomatic finding to angina equivalent. The decision for definitive surgical intervention involving unroofing of the involved vessel depends largely on symptoms and evidence of myocardial ischaemia. Discussion While SCA findings are often incidental and benign, understanding the origin, branching pattern, and course of the anomalous artery has implications in prognosis and treatment. This usually involves a combination of anatomic assessment with imaging such as coronary Computed Tomography Angiography (CTA), Magnetic Resonance Angiography (MRA), and/or coronary angiography as well as functional assessment with invasive testing using tools like instantaneous wave-free ratio and intravascular ultrasound both at rest and with stress. Individualized treatment plans can then be made through a multidisciplinary approach involving adult congenital heart disease specialists and congenital cardiothoracic surgeons.

Background Instantaneous Wave-Free Ratio (iFR) allows for the assessment of the haemodynamic effects of epicardial coronary stenoses without the need for hyperaemia; iFR is currently recommended as a means to evaluate myocardial ischaemia. Purpose To assess the diagnostic accuracy of iFR with respect to the identification of coronary epicardial stenoses causing ischemia. Therefore, we combined anatomical (% stenosis at invasive coronary angiography, ICA) and functional (non-invasive imaging stress test, NIST) information to obtain a “gold standard” for the identification of stenoses causing ischaemia. Methods We enrolled 71 patients (52 male, 19 female; age mean 68.4±8.1 years) with chronic coronary syndrome or low-risk acute coronary syndrome without ST segment elevation who had at least a NIST and who had at least one vessel with a 50%-85% stenosis at ICA. iFR was measured in all coronary arteries with stenosis >50% and categorised according to the 0.89 threshold for ischaemia. Results iFR was assessed in 122 vessels. In a per-vessel analysis, in 56.7% ischaemia was present both at iFR and NIST, in 21.3% ischaemia was absent in both, while in 23.0% ischaemia was found at NIST but not confirmed by iFR. The overall accuracy of iFR with respect to NIST was 90.1%. However, when considering as the “gold standard” for coronary disease causing ischaemia the contemporary presence of an epicardial stenosis >70% at ICA and a positive NIST, the diagnostic accuracy of iFR greatly improved. The sensibility, specificity, PPV, NPV and accuracy were 96.5%, 75.0%, 73.3%, 96.7% and 84.4%, respectively. In case of discordance between NIST and iFR, revascularization was based on iFR. At a mean follow-up of 23±18 months, the composite endpoint of MACE (major adverse cardiac events, defined as the composite of all-cause death, nonfatal MI and unplanned coronary revascularization) occurred in 16.4%, while death/MI occurred in 11.9%. Stratification according to the per-patient concordance between iFR and NIST showed no significant differences in rates of MACE (p=0.50) and death/MI (p=0.20). Stratification based on iFR showed a higher death/MI rate in iFR-positive patients (11.9% vs. 0%, p=0.047) and a trend to higher MACE rate (11.9% vs. 4.47% p=0.14), Conclusions The diagnostic accuracy of iFR is low when compared with NIST as the reference for myocardial ischaemia, but it is very high when compared with the combined presence of epicardial stenosis and positive NIST. Therefore, iFR can accurately guide the decision to treat or defer revascularization of intermediate coronary stenoses, being most useful in patients with multivessel CAD and when non-invasive functional data are lacking or discordant with anatomy. Funding Acknowledgement Type of funding source: None

Background Reliable coronary physiology assessment with pressure derived indexes in patients with aortic stenosis (AS) rises problems due to its complex nature. Recent data suggest that fractional flow reserve (FFR) may underestimate intermediate coronary stenosis in a presence of AS whereas instantaneous wave-free ratio (iFR) values may remain similar after treatment of AS. Furthermore, both indices has not been validated yet in AS. Aim We aimed to find a thresholds for coronary ischemia in the setting of aortic Material and methods The functional significance of 416 coronary lesions was investigated with iFR and FFR measurements in 221 AS patients. The iFR-FFR diagnostic agreement has been tested using the cut-off value for iFR of 0.89. Results Mean value of %DS was 58.6±13.4%, FFR was 0.85±0.07 and iFR – 0.90±0.04. FFR ≤0.80 was measured in 26.0% of interrogated vessels, iFR ≤0.89 – in 33.2%. The correlation between iFR and FFR was good (r=0.83, p Conclusion In the presence of AS, FFR had good agreement with iFR values. However, FFR threshold for predicting iFR below 0.89 may be different from a standard threshold and that should be taken into account while assessing coronary physiology in the setting of AS. Funding Acknowledgement Type of funding source: Public grant(s) – National budget only. Main funding source(s): National Science Center

