Instantaneous Wave-free Ratio Research Articles

Instantaneous Wave-Free Ratio: Novel Adenosine-Free Method to Assess Intracoronary Physiology.

Fractional flow reserve assessment was accepted as a crucial strategy in stable patients undergoing coronary angiography without prior noninvasive evaluation in the presence of borderline lesions and in patients with multivessel coronary artery disease. Instantaneous wave-free ratio, measured during a specific diastolic interval, emerged as a nonhyperemic pressure ratio. Due to its advantages such as not requiring a vasodilating agent, rapidity of procedure, pullback phenomena for the assessment of individual stenosis in tandem lesions or diffusely infiltrated vessels, and virtual percutaneous coronary intervention which allows the assessment and justification 'of' optimal coronary revascularization, instantaneous wave-free ratio became a valuable option in the field of coronary physiology. This review aims to address coronary physiological concept with fractional flow reserve and emergence of instantaneous wave-free ratio through cornerstone studies as well as the use of instantaneous wave-free ratio in different clinical scenarios.

Instantaneous wave–free ratio (IFR) VS myocardial perfusion imaging by single photon emission tomography (MPI-SPECT) in assessment of significance of moderate coronary artery disease

Instantaneous wave–free ratio (IFR) VS myocardial perfusion imaging by single photon emission tomography (MPI-SPECT) in assessment of significance of moderate coronary artery disease

Angiocoregistration of instantaneous wave-free ratio using “virtual stenting” and results of real stenting in patients with coronary artery disease and diffuse coronary artery lesions

Angiocoregistration of instantaneous wave-free ratio using “virtual stenting” and results of real stenting in patients with coronary artery disease and diffuse coronary artery lesions

Impact of diabetes mellitus on the diagnostic performance of fractional flow reserve in patients with severe aortic stenosis.

The validity of functional assessment of coronary artery disease with fractional flow reserve (FFR) and/or instantaneous wave-free ratio (iFR) in patients with severe aortic stenosis (AS) might be affected by AS per se and other factors, including diabetes mellitus. We aimed to evaluate the impact of diabetic status on FFR performance in severe AS. The functional significance of 416 stenoses of intermediate angiographic severity in 221 patients with severe AS was assessed with iFR and FFR. Patients treated with insulin or oral hypoglycemic agents were classified as diabetic patients. Of 221 enrolled patients, 68 (32.1%) patients were diabetic. A total of 128 (30.8%) lesions in patients with and 288 in patients without diabetes mellitus were assessed. The mean (SD) FFR was 0.85 (0.07), and iFR was 0.90 (0.04) with no difference between nondiabetic and diabetic patients. Good agreement between iFR and FFR was confirmed for non-diabetic (ICC, 0.83 [95% confidence interval, CI, 0.79-0.86]) and diabetic (ICC, 0.82 [95% CI, 0.76-0.87]) patients. Among patients without diabetes mellitus, the optimal cutoff value for FFR to detect iFR ≤0.89 was 0.81 with sensitivity and specificity of 96.6% and 100.0%. The optimal cutoff value for FFR to detect iFR ≤0.89 for diabetic patients was 0.83 with sensitivity and specificity of 98.0% and 100.0%. In patients with severe AS, FFR correlates well with iFR. However, the optimal threshold for FFR to identify significant ischemia (iFR ≤0.89) in those patients may differ from the standard threshold of FFR ≤0.80 and might be affected by the diabetic status.

Novel Humanized Biosimulator to Predict Coronary Obstruction in High-Risk Valve-in-Valve Procedures

We developed humanized biosimulator to predict the risk of coronary obstruction among high-risk patients undergoing valve-in-valve (ViV) procedures. In this case, based on unchanged instantaneous wave-free ratio values measured during a ViV simulation session, the procedure was performed safely in the patient the day afterward, without coronary artery issues and with good hemodynamic results. (Level of Difficulty: Advanced.)

