Non-invasive Angiographic-based Fractional Flow Reserve:Technical Development,Clinical Implications,and Future Perspectives

New non-and less-invasive techniques have been developed to overcome the procedural and operator related burden of the fractional flow reserve(FFR)for the assessment of potentially significant stenosis in the coronary arteries.Virtual FFR-techniques can obviate the need for the additional flow or pressure wires as used for FFR measurements.This review provides an overview of the developments and validation of the virtual FFR-algorithms,states the challenges,discusses the upcoming clinical trials,and postulates the future role of virtual FFR in the clinical practice.

Fractional flow reserve measured via left internal mammary artery after coronary artery bypass grafting:Two case reports

BACKGROUND The fractional flow reserve(FFR)has made the treatment of coronary heart disease more precise.However,there are few reports on the measurement of FFR via the left internal mammary artery(LIMA).Herein,we described the determination of further treatments by measuring FFR via the LIMA in 2 cases after coronary artery bypass grafting(CABG).CASE SUMMARY Case 1 was a 66-year-old male who was admitted due to“chest tightness after CABG.”The patient underwent CABG 7 years prior due to coronary heart disease.Coronary artery angiography showed complete occlusion of the left anterior descending artery(LAD),and subtotal occlusion of the third segment of the right coronary artery.On arterial angiography,there was 85%stenosis at the distal end of the anastomosis of the LIMA-LAD graft.FFR via LIMA was determined at 0.75.Thus,balloon dilation was performed in Case 1.FFR after balloon dilation was 0.94.Case 2 was a 60-year-old male who was admitted due to“chest tightness after CABG.”The patient underwent CABG 6 years prior due to coronary heart disease.There was 60%segmental stenosis in the middle segment of LAD and 75%anastomotic stenosis.FFR measured via LIMA was 0.83(negative);thus the intervention was not performed.Case 2 was given drug treatments.At the 3-mo follow-up,there was no recurrence of chest tightness or shortness of breath in both cases.They are currently under continual follow-up.CONCLUSION We provided evidence that FFR measurement via grafted blood vessels,especially LIMA,after CABG is a good method to determine the intervention course.

Fractional flow reserve and non-hyperemic indices:Essential tools for percutaneous coronary interventions

Hemodynamical evaluation of a coronary artery lesion is an important diagnostic step to assess its functional impact.Fractional flow reserve(FFR)received a class IA recommendation from the European Society of Cardiology for the assessment of angiographically moderate stenosis.FFR evaluation of coronary artery disease offers improvement of the therapeutic strategy,deferring unnecessary procedures for lesions with a FFR>0.8,improving patients'management and clinical outcome.Post intervention,an optimal FFR>0.9 post stenting should be reached and>0.8 post drug eluting balloons.Non-hyperemic pressure ratio measurements have been validated in previous studies with a common threshold of 0.89.They might overestimate the hemodynamic significance of some lesions but remain useful whenever hyperemic agents are contraindicated.FFR remains the gold standard reference for invasive assessment of ischemia.We illustrate this review with two cases introducing the possibility to estimate also non-invasively FFR from reconstructed 3-D angiograms by quantitative flow ratio.We conclude introducing a hybrid approach to intermediate lesions(DFR 0.85-0.95)potentially maximizing clinical decision from all measurements.

Clinical applications of fractional flow reserve in bifurcation lesions

Pereutaneous coronary intervention （PCI） for coronary bifurcation lesions has been associated with lower procedural success rates and worse clinical outcomes compared with PCI for simple coronary lesions. Angiographic evaluation alone is sometimes inaccurate and does not reflect the fimctional significance of bifurcation lesions. The fractional flow reserve （FFR） is an easily obtainable, reliable, and reproducible physiologic parameter. This parameter is epicardial lesion specific and reflects both degree of stenosis and the myocardial territory supplied by the specific artery. Recent studies have shown that FFR-guided provisional side branch intervention strategy for bifurcation lesions is feasible and effective and can reduce unnecessary complex interventions and related complications. However, an adequate understanding of coronary physiology and the pitfalls of FFR is essential to properly use FFR for PCI of complex bifurcation lesions.