Background The safety of deferral of revascularization based on instantaneous wave-free ratio (iFR) is established in randomized controlled trials. However, there is little data regarding long-term outcomes after deferral of revascularization based on iFR in real-world practice. Purpose We sought to assess clinical outcomes after deferral of revascularization based on iFR in clinical practice as compared with those based on fractional flow reserve (FFR). Methods This is a post hoc analysis of the J-CONFIRM registry (long-term outcomes of Japanese patients with deferral of coronary intervention based on fractional flow reserve in multicenter registry), in which 1262 patients with 1447 lesions deferred the revascularization based on FFR. Of these, both FFR and iFR were measured in 399 patients with 452 lesions. The patients were classified into the two groups: the iFR group (iFR >0.89; 308 patients with 348 lesions) and the FFR group (FFR >0.80; 740 patients with 855 lesions). The primary study endpoint was the 3-year target vessel failure (TVF) including cardiac death, target-vessel related myocardial infarction (TVMI), and clinically driven target vessel revascularization (CDTVR). Results Mean iFR was 0.96±0.04 in the iFR group. Mean FFR was significantly lower in the iFR group than in the FFR group (0.87±0.05 vs. 0.89±0.05, p=0.002). The iFR group included 35 lesions (11.4%) with FFR ≤0.80. At 3 years, the rate of TVF on a lesion basis were not significantly different between the iFR and FFR groups (8.8% vs. 6.1%, p=0.10), whereas CDTVR rate was significantly higher in the iFR group than in the FFR group (8.5% vs. 5.3%, p=0.044). Cardiac death and TVMI on a patient basis rarely occurred in both groups during the 3-year follow-up (0.33% vs. 0.77%, p=0.47; 0.66% vs. 0.56%, p=0.85, respectively). Conclusion At 3 years, TVF rate in deferred lesions was numerically higher in the iFR group than in the FFR group, driven by a higher rate of CDTVR. However, cardiac death and TVMI was very rare in both groups, highlighting the safety of both iFR- and FFR-based deferral of revascularization in daily practice. Funding Acknowledgement Type of funding source: None

Background The trial collected prospective data from physiology measurements of borderline lesions in five Czech, one Japan and one Argentinian cathlabs. The main purposes were to analyze diagnostic agreement between FFR (fractional flow reserve) and iFR (instantaneous wave free ratio) examinations and to find possible explanations for discrepant results. Methods FFR and iFR examinations were analyzed using Philips-Volcano console and coronary flow reserve (CFR) was analyzed by using Combomap machine Philips-Volcano. Hyperemia for FFR and CFR measurements was induced by intracoronary administration of adenosine. We used CFR as a truth for comparison between FFR and iFR, because CFR has higher impact on patients prognosis than pressures indices. Results Data were collected from February 2016 to June 2019 and the database includes 1.789 examinations from 1.492 patients (282 of them, 15.8%, with ACS). CFR were measured in 343 lesions in 293 patients. (ACS 31.2%). Overall correlation between FFR and iFR is high (R=0.86 p Conclusion The FFR/iFR discrepancy occurred in almost one quarter of examinations. Correlation between CFR and iFR is better than between CFR and FFR. High flow is probably one of the main reason for FFRp/iFRn type of discrepancy. Funding Acknowledgement Type of funding source: Public grant(s) – National budget only. Main funding source(s): Czech Health Research Council