666 OBSTRUCTIVE CORONARY ARTERY DISEASE: WHEN CORONARY ANGIOGRAPHY IS NOT ENOUGH.

Abstract Background Coronary angiography is the gold standard approach to assess coronary artery disease, especially in acute settings. Additional morphological and functional methods such as intravascular ultrasound (IVUS), optical coherence tomography (OCT), and fractional flow reserve or instantaneous wave free ratio (FFR or iFR) are used to confirm hemodynamic relevance of stenoses, to characterise plaque morphology and vessel size and to optimise stent implantation. This abstract presents a clinical case in which intracoronary imaging, in particular OCT, was essential in proper diagnosis and treatment of a patient presenting with acute coronary syndrome (ACS). Case Summary A 43-year-old female patient with no cardiac medical history presented with new onset chest pain occurring at rest from the night before. At admission, a 12-lead ECG showed sinus rhythm with negative T-waves in the precordial leads, hypokinesia of the anterior and apical wall of the left ventricle was found at echocardiography, and high sensitive cardiac troponin was slightly elevated at the first two measurements. The patient was admitted to the Intensive Coronary Unit with the diagnosis of non-ST segment elevation myocardial infarction and underwent coronary angiography within 24 hours of presentation. A slightly inhomogeneous distribution of dye was found at the ostium of left anterior descending artery (LAD). It was interpreted as a possible type 3 spontaneous coronary artery dissection or as the presence of a non obstructive stenoses. No significant findings were observed in the other cardiac vessels. Due to the discrepancy between the clinical presentation and the angiographic findings, additional morphological and functional assessment of LAD was performed. The OCT revealed the presence of an eccentric obstructive plaque on ostial LAD, and the functional study with FFR confirmed the hemodynamic significance of the stenosis. The patient therefore underwent revascularization with drug-eluting stent implantation on left-main/LAD axis; post-angioplasty OCT confirmed the correct stent position. The patient remained hemodynamically stable during the following hospital stay and was discharged on day 7, with a preserved global left ventricular function and persistence of apical wall hypokinesia, slow ECG evolution with regression of negative anterior T-waves and no sign of necrosis was also observed. Discussion There are several angiographically undetectable lesions that can be identified only by IVUS or OCT. In this case the angiographic findings were of difficult interpretation, coronary angiography alone would have been inconclusive and would have led to the diagnosis of myocardial infarction with non-obstructive coronary arteries. This case highlights the importance of intravascular imaging and functional study to guide revascularization also in the acute settings of an ACS.

405 A NATURAL HISTORY OF VERY LONG-TERM BIORESORBABLE ATHEROSCLEROTIC RESTORATION THERAPY

Abstract A 49-year-old man was referred to our cath-lab in 2015 after the detection of inducible ischaemia in the infero-lateral wall on single-photon emission CT performed due to a worsening stable angina. His cardiovascular risk factors accounted for family history of ischemic disease, high blood pressure and dyslipidaemia. The echocardiography highlighted a mildly reduced left ventricular function with infero-lateral wall hypokinesia. Coronary angiography revealed a chronic total occlusion (CTO) of the left circumflex artery (LCX) and a long diffuse severe disease of the right coronary artery (RCA). The left anterior descending artery (LAD) showed a diffuse atherosclerotic involvement without critical stenoses. Percutaneous coronary intervention (PCI) was performed after Heart Team discussion with implantation of two 3.5×28mm and 3.5×23mm Absorb bioresorbable vascular scaffold (BVS) on the RCA. Moreover, the LCX CTO was successfully treated by anterograde approach with implantation of a 3.0×28 mm Absorb BVS. Intravascular ultrasound confirmed the optimal result of both the interventions, while confirmed the long diffuse calcific involvement of the LAD with a thick cap calcific fibroatheroma at the virtual histology. The patient was discharged on dual antiplatelet therapy for twelve months. After five uneventful years, he was readmitted to our department for recurrence of worsening stable angina. At the coronary angiography a significant progression of the proximal LAD disease was noted. The lesion was judged hemodynamic relevant with pressure derived indices (instantaneous wave-free ratio 0.86; fractional flow reserve 0.70). The IVUS and optical coherence tomography (OCT) analysis confirmed the significant progression of the disease with a long, diffuse, sub-occlusive thick cap fibroatheroma stenosis (minimal lumen area 1.9 mm2; plaque burden 91%). The OCT analysis showed the complete resorption of the devices previously implanted to the RCA and the LCX, with optimal long-term results and positive remodelling in the LCX. Therefore, an OCT-guided PCI with marker-to-marker implantation of two 3.5×25 and 3×20 mm magnesium-based Magmaris BVS was performed. In 2022, the patient underwent an elective coronary angiography that demonstrated a complete resorption of both the Magmaris with an optimal OCT result. Conversely, the positive remodelled segment resulting from complete resorption of the poly-L-lactic-based BVS in the mid-LCX was shown to be progressed to a critical sub-occlusive fibroatheroma. A further OCT-guided PCI with deployment one 3.5×20mm Magmaris BVS was performed. Six months later, patient was asymptomatic with a good performance status. To the best of our knowledge, the present is the first case of multivessel repetitive imaging-based percutaneous revascularizations with the use of two different BVS technologies and a total of six devices implanted, with very long-term intracoronary imaging result. Through the paired intravascular imaging analysis, this case sought to provide insightful findings on vulnerable plaque atherosclerotic progression and on BVS biologic restoration therapy, a process that appears particularly appealing in young patients with advanced CAD, namely multivessel involvement and diffuse disease that still poses limitations to PCI.