Heart and skeletal muscle insulin resistance but not myocardial blood flow reserve could be related to chronic use of thiazolidione in patients with type-2 diabetes

Heart and skeletal muscle insulin resistance and abnormal myocardial flow reserve (MFR) occurs in patients with type-II diabetes. Improvement of heart and skeletal muscle insulin resistance with rosiglitazone use over 16 weeks have been reported. However, it is not clear whether chronic use of troglitazone can improve heart and skeletal muscle insulin resistance and MFR. Materials and Methods: To test the hypothesis whether effects of troglitazone on heart and skeletal muscle insulin resistance and MFR in patients with type-II diabetes, rest and dipyridamole stress perfusion positron emission tomography (PET) with 13N-ammonia and heart and skeletal muscle 18FDG PET scans under insulin clamping were undertaken before and 12 month after the initiation of troglitazone therapy (400 mg/day) in 23 patients with type-II diabetes. Twenty patients with type-II diabetes without CAD and without medications were served as controls. In controls, any medications were not added from the first PET study and 12 months after the second PET study. Results: Baseline myocardial blood flow (MBF) was comparable before and after the troglitazone group as was the controls. MBF during dipyridamole administration (0.56 mg/min/kg) was not significantly improved in troglitazone group and controls. MFR was not improved in troglitazone group and controls. In troglitazone group, whole body glucose disposal rate (GDR;μmole/min/kg) significantly improved (pre;19.0 ± 9.55, post;28.7 ± 15.3, p as did the skeletal muscle glucose utilization rate (SMGU (μmole/min/kg);pre;20.3 ± 12.0, post;34.8 ± 10.6, p insulin resistance is implicated in patients with type-II diabetes and impaired MFR is uncoupled with insulin resistance in the whole body and heart and skeletal muscle in patients with type-II diabetes.

Comparative efficacy and safety of adenosine and regadenoson for assessment of fractional flow reserve:A systematic review and meta-analysis

BACKGROUND Adenosine is a coronary hyperemic agent used to measure invasive fractional flow reserve(FFR)of intermediate severity coronary stenosis.AIM To compare FFR assessment using adenosine with an alternate hyperemic agent,regadenoson.METHODS PubMed,Google Scholar,CINAHL and Cochrane databases were queried for studies comparing adenosine and regadenoson for assessment of FFR.Data on FFR,correlation coefficient and adverse events from the selected studies were extracted and analyzed by means of random effects model.Two tailed P-value less than 0.05 was considered significant.Heterogeneity was assessed using I2 test.RESULTS Five studies with 248 patients were included in the final analysis.All included patients and coronary lesions underwent FFR assessment using both adenosine and regadenoson.There was no significant mean difference between FFR measurement by the two agents[odds ratio(OR)=-0.00;95%confidence interval(CI):(-0.02)-0.01,P=0.88].The cumulative correlation coefficient was 0.98(0.96-0.99,P<0.01).Three of five studies reported time to FFR with cumulative results favoring regadenoson(mean difference 34.31 s;25.14-43.48 s,P<0.01).Risk of adverse events was higher with adenosine compared to regadenoson(OR=2.39;95%CI:1.22-4.67,P=0.01),which most commonly included bradycardia and hypotension.Vast majority of the adverse events associated with both agents were transient.CONCLUSION The performance of regadenoson in inducing maximal hyperemia was comparable to that of adenosine.There was excellent correlation between the FFR measurements by both the agents.The use of adenosine,was however associated with higher risk of adverse events and longer time to FFR compared to regadenoson.

Modes of failure with fractional flow reserve guidewires:Insights from the manufacturer and user facility device experience database

BACKGROUND Fractional flow reserve(FFR)measurement is commonly used in the cardiac catheterization laboratory to assess the functional significance of coronary arterial plaques.Robust real-world data on complications and modes of failure of FFR guidewires are limited.AIM To characterize these outcomes by analyzing the post-marketing surveillance data from the United States Food and Drug Administration Manufacturer and User Facility Device Experience(MAUDE)database for commonly used FFR guidewires.METHODS The MAUDE database was queried from January 2010 through April 2020 for 3 FFR guidewires[PressureWireTM X(Abbott),CometTM(Boston Scientific),and VerrataTM(Philips)]by searching for the following events:“Injury”,“malfunction”,“death”,and“other”.This yielded 544 reports.After excluding incomplete reports,486 reports were analyzed.RESULTS Guidewire tip fracture was the most commonly reported mode of failure,in 174(35.8%)cases followed by guidewire kinking(n=152,31.3%),communication failure(n=141,29.0%),and shaft fracture(n=67,13.8%).In total,133(27.4%)device failures resulted in patient adverse events.The most common adverse event was retained guidewire tip,in 71(53.4%)cases,followed by freshly deployed stent dislodgment(n=26,19.6%)and coronary artery dissection(n=23,17.3%).Seven deaths were reported.CONCLUSION FFR guidewire failures can occur because of various mechanisms and cause patient adverse events.The MAUDE database serves as an important platform for improved collaboration among clinicians,device manufacturers,and regulators to improve device performance and optimize patient outcomes.Our analysis provides mechanistic insights of FFR guidewire failure and associated adverse events but cannot verify causality or provide a comparison among different guidewires.