Background The functional assessment of coronary artery disease (CAD) in patients with severe aortic stenosis (AS) has been barely examined so far, and the best strategy to physiologically investigate the relevance of coronary stenosis in this specific setting of patients remains undetermined. The aim of the study is to compare the diagnostic performance of instantaneous wave-free ratio (iFR), quantitative flow ratio (QFR) and fractional flow reserve (FFR) in patients with severe AS. Methods The functional significance of 416 coronary lesions was investigated with iFR, FFR and QFR measurements in 221 AS patients. The iFR-FFR and QFR-FFR diagnostic agreement has been tested using the conventional 0.80 FFR cut-off. Results Mean value of FFR was 0.85±0.07; iFR – 0.90±0.04; QFR – 0.84±0.07. The correlation between iFR and FFR was good (r=0.83, p Conclusions In the presence of severe AS, iFR and QFR had good agreement with FFR values for assessment of borderline coronary lesions. However, iFR threshold for predicting FFR below 0.8 may be different from a standard value of 0.89. Funding Acknowledgement Type of funding source: Public grant(s) – National budget only. Main funding source(s): National Science Centre

Background Patient- and lesion-related factors may influence concordance between instantaneous wave-free ratio (iFR) and fractional flow reserve (FFR), potentially affecting safety of revascularization deferral. Methods Consecutive patients with at least an intermediate coronary stenosis evaluated by both iFR and FFR were retrospectively enrolled. Revascularization was at physician's discretion. The agreement between IFR and FFR at their diagnostic cut-offs (FFR 0.80, iFR 0.89) according to patient- and lesion-level characteristics was assessed. Multivariate analyses were carried to identify the independent predictors of discordance. Tailored iFR cut-offs according to predictors of discordance best matching an FFR of 0.80 were identified by receiver-operating characteristic (ROC) curves. The impact of reclassification according to tailored iFR cut-offs on major cardiovascular events (MACE: cardiovascular death, myocardial infarction or target lesion revascularization) among deferred lesions was investigated. Results 299 coronary stenosis (diameter stenosis 54±14%, FFR 0.84 [0.78–0.89], iFR 0.91 [0.87–0.95], left main/left anterior descending [LM/LAD] vessel 67.6%) of 260 patients were studied, and 46.5% were revascularized. Discordance rate was 23.4% (10.7% iFR-negative discordant, 12.7% iFR-positive discordant). Independent predictors of discordance were LM/LAD disease, multivessel disease, non-ST-elevation myocardial infarction presentation, smoking, reduced glomerular filtration rate and hypertension. Lesion reclassification with tailored iFR-cut-offs based on patient-level predictors carried no prognostic value among deferred lesions. Reclassification according to lesion location, which was entirely driven by LM/LAD lesions (iFR-cut-offs: 0.93 for LM/LAD, 0.89 for non-LM/LAD), identified increased MACE among lesions deferred based on a negative FFR, between patients with a positive as compared to a negative iFR (19.4% vs. 6.1%, p=0.044), while the same association was not observed with the conventional 0.89 iFR cut-off (15.0% vs 8.6%, p=0.303). Conclusion Tailored vessel-based iFR cut-offs carry prognostic value among FFR negative lesions, suggesting that iFR may more safely defer revascularization of LM/LAD lesions than FFR and that a single iFR cut-off might be clinically unsatisfactory. Funding Acknowledgement Type of funding source: None

