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.

IN PATIENTS WITH HYPERTENSIVE LEFT VENTRICULAR HYPERTROPHY AND CORONARY HEART DISEASE,CORONARY FLOW RESERVE IS SIMILARLY IMPAIRED

Coronary blood flow reserve (CFR) was assessed by transesophageal Doppler echocardiography in normal subjects (group A. n=20),hypertensive non-left ventricular hypertrophy (non-LVH)Patients (group B,n=22). hypertensive patients with LVH(group C.n=32)and coronary heart disease patients (group D. n=33) with the volume sample placed at the bifurcation of the left main and left main and left descending coronary artery. Coronary blood flow velocity (CBFV)was evaluated at rest.2 minutes after dipyridamole (0. 56mg/kg. i. v.) . and 2 minutes after aminophylline i.v. The ratio of dipyridamole to rest maximal diastolic velocity (D/R PDV) was considered the index of coronary blood flow reserve.It was found that D/R PDV was significantly less in groups C and D compared with that in groups A and B (D PDC,1.84±0. 57. 1. 57±0. 41 versus 2.59±0.70 and 2.22+0.58,respectively),with no difference in D/R PDV between groups C and D.Twenty-four out of 32 patients in group C with D/R PDV were less than 2.0 compared to 29 out of 33 patients in group D (P>0.05).Significant negative correlation was found between D/R PDV. D/R PSV and interseptal thickness. left ventricular mass index in hypertensive patients.These data show that impaired CFR in hypertensive patients with LVH is comparable to that in patients with coronary heart disease.

Quantitative Assessment of Coronary Flow Reserve by the Variables of Time-Intensity Curve with Myocardial Contrast Echocardiography

The reliability and reliable indexes of q ua ntitative assessment of coronary flow reserve (CFR) by using time intensity cur ve (TIC) via myocardial contrast echocardiography were investigated. The TIC var iables were obtained by employing acoustic densitometry (AD) technique before an d after acetylcholine (Ach) injection in 12 dogs. Meanwhile, the correlation be tween these variables and CFR was analyzed. Among the variables derived from TIC , peak intensity (PI), area under the curve (AUC) and descending slope (DS) were increased significantly ( P <0.05) with the increase of coronary blood flow a fter Ach injection. Conversely, time to peak (TP), half time of descent (HT) , and mean transit time (MTT) were decreased remarkably ( P <0.0001). Th e P I and AUC ratios from post to pre Ach injection were strongly associated with CFR with the correlation coefficient (r) being 0.8366 and 0.8824, respectively. It is reliable by using the variables derived from TIC with myocardial contrast echocardiography to quantitatively evaluate regional myocardial CFR. The PI an d AUC ratios from post to pre Ach injection are the reliable indexes for quan titative assessment of CFR.

Usefulness of coronary flow reserve measured by transthoracic coronary Doppler ultrasound in the elderly

The left anterior descending （LAD） coronary artery is the main vessel of human coronary circulation, and life-threa- tening consequences are seen when flow in this area is im- paired, Noninvasive measurement of coronary flow re- serve （CFR）, defined as the ratio of maximal to baseline coronary blood flow, has been repeatedly shown to be a feasible technique by ultrasound transthoracic Doppler （TTD） both in the LAD and, with some limitations, in the posterior descending （PD） coronary artery.

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 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.

Impact of uncontrolled blood pressure on diagnostic accuracy of coronary flow reserve for detecting significant coronary stenosis in hypertensive patients