Invasive Coronary Physiology Study in Multivessel Coronary Artery Disease

AbstractAssessment of relationship between the angiographic stenosis severity and the coronary blood flow is complex. Coronary angiography has many limitations that may impair the judgment of stenosis severity and then affect decision-making regarding intervention. Myocardial perfusion imaging by single-photon emission tomography (MPI-SPECT) is used for a long time to help clinical decisions of interventions, but has limitations, such as issues with identification of extensive coronary artery disease (CAD). Fractional flow reserve (FFR) is a gold standard index for investigating the physiological significance of a coronary stenosis. The instantaneous wave-free ratio (iFR) is a hyperemia-free measurement and easier method to achieve physiological assessment to measure the severity of coronary stenosis. We present a case of multivessel coronary artery disease (MVCAD) patient who was treated with iFR-guided percutaneous coronary intervention (PCI) and emphasize the importance of physiological assessment in PCI.A 63-year-old male with multiple cardiovascular risk factors came to our center with chief complaint of stable angina since 1 year. He underwent MPI-SPECT and the result showed 2.5% of ischemia burden. Coronary angiography showed MVCAD. Surgical conference decided to do PCI. iFR-guided PCI was performed in this case.Our case highlights the importance of iFR as an important cardiology–physiology-based tool as a guide in management decisions for MVCAD. iFR as an alternative approach to physiological study is noninferior compared with FFR-guided PCI.

Functional assessment of serial coronary lesions and diffuse coronary disease

Functional assessment performed during diagnostic coronary angiography has gained an increasing role during the last few decades. Traditional coronary angiography using only anatomical data cannot provide information whether intermediate lesions cause ischaemia or not, and frequently there is no evidence from non-invasive functional tests with appropriate sensitivity and specificity to guide us regarding the localization and severity of ischaemia. Several studies proved the clinical benefit of the use of invasive functional tests. The functional severity of unrevascularized coronary artery disease is correlated with prognosis. It is important to precisely define the lesions causing ischaemia when we plan to improve the blood supply to the heart. The functional assessment of diffuse or serial lesions is not well established. New investigations and methods have been developed such as pullback pressure gradient or instantaneous wave-free ratio intensity besides the well-established and studied functional tests. This could help us find and revascularize the lesions within a coronary vessel primarily responsible for ischaemia and symptoms or, in the case of diffuse disease and no obvious target, to optimize medical therapy. Orv Hetil. 2022; 163(48): 1902-1908.

Jailed pressure wire technique for coronary bifurcation lesions: structural damage and clinical outcomes