Background Wall shear stress (WSS) plays an important role in coronary atherosclerosis. Low WSS is associated with inflammation, endothelial dysfunction, and progression of atherosclerosis; while high WSS leads to vulnerable plaque transformation and future myocardial infarction. Defining the relationship between WSS and the currently available coronary physiology indices would provide valuable insights into potential mechanisms for predicting future adverse cardiac events. Purpose To investigate the relationship between WSS and the coronary epicardial/microvascular physiology indices. Methods Patients undergoing coronary angiography and physiology testing were prospectively recruited. Physiology measurements were performed under resting and hyperaemic conditions using a pressure/temperature sensor guidewire. Fractional flow reserve (FFR), non-hyperaemic pressure ratios (NHPRs), coronary flow reserve (CFR), and corrected index of microcirculatory resistance (IMR) were measured. The NHPRs including resting full-cycle ratio (RFR), resting distal/aortic pressure (Pd/Pa), instantaneous wave-free ratio (iFR), diastolic pressure ratio (dPR) and diastolic hyperaemia-free ratio (DFR) were derived offline by a blinded expert reader. Values of FFR ≤0.80, NHPR ≤0.89, CFR 25 were considered ischaemic/abnormal. Computational fluid dynamics analysis was performed and fluid motion equations were solved using finite-volume based software. The inlet and outlet boundary conditions were set to the patient-specific Pa and Pd respectively. The lesion WSS, mean WSS in five segments (WSSupstream = 5mm proximal to lesion, WSSprox = proximal third of lesion, WSSmid = middle third of lesion, WSSdistal = distal third of lesion, WSSdownstream = 5mm distal to lesion), and the total area of low WSS (defined as Results A total of 112 vessels from 93 patients were included in the study. The total area of low WSS was significantly larger in lesions with ischaemic FFR, NHPRs, and CFR values (Figure B), and not significantly different in lesions with abnormal IMR values. There was no significant difference in lesion WSS between groups stratified by all physiology indices. Within the lesion WSS sub-segments, WSSprox was significant higher in ischaemic lesions stratified by normal/abnormal FFR, iFR, and dPR (4.2 vs 3.3 Pa, 4.2 vs 3.3 Pa, 4.3 vs 3.3 Pa respectively, all p=0.04), and not significantly different when stratified by RFR, DFR, Pd/Pa, CFR, and IMR. Conclusion Functionally significant coronary lesions classified by the epicardial physiology indices have significantly larger total area of low WSS and higher WSSprox which may explain the higher cardiovascular event rates in patients with ischaemic lesions. There was no significant relationship between WSS and coronary microcirculatory resistance. Figure 1 Funding Acknowledgement Type of funding source: Foundation. Main funding source(s): National Heart Foundation of Australia Health Professional Scholarship

Background Provisional side-branch stenting strategy is one of the preferred strategies for treatment of bifurcation lesions. Whereas using fraction flow reserve (FFR) for the physiologic assessment of jailed side branches is well studied, the reliability of resting indices such as instantaneous wave free ratio (iFR) is unknown. Methods Consecutive patients with provisional stenting of a bifurcation and a jailed side branch were enrolled in this study. FFR and iFR were measured and, after assuring absence of baseline shift and drift, both measurements were repeated after 3 minutes. Hyperemia was induced by intra-coronary adenosine with a dose of 48μg for the right coronary artery and 96μg for the left coronary artery. Cut-off for the assumed functional significance of a stenosis was 0.80 for FFR and 0.89 for iFR. The decision to treat the side branch was left to the interventionalist's discretion. Results 37 jailed side branches in 36 patients (age 68.4±8.2; male 81% (n=29)) were consecutively enrolled in the study. The main vessel was the left main in 3% (n=1), the left anterior descending (LAD) in 65% (n=24), the diagonal branch (D1) in 3% (n=1), the left circumflex artery (LCX) in 24% (n=9) and the right coronary artery (RCA) in 5% (n=2). The Medina classification revealed true bifurcation stenosis defined as Medina 1–1-1 prior to treatment in 35% (n=13). FFR showed 35% (n=13) of the stenosis to be functionally significant with a high reproducibility of the results (r=0.986). FFR showed a low correlation with angiographic assessment (r=−0.477). iFR indicated hemodynamic relevance in 38% of lesions (n=14) with a high reproducibility (r=0.967) and also correlated poorly with angiographic assessment (r=−0.271). iFR was found to closely correlate with FFR in jailed side branches (r=0.720, Figure 1A). Bland-Altman analysis showed iFR and FFR agreed with a mean difference between FFR and iFR of −0.054±0.146. In 81% (n=30) FFR and iFR showed the same results regarding functional significance. In 8% (n=3) FFR was ≤0.80 and iFR >0.89, in 11% (n=4) FFR was >0.80 and iFR was ≤0.89 (Figure 1B). Side branch treatment was performed in 32% (n=12). All of these lesions showed functional significance in FFR or iFR. Stent implantation was performed in 8% (n=3), balloon angioplasty in 19% (n=7) and balloon angioplasty with a drug-eluting balloon in 5% (n=2). Conclusions The results of this study confirm the poor correlation of angiographic and functional assessment of coronary artery stenoses. Our data show close agreement of iFR and FFR in stent-jailed side branches. Therefore, iFR can be considered as a reliable technique for guidance of provisional side branch stenting. Figure 1 Funding Acknowledgement Type of funding source: None