Usefulness of Fractional Flow Reserve during Routine Clinical Procedures in All-Comer Coronary Artery Disease Patients

Background: Fractional flow reserve (FFR)-guided interventions, though proved to be safe, continue to be a much-underutilized modality in determining treatment strategy, and data is lacking in Indian population. Objective: We aimed to determine the use of FFR-guided PCI and assess the overall impact on treatment decisions and clinical outcomes in patients with acute coronary syndrome (ACS) or chronic coronary syndromes (CCS). Methods: In this single-center retrospective and prospective observational study, FFR had been performed for the evaluation of treatment reclassification and clinical outcomes, as per physician’s clinical practice. Results: Data was obtained for 250 subjects (mean age 60.45 ± 9.6 years) with 324 lesions. The treatment plan based on angiography alone changed in 28% of lesions post-hyperemic FFR. The initial treatment plan based on angiography vs. the final treatment plan post-FFR (>0.80) was medical management 56.5% vs. 66.0%;CABG 11.1% vs. 7.7%;and PCI 32.4% vs. 26.2%. In subjects initially assigned to medical management, 14% had changed to PCI, and for subjects initially assigned to PCI, 44% had changed to medical therapy. Receiver operating characteristics (ROC) curve analysis revealed a good correlation between a resting FFR value of <0.87 and hyperemic FFR value of <0.80. The rate of 2-year major adverse cardiovascular events (MACE) was 0.9%. Conclusion: This study supports the use of FFR in determining treatment strategy in ACS or CCS patients with low MACE. Resting FFR value of <0.87 may be an alternative to intracoronary nitroglycerine/adenosine/Nikorandil-induced FFR in predicting positive FFR particularly in hemodynamically unstable patients, and who are intolerant to hyperemic drugs.

Fractional flow reserve: Current applications and overview of the available data

Flow fractional reserve(FFR) allows to evaluate the functional significance of coronary artery lesions, through the ratio of the mean coronary artery pressure after the stenosis to the mean aortic pressure duringmaximum hyperemia. The actual widely accepted cutoff value is 0.80. Below this value a coronary lesion is considered significant and therefore it requires invasive revascularization. Several studies [in particular Fractional Flow Reserve vs Angiography for Multivessel Evaluation 1(FAME-1) and FAME-2] have shown the relationship between FFR measurement and hard end-points(death, myocardial infarction, and urgent revascularization). Consequently, FFR evaluation represents the cornerstone in the decision-making in intermediate coronary lesions. Recent studies paved the way for further applications of FFR evaluation in complex and tricky clinical settings. In this paper, we perform an overview of the data regarding contemporary application of FFR. In particular, we review the use of FFR in: left main intermediate stenoses, serial stenoses, evaluation after stenting, guidance in coronary artery bypass surgery, and acute coronary syndrome. All the data presented in our overview confirm the essential role of FFR assessment in the daily clinical practice. The shift from "operator-dependent" to "FFR-dependent" evaluation in intermediate coronary artery stenosis is of paramount importance in order to improve the prognosis of our patients, through the discrimination of the functional role of every single coronary stenosis.