Background Impaired coronary flow reserve （CFR） in patients with hypertension may be caused by epicardial coronary stenosis or microvascular dysfunction. Antihypertensive treatment has been shown to improve coronary microvascular dysfunction. The aim of this study was to evaluate the impact of uncontrolled blood pressure （BP） on diagnostic accuracy of CFR for detecting significant coronary stenosis. Methods A total of 98 hypertensive patients scheduled for coronary angiography （CAG） due to chest pain were studied. Of them, 45 patients had uncontrolled BP （defined as the office BP 〉140/90 mmHg （1 mmHg=0.133 kPa） in general hypertensive patients, or ≥130/80 mmHg in hypertensive individuals with diabetes mellitus）, and the remaining 53 patients had well-controlled BP. CFR was measured in the left anterior descending coronary artery （LAD） during adenosine triphosphate-induced hyperemia by non-invasive transthoracic Doppler echocardiography （TTDE） within 48 hours prior to CAG. Significant LAD stenosis was defined as 〉70% luminal narrowing. Diagnostic accuracy of CFR for detecting significant coronary stenosis was analyzed with a receiver operating characteristic analysis. Results CFR was significantly lower in patients with uncontrolled BP than in those with well-controlled BP （2.1±0.6 vs. 2.6±0.9, P〈0.01）. Multivariate linear regression analysis of the study showed that the value of CFR was independently associated with the angiographically determined degree of LAD stenosis （β= -0.445, P 〈0.0001） and the presence of uncontrolled BP （β= -0.272, P=0.014）. With a receiver operating characteristic analysis, CFR 〈2.2 was the optimal cut-off value for detecting LAD stenosis in all hypertensive patients （AUC 0.83, 95% CI 0.75-0.91） with a sensitivity of 75%, a specificity of 78%, and an accuracy of 77%. A significant reduction of diagnostic specificity was observed in patients with uncontrolled BP compared with those with well-controlled BP （67% vs. 93%, P=0.031）. Conclusions CFR measurement by TTDE is valuable in the diagnosis of significant coronary stenosis in hypertensive patients. However, the diagnostic specificity is reduced in patients with uncontrolled BP.

Clinical Relevance of Coronary Fractional Flow Reserve： Art-of-state

Objective：The objective was to delineate the current knowledge of fractional flow reserve （FFR） in terms of definition,features,clinical applications,and pitfalls of measurement of FFR.Data Sources：We searched database for primary studies published in English.The database of National Library of Medicine （NLM）,MEDLINE,and PubMed up to July 2014 was used to conduct a search using the keyword term ＂FFR＂.Study Selection：The articles about the definition,features,clinical application,and pitfalls of measurement of FFR were identified,retrieved,and reviewed.Results：Coronary pressure-derived FFR rapidly assesses the hemodynamic significance of individual coronary artery lesions and can readily be performed in the catheterization laboratory.The use of FFR has been shown to effectively guide coronary revascularization procedures leading to improved patient outcomes.Conclusions：FFR is a valuable tool to determine the functional significance of coronary stenosis.It combines physiological and anatomical information,and can be followed immediately by percutaneous coronary intervention （PCI） if necessary.The technique of FFR measurement can be performed easily,rapidly,and safely in the catheterization laboratory.By systematic use of FFR in dubious stenosis and multi-vessel disease,PCI can be made an even more effective and better treatment than it is currently.The current clinical evidence for FFR should encourage cardiologists to use this tool in the catheterization laboratory.

Noninvasive assessment of renal fractional flow reserve： are we there yet？

The highly diagnostic performance of renal transstenotic pressure gradients （TSPG） and fractional flow reserve （FFR） has been well validated for assessment of the hemodynamic renal artery stenosis （RAS）.1-4 Accordingly,an expert consensus panel of the American Heart Association recommended that a peak systolic gradient of at least 20 mmHg （1 mmHg=0.133 kPa）,or a mean pressure gradient of 10 mmHg,be used to identify candidate lesions for revascularization in symptomatic patients with RAS.

Noninvasive Measurement of Coronary Fractional Flow Reserve： An Under-exploiting Newland

INTRODUCTION In patients with coronary artery disease （CAD）, the most important factors regarding to both symptoms and outcomes are the presence and extent of inducible ischemia. Alleviation of ischemia with percutaneous coronary intervention （PCI） can improve symptoms and clinical outcomes.

Fractional Flow Reserve： From Homeland to Colony

In current catheter research, there are 3 main directions with respect to fractional flow reserve （FFR）, including instantaneous wave-tree ratio, noninvasive measurement of FFR, and FFR transferred from coronary circulation to other ischemia-inducing circulation. Recently, an interesting study was published, in which FFR was performed to diagnose and guide stenting in chronic mesenteric ischemia （CMI）. We herein highlighted, the implications and limitations of FFR from coronary artery to renal artery and mesenteric artery for future investigations, respectively.