Introduction Fractional flow reserve (FFR) is a gold standard method to evaluate functional lesion severity in daily clinical practice. Recently, the resting full-cycle ratio (RFR) which was newly developed resting indices was launched. Unlike other resting indices evaluated in diastolic phase, RFR is evaluated during entire cardiac phase. Previous studies showed discordance predictors between FFR and instantaneous wave-free ratio. However, it is previously unreported what predictor cause discordant outcome between FFR and RFR. Purpose The purpose of this study was to evaluate clinical predictors of discordance between FFR and RFR. Methods A total of 156 patients with 220 lesions were prospectively enrolled in this study. RFR was evaluated before inducing hyperemia. FFR was measured after intravenous adenosine triphosphate administration (180 mcg/kg/min). According to FFR and RFR values, the patients and lesions were classified into 4 groups: Concordant negative (Group-1 [n=114]: FFR >0.80, RFR >0.89); negative FFR and positive RFR (Group-2 [n=18]: FFR >0.80, RFR ≤0.89); positive FFR and negative RFR (Group-3 [n=25]: FFR ≤0.80, RFR >0.89); Concordant positive (Group-4 [n=63]: FFR ≤0.80, RFR ≤0.89). Among them, discordance predictors with clinical characteristics between RFR and FFR were compared using by two separate logistic regression analyses. (Group-1 vs. Group-2, Group-3 vs. Group-4, respectively). Age, sex and those predictors with a p value ≤0.10 were included in a multivariate regression analysis using by forward stepwise selection to identify independent predictors of discordance. Results On multiple regression analysis, hemodialysis (HD) (OR:6.072 [1.090–33.836]), peripheral artery disease (PAD) (OR:9.053 [1.776–46.162]) and left anterior descending artery (LAD) (OR:9.264 [2.092–41.031]) were significantly associated with positive RFR among negative FFR groups (Groupe 2 discordance). Conversely, diabetes mellitus (DM) (OR:0.212 [0.062–0.721]) and Hb (OR:1.480 [1.102–1.987]) were significantly associated with negative RFR among positive FFR groups (Groupe 3 discordance) Conclusions Since the clinical characteristics with HD, PAD, LAD, DM and Hb may influence concordant with FFR during RFR evaluation, it should be considered when interpreting RFR. Distribution and independent predictors Funding Acknowledgement Type of funding source: None

Background It has been reported that discordance between fractional flow reserve (FFR) and Instantaneous Wave-Free Ratio (iFR) could occur in up to 20% of cases. However, there are no reports regarding discordance between FFR and iFR in patients with severe aortic valve stenosis (AS). Purpose We aimed to investigate the discordance between FFR and iFR in patients with severe AS. Methods Severe AS was defined as an aortic-valve area of ≤1.0 cm2, a mean aortic-valve gradient of 40mmHg or more, or a peak aortic-jet velocity of 4.0 m/s or more. Intermediate coronary artery stenosis was defined as 30% to 70% stenosis (visual estimation). FFR and iFR were calculated in 4 quadrants based on values of FFR ≤0.8 and iFR ≤0.89 (positive discordance; low FFR and high iFR, negative discordance; high FFR and low iFR). Results We examined consecutive 140 patients (164 intermediate coronary artery stenosis vessels). Mean FFR and iFR ± standard deviation was 0.82±0.09 and 0.82±0.14, respectively. The discordance was observed in 48 vessels (29.3%). In the discordant group, most of cases were negative discordance (45 cases, 93.6%). Binary logistic regression analysis showed that left anterior descending artery (Hazard Ratio 3.80; 1.55 to 9.31, p=0.0036) was independently associated with negative discordance. Conclusions In patients with severe AS, the discordance between FFR and iFR could be observed in 29.3% of the vessels, mostly negative discordance. The left anterior descending artery is an independent predictor for negative discordance. Funding Acknowledgement Type of funding source: None