Long-term outcomes after fractional flow reserve-guided percutaneous coronary intervention in patients with severe coronary stenosis

Objective To explore the safety and efficacy of FFR-guided percutaneous coronary intervention (PCI) in vessels with severe diameter stenosis. Methods & Results Of 1090 patients undergoing fractional flow reserve (FFR) assessment from 2002 to 2009,we identified 167 patients in whom FFR was measured in at least one 70%–89% stenotic lesion. These patients were subdivided into an FFR-defer group (n = 49) if PCI was deferred (FFR > 0.80),and an FFR-perform group (n = 118) if PCI was performed (FFR ≤ 0.80). Comparatively,an additional 1176 patients undergoing PCI in at least one lesion with 70%–89% stenosis but without measurement of FFR served as a control (angiography- guided) group. Clinical outcomes were compared during a median follow-up of 49.0 months. The 5-year Kaplan-Meier estimated revascularization rates were 16% in the FFR-defer group and 33% in the FFR-perform group (P = 0.046). The incidence of major adverse cardiac events were comparable in these two groups (HR = 0.82,95% CI: 0.37–1.82,P = 0.63). The number of stents placed was significantly lower in the FFR-guided group (0.9 ± 0.8 vs. 1.4 ± 0.8,P < 0.001). Conclusions Functional revascularization for lesions with visually severe stenosis is clinically safe and associated with fewer stents use. This study suggests that extending the use of FFR to more severe coronary lesions may be reasonable.

A Fast-Fractional Flow Reserve Simulation Method in A Patient with Coronary Stenosis Based on Resistance Boundary Conditions

Fractional flow reserve(FFR)is the gold standard to identify individual stenosis causing myocardial ischemia in catheter laboratory.The purpose of this study is to present a fast simulation method to estimate FFR value of a coronary artery,which can evaluate the performance of vascular stenosis,based on resistance boundary conditions.A patient-specific 3-dimensional(3D)model of the left coronary system with intermediate diameter stenosis was reconstructed based on the CTA images.The resistance boundary conditions used to simulate the coronary microcirculation were computed based on anatomical reconstruction of coronary 3D model.This study was performed by coupling the 3D coronary tree model with the lumped parameter model(0D model).The flow rate and pressure of coronary tree were calculated in twenty minutes.In addition,the effect of inlet pressure and myocardial mass on FFRss values has been investigated.The results showed that the effect of myocardial mass was greater than the effect of inlet pressure on FFRss.This FFRss simulation method can quickly and accurately assess the influence of coronary stenosis in aid clinical diagnosis.

Fractional Flow Reserve Measurement by Coronary Computed Tomography Angiography:A Review with Future Directions

Invasive fractional fl ow reserve(FFR)measurement is currently the gold standard for coronary intervention.FFR measurement by coronary computed tomography angiography(FFRCT)is a novel and promising imaging technology that permits noninvasive assessment of physiologically signifi cant coronary lesions.FFRCT is capable of combining the anatomic information provided by coronary computed tomography angiography with computational fl uid dynamics to compute FFR.To date,several studies have reported the diagnostic performance of FFRCT compared with invasive FFR measurement as the reference standard.Further studies are now being implemented to determine the clinical feasibility and economic implications of FFRCT techniques.This article provides an overview and discusses the available evidence as well as potential future directions of FFRCT.

Fractional Flow Reserve-guided Percutaneous Coronary Intervention:Standing the Test of Time

Percutaneous coronary intervention(PCI)improves symptoms and prognosis in ischemia-inducing,functionally signifi cant,coronary lesions.Use of fractional flow reserve allows physicians to investigate the ischemia-inducing potential of a specifi c lesion and can be used to guide coronary revascularization,especially in multivessel coronary artery disease.Fractional flow reserve-guided PCI has been extensively investigated.Results show that deferral of stenting in non-signifi cant lesions is safe,whereas deferral of stenting in functionally signifi cant lesions worsens outcome.FFR-guided PCI improves outcome in multivessel disease over angiography-guided PCI.Until recently,there was little known about the long-term outcome of FFR-guided revascularization and its validity in acute coronary syndromes.This review aims to address the new evidence regarding long-term appropriateness of FFR-guided PCI,the need for hyperemia to evaluate functional severity,and the use of FFR in acute coronary syndromes.

Comparison of Fractional Flow Reserve-Guided Revascularization Strategies in Isolated Proximal Left Anterior Descending Coronary Artery Disease