Introduction and objectivesThe use of a pressure wire as a jailed wire to evaluate side branch results during provisional stenting seems feasible. However, safety concerns exist due to the mechanical damage of the wire and the lack of prospective data evaluating the prognosis of patients treated using this technique. This study sought to evaluate the structural damage of the pressure wire in patients treated using the jailed pressure wire technique and to assess mid-term clinical outcomes. MethodsWe enrolled 99 patients with single bifurcation lesions and provisional stenting as the strategy of choice. A jailed pressure wire was used to guide side branch intervention according to the instantaneous wave-free ratio (iFR). A total of 114 patients and the respective nonpolymer-coated jailed wires were used as historical controls. Guidewire damage was evaluated by stereomicroscopy. The primary endpoint was significant microscopic damage. Major adverse cardiac events were evaluated at 2-year follow-up. ResultsSignificant microscopic damage was more frequent in pressure wires than in nonpolymer-coated wires (53.5% vs 22.8%, P<.001). There were no fractures in either group. There were fewer side branch interventions in the pressure wire group (postdilation/kissing balloon, 32.3% vs 56.1%, P=.001; stenting, 0.0% vs 2.6%, P=.104). The 2-year rate of major adverse cardiac events was similar between the 2 groups (HRadj, 0.42; 95%CI, 0.10-1.73; P=.229). ConclusionsPressure wires were less resistant to jailing than conventional nonpolymer-coated wires. Patients treated with iFR-guided provisional stenting required fewer side branch interventions but had similar 2-year clinical outcomes than patients treated with the angiography-guided technique.

Personalized computational estimation of relative change in coronary blood flow after percutaneous coronary intervention in short-term and long-term perspectives

Abstract Coronary artery disease is the leading cause of mortality worldwide, accounting for 12.8% of all deaths. Although the clinical benefits of treating stenosis with percutaneous coronary intervention (PCI) have been extensively demonstrated, residual myocardial ischemia remains in about 30–50% of patients even after a formally successful PCI. We apply previously developed and validated 1D model of haemodynamics, which distributes terminal hydraulic resistance based on the diameters of the parent vessels and Murray’s law by a recursive algorithm. In our new model the terminal resistance is decreased according to a transmural perfusion ratio increase. In contrast to our previous work we calculate the transmural perfusion ratio for personally defined zones. Thus, peripheral hydraulic resistance of myocardial perfusion is personalized based on patient data, whichwere extracted from computed tomography perfusion images. The model serves as a computational tool for simulating pre- to post-PCI changes in coronary haemodynamics of four patients. We simulate fractional flow reserve (FFR), coronary flow reserve (CFR), instantaneous wave-free ratio (iFR), average flow in selected arteries in hyperemic and rest conditions before PCI and after PCI immediately after the surgery (in a short-term) and in a long-term (several months) perspectives. We conclude that high FFR and iFR values in short-term and long-term perspectives are not necessary correlate with CFR improvement and long-term blood flow recovery in coronary arteries.

Abstract 15187: Comparison of Resting and Hyperemic Coronary Physiological Indices to Evaluate Myocardial Bridging in Patients With Angina and No Obstructive Coronary Arteries

Introduction: A hemodynamically significant myocardial bridge (MB) is an important diagnosis in patients with angina and no obstructive coronary arteries (ANOCA). The most appropriate intracoronary functional assessment to distinguish an incidental vs. hemodynamically significant MB remains unclear. We compared the ability of several resting and hyperemic physiological indices to identify a hemodynamically significant MB. Methods: We prospectively studied 11 patients with ANOCA and an MB confirmed by intravascular ultrasound (IVUS). All patients had intracoronary functional testing at rest, including instantaneous wave-free ratio (iFR), resting full-cycle ratio (RFR), and the ratio of distal coronary pressure (Pd)/aortic pressure (Pa). These measurements were repeated at hyperemia, including adenosine fractional flow reserve (FFR), dobutamine diastolic FFR (dFFR), iFR, and RFR. Resting iFR and RFR ≤ 0.89; resting Pd/Pa ≤ 0.91; hyperemic FFR, iFR, and RFR ≤ 0.8; and dFFR ≤ 0.76 were considered indicative of hemodynamic significance of an MB. Dobutamine dFFR was considered as reference standard. Results: At rest, iFR and RFR were significant in 6 and 7 patients respectively, while Pd/Pa was significant in 6. Adenosine FFR was significant in only 4 patients. With dobutamine, iFR and RFR were significant in 8 and 9 patients, respectively, and dFFR was significant in 9. Resting Pd/Pa and hyperemic iFR had a strong positive Spearman's rank correlation coefficient with dFFR (Figure). By kappa statistics, dobutamine iFR and RFR had almost perfect agreement with dobutamine dFFR. Conclusion: In patients with ANOCA who have an MB by IVUS, intracoronary physiology assessment is necessary to determine if the MB is hemodynamic significant. While adenosine FFR is an insufficient measure, diastolic indices such as dobutamine dFFR, iFR, or RFR may identify hemodynamic significance, although whether one diastolic index outperforms another requires further evaluation.