AIMS We evaluated diagnostic accuracy of CT-fractional flow reserve (CT-FFR) computed on-site with a new vendor workstation, against invasive FFR as the reference standard. METHODS AND RESULTS Retrospective analyses compared CT-FFR of 104 vessels with 30-90% diameter stenosis in 75 patients imaged using single-rotation 320 detector-row coronary CT angiography (CCTA) with invasive FFR performed within 90 days. Prospective ECG-gated CCTA included exposure of 70-99% of the R-R interval. CT-FFR was computed on-site within the same physical space as the CT scanner and reading room. The diagnostic accuracy of CCTA >50% and CT-FFR ≤0.8 to detect hemodynamically significant stenosis, defined as FFR ≤0.8, was determined, as was the correlation of CT-FFR to FFR and instantaneous wave-free ratio (iFR). Forty-four vessels (42.3%) had an invasive FFR ≤0.8. The sensitivity, specificity, positive, and negative predictive value of CT-FFR ≤0.8 vs. CCTA >50% to detect hemodynamically significant stenosis defined as FFR ≤0.8 were 90.9% vs. 70.5%, 78.3% vs. 43.3%, 75.5% vs. 47.7%, and 92.2% vs. 66.7%, respectively. Area under the curve of CT-FFR was significantly higher than CCTA >50% [0.85, 95% confidence interval (CI): 0.76-0.91 vs. 0.57, 95% CI: 0.47-0.67; P

Item does not contain fulltext For identification of myocardial ischaemia by non-invasive imaging or invasive physiological assessment, administration of a vasodilating or positive inotropic agent is often considered indispensable to exhaust the cardiac compensation mechanisms. Indeed, microcirculatory dilatation is needed for assessment of myocardial perfusion or coronary blood flow. However, three different modalities exist that quantify myocardial ischaemia without recourse to pharmacological stress agents, using either myocardial contrast echocardiography, imaging of myocardial blood volume or invasive coronary pressure measurement with the instantaneous wave-free ratio (iFR). The theoretical framework of these vasodilator-free modalities revolves around the two innate mechanisms that protect the myocardium from ischaemia at rest: coronary autoregulation and arteriogenesis. Coronary autoregulation and metabolic dilatation form the putative processes that regulate microvascular tone and constitute of a complex interplay between metabolic factors, myogenic control, and endothelium-based control that each interact with coronary arterioles of a different size. Arteriogenesis describes the development of large calibre collateral arteries from a pre-existing network, triggered by occlusive coronary artery disease. Following these descriptions, the fundamental principles and the existing evidence of these three diagnostic modalities are reviewed. Emphasis is placed on iFR, which is clinically best applicable. Instantaneous wave-free ratio has proven to be an effective method to determine the haemodynamic significance of coronary stenoses in two recent large randomized clinical trials, together enrolling over 4500 patients. Ultimately, this review aims to clarify the theoretical rationale and to describe the clinical implications of functional stenosis assessment under resting conditions.

Background The clinical implication of state-of-art PCI at long term follow-up in patients with three vessel disease is undetermined. Purpose The purpose of the study was to investigate whether the favourable outcomes of state-of-the-art PCI in the SYNTAX-II trial, demonstrated up to 2 years, are maintained at 3-year follow-up. Methods The SYNTAX-II study was a multicentre, single arm study that investigated the impact of a state-of-art PCI strategy on clinical outcomes in patients with de novo three vessel coronary artery disease, without left main disease. State-of-art PCI includes: heart team decision-making utilizing the SYNTAX score II, hybrid iFR-FFR decision-making strategy, intravascular ultrasound guided stent implantation, contemporary chronic total occlusion revascularization techniques and guideline-directed medical therapy. The primary endpoint is major adverse cardiac and cerebrovascular events (MACCE – a composite of all-cause death, any stroke, myocardial infarction, or revascularization) at 3 years. Clinical outcomes in SYNTAX-II were compared to the predefined PCI (SYNTAX-I PCI) and coronary artery bypass graft (SYNTAX-I CABG) cohorts from the landmark SYNTAX Trial (SYNTAX-I), selected on the basis of equipoise for long-term (4-year) mortality utilising the SYNTAX Score II. Results Between February 2014 and November 2015, 454 patients out of 708 screened patients were enrolled in SYNTAX-II. In SYNTAX-I, 643 (58.8%) patients with 3VD without left main disease had an equipoise recommendation for CABG or PCI based on the SYNTAX Score II and were used as the comparator. At 2 years, MACCE rate in SYNTAX-II was significantly lower compared to SYNTAX-I PCI (13.2% vs. 21.9%, p=0.001). Furthermore, similar two-year outcomes for MACCE were evident between SYNTAX II-PCI and SYNTAX-I CABG (13.2 vs. 15.1%, p=0.42). Three-year results will be presented at ESC2019. Conclusions Three-year results of his study may offer an attractive option of revascularization strategy in predefined patients with de novo 3VD (SYNTAX Score II inclusion) even if the patients have moderate to severe anatomical complexity (anatomic SYNTAX score >22). Acknowledgement/Funding European Cardiovascular Research Institute (ECRI) with unrestricted research grants from Volcano and Boston Scientific