The data about FFR-guided revascularization in isolated proximal LAD disease are limited and studies comparing long-term outcomes of FFR-guided PCI versus FFR-guided CABG in single-vessel proximal LAD disease are lacking. We aimed to assess the 4-year long-term safety and effectiveness of fractional flow reserve (FFR)-guided percutaneous coronary intervention (PCI) and FFR-guided coronary artery bypass graft surgery (CABG) for the treatment of proximal left anterior descending (LAD) lesions. The study included 129 patients with functionally significant (FFR ≤ 0.80) isolated proximal LAD stenosis (PCI, 88 patients vs. CABG, 41). Clinical endpoints were assessed by Kaplan-Meier method and compared by the log-rank test. At a mean follow-up time of 47 ± 12 months, a higher incidence of myocardial infarction in the PCI group (PCI: 32% vs. CABG: 15%;p = 0.003) and a higher incidence of stroke in the CABG group (CABG: 3 (7%) vs. PCI 0 (0%);p = 0.031) were observed. However, there were no significant differences in the primary composite endpoint, death and target vessel revascularization between PCI and CABG groups. The PCI and CABG in isolated proximal LAD lesions yielded similar long-term outcomes regarding the primary composite clinical endpoints. However, stroke was more frequent in the CABG group than in the PCI group.

Myocardial ischemia is a key factor in the management of stable coronary artery disease

Previous studies demonstrated that coronary revascularization,especially percutaneous coronary intervention(PCI),does not significantly decrease the incidence of cardiac death or myocardial infarction in patients with stable coronary artery disease.Many studies using myocardial perfusion imaging(MPI) showed that,for patients with moderate to severe ischemia,revascularization is the preferred therapy for survival benefit,whereas for patients with no to mild ischemia,medical therapy is the main choice,and revascularization is associated with increased mortality.There is some evidence that revascularization in patients with no or mild ischemia is likely to result in worsened ischemia,which is associated with increased mortality.Studies using fractional flow reserve(FFR) demonstrate that ischemia-guided PCI is superior to angiography-guided PCI,and the presence of ischemia is the key to decisionmaking for PCI.Complementary use of noninvasive MPI and invasive FFR would be important to compensate for each method's limitations.Recent studies of appropriateness criteria showed that,although PCI in the acute setting and coronary bypass surgery are properly performed in most patients,PCI in the non-acute set-ting is often inappropriate,and stress testing to identify myocardial ischemia is performed in less than half of patients.Also,some studies suggested that revascularization in an inappropriate setting is not associated with improved prognosis.Taken together,the presence and the extent of myocardial ischemia is a key factor in the management of patients with stable coronary artery disease,and coronary revascularization in the absence of myocardial ischemia is associated with worsened prognosis.

Case of angina pectoris at rest and during effort due to coronary spasm and myocardial bridging

We present a case of a 71-year-old male who hadchest symptoms at rest and during effort. He had felt chest oppression during effort for 1 year,and his chest symptoms had recently worsened. One month before admission he felt chest squeezing at rest in the early morning. He presented at our institution to evaluate his chest symptoms. Electrocardiography and echocardiography failed to show any specific changes. Because of the possibility that his chest symptoms were due to myocardial ischemia,he was admitted to our institution for coronary angiography(CAG). An initial CAG showed mild atherosclerotic changes in the proximal segment of the left anterior descending coronary artery(LAD) and mid-segment of the left circumflex coronary artery. Subsequent spasm provocation testing using acetylcholine revealed a bilateral coronary vasospasm,which was relieved after the intracoronary infusion of nitroglycerin. Finally,a CAG showed myocardial bridging(MB) of the mid-distal segments of the LAD. Fractional flow reserve using the intravenous administration of adenosine triphosphate was positive at 0.77,which jumped up to 0.90 through the myocardial bridging segments when the pressure wire was pulled back. Thus,coronary vasospasm and MB might have contributed to his chest symptoms at rest and during effort. Interventional cardiologists should consider the presence of MB as a potential cause of myocardial ischemia.

Evaluation of myocardial infarction patients after coronary revasculation by dual-phase multi-detector computed tomography:Now and in future

Multidetector-row computed tomography(MDCT) has become one of the major tools in diagnosing and evaluating patients with coronary artery disease in recent years.In selected patients,MDCT has been shown to provide more reliable accuracy in detection of stent patency than invasive coronary angiography.Chiou et al reported a delicate infarcted myocardium at-risk score.According to their results,the MDCT-based myocardium at-risk score had a good correlation with the thallium 201 ST-segment elevation myocardial infarction-based summed difference score(r = 0.841,P < 0.001).They claimed that dual-phase MDCT is useful in detecting different patterns of obstructive lesions and the extent of myocardium at risk.In this commentary,we discuss the current status of the clinical application of MDCT in patients with myocardial infarction in relation to evaluating the myocardial perfusion defect,detecting reversible myocardial ischemia,assessing myocardial viability,estimating target lesion restenosis,and calculating of fractional flow reserve from MDCT.