Effects of hypoxia on coronary flow reserve as determined by myocardial contrast echocardiography in swine

Background Time-intensity curves derived from microbubble destruction/refilling sequences and recorded using myocardial contrast echocardiography (MCE) can provide parameters that correlate with coronary blood flow. The response of these parameters to adenosine vasodilatation correlates with coronary flow reserve (CFR) measured by fluorescent microsphere techniques (FMT). Currently, no data exist regarding the effect of physiological variables, such as hypoxia, on the determination of CFR by MCE. The purpose of this study was to define the effects of decreases in blood partial pressure of oxygen (PO_2) on CFR as measured by MCE. Methods Studies were performed in 9 closed chest swine. Low-energy, real-time MCE was performed with commercial instruments in short axis view at papillary muscle level while infusing BR_1 at 30 ml/h. High-energy ultrasound bursts (referred to as FLASH frames) destroyed the bubbles every 15 cardiac cycles, and resultant time-intensity curves derived from these sequences were fitted to the exponential function y = A (1-e -bt) +c, from which the rate of signal rise (b) was obtained. CFR was calculated as the ratio of b values after adenosine infusion to baseline and was obtained during the control period and after decreasing blood PO_2 by giving nitrogen via a respirator to create artificial hypoxic conditions. CFR was independently determined by FMT. Results Nitrogen led to significant decreases in mean PO_2, from (120.6±18.9) mmHg to (51.8±15.9) mmHg (P<0.01). Adenosine produced a similar increase in CFR (2.5 fold vs 3.1 fold) as assessed by MCE and FMT during the control period. The decrease in PO_2 post nitrogen resulted in a slight increase in values at rest: 0.46±0.15 to 0.53±0.18 for b and (1.39±0.66) ml·min -1·g -1 to (1.72±0.30) ml·min -1·g -1 for myocardial blood flow (MBF) (both P<0.05). In addition, values decreased in response to adenosine using both techniques: 1.05±0.35 to 0.82±0.27 for b and (4.30±3.16) ml·min -1·g -1 to (3.93±1.27) ml·min -1·g -1 for MBF (both P<0.05). Thus, CFR was markedly reduced under hypoxic conditions, to 1.4 by MCE (P<0.05 compared with the baseline), and to 2.5 by FMT (P>05 compared with the baseline). Conclusions CFR values diminish under hypoxic conditions according to both MCE and FMT. The reductions in CFR involve both an increase in resting values and a decrease in post adenosine measurements, as determined by both techniques. The reduction in CFR under hypoxia is slightly greater using MCE than using FMT. Physiological variables, such as hypoxia, must be taken into consideration when assessing CFR by MCE.

Role of fractional flow reserve in guiding intervention for borderline coronary lesions

Objective:This study investigated the clinical efficacy and value of fractional flow reserve(FFR)in guiding the treatment of borderline coronary lesions.Methods:Forty-three patients with borderline coronary lesions,as demonstrated by coronary angiography,and who had FFR measurements were selected.The patients were grouped accord-ing to FFR values.All patients were evaluated 6 months after surgery to record major adverse cardiac events(MACE[sudden cardiac death,non-fatal myocardial infarction,or revasculariza-tion])and recurrence of angina pectoris.Results:After the 6-month follow-up,no sudden cardiac deaths or myocardial infarctions occurred in either group,and there were no statistically significant differences(P>0.05).Inter-group comparisons showed that in the groups with a FFR<0.75,the recurrence rate of angina pectoris in the PCI group was significantly lower than the drug therapy group(0.08%vs.0.27%,P<0.05).In contrast,the recurrence rate of angina pectoris in the PCI group among the groups with a FFR<0.75 revealed no statistical significance when compared to the groups with a FFR≥0.75(0.08%vs.0.05%,P>0.05).The recurrence rate of angina pectoris in the simple drug therapy group among the groups with a FFR<0.75 was higher than the same groups with a FFR≥0.75(0.27%vs.0.05%,P<0.05).Conclusion:When coronary intervention is used to treat borderline lesions,guiding inter-ventional therapy with measurement of FFR does not increase the incidence of adverse cardiovas-cular events in the short term and can better guide PCI therapy.