Clinical Relevance of Impaired Physiological Assessment After Percutaneous Coronary Intervention: A Meta-analysis.

Despite the optimal angiographic result of percutaneous coronary intervention (PCI), residual disease at the site of the culprit lesion can lead to major adverse cardiac events. Post-PCI physiological assessment can identify residual stenosis. This meta-analysis aims to investigate data of studies examining post-PCI physiological assessment in relation to long-term outcomes. Studies were included in the meta-analysis after performing a systematic literature search on July 1, 2022. The primary end point was the incidence of major adverse cardiac events, vessel-orientated cardiac events, or target vessel failure. Low post-PCI fractional flow reserve, reported in 7 studies with fractional flow reserve cutoff values between 0.84 and 0.90, including 4017 patients, was associated with an increased rate of the primary end point (hazard ratio [HR], 2.06; 95% CI, 1.37-3.08). One study reported about impaired post-PCI instantaneous wave-free ratio with instantaneous wave-free ratio cutoff value of 0.95 in relation to major adverse cardiac events, showing a significant association (HR, 3.38; 95% CI, 0.99-11.6; P = .04). Low post-PCI quantitative flow ratio, reported in 3 studies with quantitative flow ratio cutoff value between 0.89 and 0.91, including 1181 patients, was associated with an increased rate of vessel-orientated cardiac events (HR, 3.01; 95% CI, 2.10-4.32). Combining data of all modalities, impaired physiological assessment showed an increased rate of the primary end point (HR, 2.32; 95% CI, 1.71-3.16) and secondary end points, including death (HR, 1.41; 95% CI, 1.04-1.89), myocardial infarction (HR, 2.70; 95% CI, 1.34-5.42) and target vessel revascularization (HR, 2.88; 95% CI, 1.91-4.35). Impaired post-PCI physiological assessment is associated with increased adverse cardiac events and individual end points, including death, myocardial infarction, and target vessel revascularization. Therefore, prospective studies are awaited on whether physiology-based optimization of PCI results in better clinical outcomes.

Comparative analysis of instantaneous wave-free ratio and quantitative real-time myocardial contrast echocardiography for the assessment of myocardial perfusion.

The field of coronary artery physiology is developing rapidly and changing the practice of interventional cardiology. A new functional evaluation technique using the instantaneous wave-free ratio (iFR) has become an alternative to fractional flow reserve. Future research studies need to determine whether physiological indicators play a role in evaluating myocardial perfusion in the catheter room. Thirty-eight patients scheduled for coronary angiography and iFR evaluation underwent a real-time myocardial contrast echocardiography (RT-MCE) examination at rest. The myocardial perfusion parameters (A, β, and A × β) on the myocardial perfusion curve were quantitatively analyzed using Q-Lab software. Coronary angiography and iFR assessment were completed within 1 week after the RT-MCE examination in all patients. Correlation analysis was used to identify iFR- and MCE-related indicators. The sensitivity and specificity of iFR in the quantitative detection of coronary microcirculation were obtained. The correlation coefficients between iFR and A, β, and A × β were 0.81, 0.66, and 0.82, respectively. The cut-off value for iFR was 0.85 for microvascular ischemia detection, while the sensitivity and specificity for the diagnosis of myocardial perfusion were 90.7 and 89.9%, respectively. The receiver operating characteristic (ROC) curve area for iFR was 0.946 in the segments related to myocardial blood flow. The iFR is an effective tool for detecting myocardial microcirculation perfusion, with satisfactory diagnostic performance and a demonstrated role in physiological indices used for the perfusion assessment.

Comparison of Six Different Percutaneous Coronary Intervention Guidance Modalities.