Fractional Flow Reserve Guided Percutaneous Coronary ntervention Improves Clinical Outcome with Reduced Cost in Contemporary Clinical Practice

Background：Fractional flow reserve （FFR） is currently considered as the gold standard for evaluating the functional significance of coronary stenosis.However,its potential benefits in real-world practice remain unknown in China.This study aimed to test the hypothesis that the use of FFR is associated with improved outcome and reduced cost in Chinese real-world clinical practice.Methods：A retrospective cohort study was carried out using the database of Second Affiliated Hospital of Zhejiang University,a tertiary and high-volume center in China.Clinical events were compared using the Cox proportional hazards model during a median follow-up of 13 months.Results：The study cohort consisted of 366 consecutive patients referred for coronary revascularization with adjunct FFR and 366 matched controls,from 2010 to 2014.Major adverse cardiac events （MACEs） （death,myocardial infarction,repeated revascularization,or hospitalization for angina） at 4 years were found in 12.0% ofangiography-guided patients and 4.9% in the FFR-guided group （P 〈 0.001）.The mean number of implanted stents was significantly lower in FFR treated subjects （0.52 ± 0.82 stents） compared with the angiography-guided group （0.93 ± 0.96 stents） （P 〈 0.001）.No difference in overall costs at initial hospitalization was observed between angiography-guided percutaneous coronary intervention （PCI） compared with FFR-guided PCI （RMB 33,000 Yuan,range：RMB 7393-44,700 Yuan） versus RMB 21,200 Yuan （RMB 19,100-47,100 Yuan） （P =0.54）.However,costs for MACEs during follow-up were significantly reduced in the FFR-guided arm （P 〈 0.001）.Conclusions：In the contemporary clinical practice,FFR-guided PCI is associated with decreased use of stents,improved clinical outcome,and reduced costs,compared with angiography-guided PCI.

Hemodynamic changes of fractional flow reserve after double kissing crush and provisional stenting technique for true bifurcation lesions

Background Fractional flow reserve （FFR）-guided percutaneous coronary intervention （PCI） is associated with fewer unfavorable events. However, the hemodynamic change in FFR after different stenting approaches for bifurcation lesions is still not fully studied. The aim of this study was to analyze the hemodynamic changes in FFR after double kissing （DK） crush and provisional side branch （SB） stenting （PS） for true coronary bifurcation lesions. Methods Seventy-five patients with true bifurcated lesions were randomly divided into DK （n=38） and PS （n=37） groups. Additional SB stenting in the PS group was required if there was any pinched SB ostium 〉70% stenosis, or ≥ type B dissection, or TIMI flow 〈grade 3. FFR at hyperemia in the main vessel （MV） and SB was measured prior- and post-stenting, and at 8 months follow-up. Results Baseline clinical, angiographic and lesion characteristics were matched well between the two groups, with the exception of the final kissing balloon inflation （FKBI, 100.0% in the DK vs. 83.8% in the PS group, P 〈0.001）. Baseline FFR was comparable between the DK and the PS groups, however, the acute gain and late loss of SB FFR at 8-month follow-up in the DK group were 0.18±0.15 and -0.06±0.11, compared to 0.12±0.18 （P=0.044） and -0.002±0.07 （P=-0.037） in the PS group, respectively. MV FFR post-stenting 〉0.94 was seen in about 40% of patients. There was no significant difference in the clinical events at 1-year follow-up between the two groups. Conclusions DK crush was associated with improved acute gain and late loss of SB FFR. The lower rate of FFR 〉0.94 after stenting underscored the further improvement of stentinq quality.

Current status of assessment of fractional flow reserve

Coronary angiography presently remains the main method tor the diagnosis and instruction of epicardial coronary disease. However, precise characterization of the significance for any given stenosis is limited by the inability to identify intermediate coronary lesions responsible for ischemia. In clinical practice, in addition to the assessment of the anatomical details of vessel narrowing, a more impediment to coronary precise assessment of the blood flow has become extremely important. At present, several physiological parameters have been introduced to improve discrimination in functional coronary lesion severity during cardiac catheterization. Of these parameters, myocardial fractional flow reserve （FFR） has been the most frequently used and is being increasingly applied to assess the functional significance of intermediate lesions. FFR can provide important information, both for decision making in diagnostic angiography and for monitoring and evaluating coronary interventions.