Background It has been reported that preoperative fractional flow reserve (FFR) is associated with graft patency after coronary artery bypass graft (CABG) and the patency is excellent when a bypass graft is anastomosed on a vessel with positive FFR. However, the association with graft patency has not yet been investigated in its novel counterpart, instantaneous wave-free ratio (iFR), and iFR sometimes contradicts FFR results. Purpose The purpose of this study is to assess an impact of preoperative iFR on a graft failure after CABG in patients with coronary arteries showing positive FFR (≤0.80). Methods We retrospectively identified patients who had undergone preoperative coronary angiography in conjunction with resting and hyperemic intra-coronary pressure measurements, CABG, and graft evaluation by coronary computed tomography angiography. After excluding vessels with negative FFR (>0.80), vessels were divided into two groups: negative iFR group (iFR >0.89) and positive iFR group (iFR ≤0.89). The rate of graft failure within 1 year after CABG was compared between the two groups. Results We analyzed 131 vessels in 89 patients (35 vessels in the negative iFR group and 96 vessels in the positive iFR group). The negative iFR group showed significantly higher iFR (0.92±0.02 vs. 0.74±0.13, P Conclusions Even when FFR is positive, the graft failure is likely to occur when a bypass graft is anastomosed on a vessel with negative iFR compared to a vessel with positive iFR. Acknowledgement/Funding None

Background The usefulness of fractional flow reserve (FFR) and instantaneous wave-free ratio (iFR) evaluation has been confirmed in the determination of revascularization of coronary artery disease. When FFR≤0.8 and iFR≤0.89 were regarded as the criteria for positivity, the discordance was noted in approximately 20%, but this cause has not been well established. Purpose The purpose of this study was to investigate the patient background and features on coronary CT angiography (CCTA) showing the discordance between FFR≤0.8 and iFR≤0.89. Methods The subjects were consecutive 85 cases with 108 vessels in which stenosis of 30–90% was detected at one vessel of at least 2mm or more in the major epicardial vessels and FFR and iFR was performed within subsequent 90 days, among suspected cases of coronary arterial diseases which underwent CCTA. The factors showing the discordance between FFR and iFR (patient background, coronary artery calcification score, high risk plaque features on CCTA (positive remodeling, low attenuation plaque), plaque characteristics by a plaque analysis software using a new algorithm called labeling method (vessel volume, plaque volume, lumen volume, plaque length, maximum plaque burden, necrotic core area, fibrous area and calcium area) were evaluated using logistic regression analysis on per-patient and per-vessel basis. Results There were no significant both FFR and iFR positive definite factors on per-patient basis. The lumen volume/vessel volume (OR: 0.93, 95% CI: 0.88–0.98, P=0.0032) (OR: 0.90, 95% CI: 0.85–0.95, P Conclusions In both FFR and iFR, only lumen volume /vessel volume, MLA, plaque volume/vessel volume and plaque burden were significant positive definite factors. As for the discordance between FFR and iFR, PR is significant predictor in FFR positive and iFR negative group.

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2017