Background: New randomized trials and modalities in guiding percutaneous coronary intervention (PCI) have become available. Objective: We aimed to compare the clinical outcomes of coronary angiography (CAG), intravascular ultrasound (IVUS), optical coherence tomography (OCT), fractional flow reserve (FFR), instantaneous wave-free ratio (iFR), and optical frequency domain imaging (OFDI)-guided PCI. Methods: A network meta-analysis was performed to compare different PCI guidance modalities. The clinical outcomes included major adverse cardiovascular events (MACE), all-cause death, myocardial infarction (MI), and target vessel/lesion revascularization (TVR/TLR). Odds ratio (OR) and corresponding 95% credible interval (CrI) were calculated. Results: Thirty-six randomized trials, including 19,042 patients, were included. In comparison with CAG, IVUS significantly reduced MACE (OR: 0.71; 95% CrI: 0.57 to 0.86) and TVR/TLR (OR: 0.53; 95% CrI: 0.43 to 0.66). MACE (OR: 1.44; 95% CrI: 1.02 to 2.08) and TVR/TLR (OR: 1.87; 95% CrI: 1.04 to 3.71) were significantly increased in the FFR group, compared with IVUS group. There were no significant differences in MACE or TVR/TLR among the left guidance modality comparisons. Differences in all-cause death or MI were not observed in any comparisons. Conclusions: IVUS could reduce MACE and TVR/TLR, compared with CAG or FFR. Therefore, IVUS may be the optimal modality in guiding PCI.

Comparison of quantitative flow ratio (QFR) and instantaneous wave-free ratio (iFR) or resting full-cycle ratio (RFR) during daily routine in the catheterization laboratory

Abstract Background The prognosis of patients with coronary artery disease (CAD) depends strongly on the hemodynamic relevance of the stenosis. The gold standard is the invasive evaluation of the stenosis using Fractional Flow Reserve (FFR), instantaneous wave-free ratio (iFR) or Resting Full-Cycle Ratio (RFR). The use of invasive procedures remains low due to procedural factors and costs. Quantitative Flow Ratio (QFR) is a novel, software-based method to evaluate the physiology of coronary lesions during cardiac catheterization. Computing a three-dimensional model of the vessel based on two angiographic recordings and analyzing the fluid dynamics of the contrast medium flow, the software computes the FFR. In the setting of clinical studies, it has been demonstrated that QFR is feasible and correlates well with FFR. The aim of this study is to compare feasibility and reliability of QFR with established measurements of the iFR or RFR in daily routine. Methods Patients with an indication for an invasive coronary angiography and a stenosis of 30 to 90% were simultaneously assessed using QFR and iFR/RFR in a routine setting. The QFR-computation was performed online by a certified expert with QAngio XA 3D 3.2. The following outcome parameters were analyzed: time to result, volume of applicated contrast medium, applicated dose area product, result of the evaluation. The results have been registered for both methods, respectively. Results 102 coronary arteries were analyzed using QFR and iFR or RFR. QFR shows a good correlation (r=0.753, AUC=0.922) and accuracy (agreement 89.22%, sensitivity 95.83%, specificity 83.33%, PPV 83.64%, NPV 95.74%). The data show that QFR delivers significantly faster results and reduces the procedure related applicated radiation dose from in median 598.8 cGy cm2 to 306.75 cG ycm2 (p&amp;lt;0.001). The study shows no significant difference regarding the amount of contrast medium used. Conclusion QFR has a good diagnostic agreement and can reduce procedure length and applicated radiation dose. Thereby QFR could increase the use of physiologically guided coronary interventions in daily routine. Funding Acknowledgement Type of funding sources: None.

Clinical relevance of impaired physiological assessment after percutaneous coronary intervention: a meta-analysis

Abstract Background Despite optimal angiographic result of Percutaneous Coronary Intervention (PCI), residual disease at the site of the culprit lesion can lead to Major Adverse Cardiac Events (MACE) at follow-up [1]. Post-PCI physiological assessment can identify residual stenosis. Purpose The aim of this meta-analysis is to investigate data of studies with minimum follow-up of 6 months examining post-PCI physiological assessment in relation with long-term outcomes. Methods Studies were included in the meta-analysis after performing systematic search of the literature on 10th of January 2022. The primary endpoint was the incidence of MACE, Vessel-Orientated Cardiac Events (VOCE) or Target Vessel Failure (TVF). Secondary endpoints included the incidence of death, myocardial infarction (MI) and Target Vessel Revascularization (TVR). Results Low post-PCI FFR, reported in seven studies [2–8], including 4017 patients, was associated with an increased rate of the primary endpoint (HR 2.06; 95%-CI 1.37–3.08). One study reported about impaired post-PCI (instantaneous wave-free ratio) iFR in relation with MACE, showing a significant association (HR 3.38; 95%-CI 0.99–11.6) [9]. Low post-PCI QFR, reported in three studies [10–12], including 1181 patients, was associated with increased rate of VOCE (HR 3.02; 95%-CI 2.13–4.30). Combining data of all modalities, impaired physiological assessment showed an increased rate of the primary endpoint (HR 2.32; 95%-CI 1.71–3.16) and secondary endpoints including death (HR 1.35; 95%-CI 1.01–1.82), MI (HR 2.50; 95%-CI 1.36–4.58) and TVR (HR 2.88; 95%-CI 1.91–4.35). Conclusions Impaired post-PCI physiological assessment is associated with an increase in adverse cardiac events and individual endpoints including death, MI and TVR. Prospective studies are awaited whether physiology-based optimization of PCI results in better clinical outcome. Funding Acknowledgement Type of funding sources: None.

Concordant low and discordant fractional flow reserve and instantaneous wave-free ratio measurements are associated with reduced myocardial perfusion

Abstract Background In patients undergoing invasive coronary angiography with functional lesion assessment, both fractional flow reserve (FFR) and instantaneous wave-free ratio (iFR) measurements can be used to guide coronary revascularization decision-making. The hemodynamic significance of lesions with discordant FFR and iFR measurements is debated. Purpose This study compared quantitative myocardial perfusion indices as assessed by [15O]H2O positron emission tomography (PET) perfusion imaging in vessels with concordant high, discordant and concordant low FFR/iFR measurements Methods This post-hoc analysis of the PACIFIC I and II studies included 198 patients suspected of obstructive coronary artery disease who had undergone [15O]H2O PET imaging and subsequent FFR/iFR interrogation in 468 vessels. Resting myocardial blood flow (MBF), hyperemic MBF and coronary flow reserve (CFR) were compared between 4 vessel subgroups: FFR+/iFR+ (n=79), FFR−/iFR+ (n=22), FFR+/iFR− (n=22) and FFR−/iFR− (n=345). Results Discordant FFR/iFR indices were found in 44 (9%) vessels. Hyperemic MBF was significantly lower for vessels with FFR+/iFR+ (2.09±0.67 mL min–1 g–1), FFR−/iFR+ (2.41±0.80 mL min–1 g–1) and FFR+/iFR− (2.40±0.69 mL min–1 g–1) compared to FFR−/iFR− vessels (2.91±0.84 mL min–1 g–1) (p&amp;lt;0.01, p=0.03 and p&amp;lt;0.01, respectively). Hyperemic MBF did not differ between vessels with FFR+/iFR+ compared to FFR−/iFR+ (p=0.38) and FFR+/iFR− (p=0.35) vessels. In addition, resting MBF was lower and CFR did not differ in the FFR+/iFR− versus the FFR−/iFR− group (resting MBF: 0.80±0.16 mL min–1 g–1 vs. 0.90±0.24 mL min–1 g–1, p=0.03 and CFR: 3.05±0.84 vs. 3.35±1.07, p=0.56). Finally, CFR was similar in FFR+/iFR+ and FFR−/iFR+ vessels (2.37±0.76 vs. 2.64±0.84, p=0.92). Conclusions We found lower baseline flow and similar flow reserve in FFR+/iFR− compared to FFR−/iFR− vessels. Importantly, [15O]H2O PET imaging demonstrated reduced hyperemic MBF in vessels with concordant low and discordant FFR and iFR measurements. Funding Acknowledgement Type of funding sources: None.

Validation and diagnostic performance of a fast on-site deep learning-based CT-FFR algorithm

Abstract Background/Introduction CT-based fractional flow reserve (CT-FFR) has been extensively studied and established as a valuable tool for clinical decision making over the past decade. Nevertheless, clinical implementation has not been systematically adopted due to economic and technical reasons. Among the latter, the turn-around time for the computation and analysis' results potentially plays an important role. Purpose To evaluate the feasibility and diagnostic accuracy of CT-FFR computed on-site with a novel, deep learning-based algorithm using invasive hemodynamic indices as the reference standard. Methods Sixty-one patients who underwent clinically indicated coronary computed tomography angiography and invasive FFR (iFFR) and/or instantaneous wave-free ratio (iFR) measurements were retrospectively included. CT-FFR analysis was performed in 77 arteries using an on-site prototype software based on deep learning algorithms for coronary anatomy segmentation and prediction of the pressure drop under rest and hyperemia. The diagnostic performance of CT-FFR to detect hemodynamic significant lesions was assessed using iFFR (≤0.8) and/or iFR (≤0.89) as the standard of reference (60 patients with iFFR, 11 patients with iFR, and 3 patients with both) and the receiver operating characteristic area under the curve (AUC) was calculated. Furthermore, correlation analysis and Bland-Altman (BA) analysis was performed. Time for analysis including processing and manual edits to the lumen segmentation was recorded. Results CT-FFR analysis was successful in 59 (97%) patients and 74 (96%) arteries. In 74 arteries, 31 of 74 coronary lesions were invasively found to be hemodynamically significant. Total mean time for per patient CT-FFR analysis was 7 minutes and 55 seconds. Compared with invasive indices, per-lesion sensitivity and specificity of CT-FFR were 90%, and 98%, respectively. The AUC of CT-FFR vs. invasive indices for hemodynamic significance was 0.94, (95% confidence interval: 0.86–0.98). Compared to iFFR, CT-FFR correlated well (r=0.77) with only a very small bias (0.02) and narrow BA limits of agreement (−0.14 to 0.17). The per-lesion accuracy, sensitivity and specificity vs. iFFR were 96%, 93%, and 100%, respectively. Conclusion A novel deep learning-based CT-FFR algorithm yields excellent diagnostic accuracy compared to invasive hemodynamic indices to detect lesion-specific ischemia and offers the potential to be readily implemented into clinical practice given that it can be performed fast and on-site. Funding Acknowledgement Type of funding sources: None.

Diagnostic accuracy of instantaneous wave-free ratio at rest and during dobutamine provocation to assess myocardial bridging relevance

Abstract Background Diastolic fractional flow reserve (d-FFR) during dobutamine provocation (DOB) was found to be a more reliable physiological index for the functional assessment of myocardial bridging (MB). However, d-FFR calculation is complicated and time-consuming, and therefore several authors have suggested the use of instantaneous wave-free ratio (iFR) to overcome these issues. Purpose The aim of our study was to assess diagnostic performance of d-FFR and iFR at rest and during DOB with exercise-induced myocardial ischemia as reference. Methods Twenty-four symptomatic patients (17 males, mean age 58±8 years) with MB and systolic compression ≥50% diameter stenosis on the left anterior descending (LAD) artery were included. Exercise stress-echocardiography test (SE), and both d-FFR and iFR in the distal segment of LAD at rest and peak DOB (30–50μg/kg/min), were performed in all patients. Optimal cut-off values and diagnostic performance of resting and hyperemic d-FFR and iFR were assessed using SE. Results Exercise-SE was positive for myocardial ischemia in 7/24 patients (29%). The area-under-the-receiver-operating-characteristic curve (ROC-AUC) for exercise-induced myocardial ischemia was 0.64 (95% CI: 0.400–0.885) for resting d-FFR, 0.62 (95% CI: 0.378–0.866) for resting iFR, 1.000 (95% CI: 0.999–1.000) for d-FFR at peak DOB, and 0.96 (95% CI: 0.895–1.000) for iFR at peak DOB. No significant difference in ROC-AUC was observed between d-FFR and iFR at peak DOB (p=0.243). The best cut-off value for both d-FFR and iFR at peak DOB was &amp;lt;0.76 with similar sensitivity and negative predictive values (100 vs. 100% for both), but lower specificity and positive predictive value for iFR in identifying MB associated with exercise-induced ischemia (94% vs. 82%; 88% vs. 70%, respectively). Compared with exercise-induced myocardial ischemia, the diagnostic accuracy of d-FFR and iFR at peak DOB was 96% (kappa=0.903, p&amp;lt;0.001) and 88% (kappa=0.731, p&amp;lt;0.001), respectively. Conclusions iFR during DOB provocation showed similar diagnostic accuracy as d-FFR to identify the functionally significant MB when compared with exercise-induced myocardial ischemia. Funding Acknowledgement Type of funding sources: None.