The present study aimed to compare the clinical outcome of patients with coronary artery disease (CAD) who underwent a revascularization using conventional coronary angiography or a physiologically guided revascularization with Fractional Flow Reserve (FFR). Furthermore, outcomes in FFR guided percutaneous coronary intervention (PCI) and instantaneous wave-free ratio (iFR) guided PCI were compared. The analysis was performed for reported outcomes at a 1-year follow-up. After searching PubMed, EMBASE, and Web of Science for suitable publications, a total of 15,880 subjects were included. Comparing angiography guided and FFR guided PCI showed no significant difference in major adverse cardiac events [odds ratio (OR), 0.78; 95% confidence interval (CI), 0.59–1.04; P=0.09; I2=73%], death from any cause (OR, 0.74; 95% CI, 0.46–1.18; P=0.20; I2=74%), myocardial infarction (OR, 0.93; 95% CI, 0.81–1.07; P=0.31; I2=0%) or unplanned revascularization (OR, 0.71; 95% CI, 0.41–1.23; P=0.22; I2=79%). In addition, no significant difference could be found between iFR and FFR guided PCI for major adverse cardiac events (OR, 0.97; 95% CI; 0.76–1.23; P=0.81; I2=0%), death from any cause (OR, 0.66; 95% CI, 0.40–1.11; P=0.12; I2=0%), myocardial infarction (OR, 0.83; 95% CI, 0.56–1.24; P=0.37) or unplanned revascularization (OR, 1.16; 95% CI, 0.85–1.58; P=0.34; I2=16%). Overall, there was a tendency towards better outcomes of FFR in all four clinical endpoints compared with angiography guiding of PCI, and furthermore iFR showed no significant inferiority when compared to FFR in said clinical endpoints. When conducting a network meta-analysis, the results confirmed a non-inferiority of iFR compared to angiography guided revascularization.
Finding the best course of treatment for coronary artery disease (CAD) is a recurring challenge in everyday clinical practice. Coronary revascularization is only justified for hemodynamically relevant stenosis (
During cardiac catherization, the functional flow reserve (FFR) can be measured as the maximum available blood flow in a stenosed coronary segment. FFR is the current gold standard for deciding if revascularization is required in angiographically ambiguous coronary artery stenosis and is recommended by the 2014 ESC/EACTS guidelines on myocardial revascularization and the 2011 ACCF/AHA/SCAI guidelines for percutaneous coronary intervention (PCI) (
Despite this recommendation and the alleged benefits, the use of FFR is still limited. The administration of vasodilators such as adenosine, which is required to induce maximal hyperaemia when measuring FFR, can cause side effects (i.e. chest pain, dyspnoea, AV-blockage) during the procedure. Those side effects, cost and increased procedural time are preventing FFR from becoming a standard procedure in day-to-day clinical setting.
A rather new method used to determine the severity of a coronary stenosis is the instantaneous wave-free ratio (iFR). By identifying a period of naturally occurring constant peripheral resistance during diastole, there is no need for vasodilators (
Following the described comparable accuracy of FFR and iFR, the goal of this meta-analysis was to compare the clinical outcome of patients with CAD in which the stenosis was either evaluated visually by coronary angiography alone, or by hemodynamic assessment using FFR or iFR.
This meta-analysis was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement and is based on the review of previously published articles (
In July 2017 PubMed, EMBASE, Cochrane Central Register of Controlled Trials (CENTRAL), were searched for studies evaluating the clinical outcomes of FFR and iFR. The keywords were ‘fractional flow reserve’ and ‘myocardial’ or ‘fractional flow reserve’ or ‘wave-free ratio’ or ‘iFR and coronary’ or ‘FFR and coronary’ with no other filter. No language restrictions were applied. We selected studies, which used a comparative analysis to identify a culprit coronary lesion.
The following inclusion criteria were applied. The design was either a randomized clinical trial (RCT) or an observational study comparing either angiography and FFR guided or iFR and FFR guided PCI. Participants were adult (18 years and older) patients with indication for PCI. All data of one-year clinical outcomes (major adverse cardiac event (MACE), death from any cause, myocardial infarction (MI) or unplanned revascularization) could be retrieved from the published full text.
The studies were not conducted on humans (studies on animals or
The following data of eligible studies were documented (
In case the extracted data was appropriate for pooled analysis, a meta-analysis was performed. Dichotomous data was analyzed using the Mantel-Haenszel model and reported as an odds ratio (OR). Forest plots were used for visualization of the results.
The heterogeneity of studies was calculated using the I2 index. An I2 value of 0–25% represents insignificant heterogeneity; >25-50% low heterogeneity; >50-75% moderate heterogeneity; and >75% high heterogeneity (
A total of 756 studies were screened, and nine studies were identified that fulfilled the previously determined inclusion criteria. A flow chart shows the selection process and the reasons for exclusion (
The full-texts of 62 articles were assessed and 53 were not included in the quantitative and qualitative analysis since they did not contain a one-year follow-up or only analyzed a single method of coronary artery lesion evaluation. In total, the remaining studies included 15,880 patients with a one-year follow-up for MACE after PCI. Five studies and 8,403 patients were used for the analysis of angiography guided PCI, seven studies with 5,223 patients were used to analyze the FFR guided PCI and two studies with 2,254 patients were used for analysis of the iFR guided PCI. The exact number of patients for each study can be seen in
Overall, the nine studies did not have significant differences regarding patient baseline characteristics, which can be seen in
All the included studies reported on the outcomes of MACE. After one year the results were OR: 0.78 [95% CI: 0.59–1.04]; P=0.09, I2=73% and were supportive of better outcomes using FFR guided PCI. As for the single components of MACE, data for death from any cause was available in six of the seven studies and found a slight tendency towards FFR guided PCI with OR: 0.74 [95% CI: 0.46–1.18]; P=0.20, I2=74%. Five studies published outcomes for MI and when comparing both methods, the results were OR: 0.93 [95% CI: 0.81–1.07]; P=0.31, I2=0%, but showed no significant difference. Unplanned revascularization was reported in four of the included studies, and they also leaned in favour of FFR guided PCI with an OR: 0.71 [95% CI: 0.41–1.23]; P=0.22, I2=79%. Forest plots for all primary outcomes can be seen in
When excluding the three retrospective studies (
When analyzing the two available studies, there was no significant difference between FFR and iFR regarding MACE with OR: 0.97 [95% CI: 0.76–1.23]; P=0.81. Both studies also reported on the individual components of MACE, and when comparing the two methods in terms of death from any cause (OR: 0.66 [95% CI: 0.40–1.11]; P=0.12, I2=0%), MI OR: 0.83 [95% CI: 0.56–1.24]; P=0.37, I2=0%, and unplanned revascularization (OR: 1.16 [95% CI: 0.85–1.58]; P=0.34, I2=16%), neither reached the level of significance but showed a tendency towards iFR guided revascularization. The forest plots for all primary outcomes are presented in
When conducting a network-analysis to compare angiography and iFR guided revascularization after one-year, the result for MACE was OR: 0.80 [95% CI: 0.55–1.17]; P=0.25. Death from any cause had an OR of: 1.12 [95% CI: 0.56–2.25]; P=0.75 and MI an OR: 1.12 [95% CI: 0.74–1.71]; P=0.60. The results for unplanned revascularization were OR: 0.61 [95% CI: 0.33–1.15]; P=0.13.
This meta-analysis was conducted to analyze the clinical outcomes as described above of studies containing angiography and FFR guided PCI or iFR compared to FFR guided PCI. When comparing FFR and iFR with angiography outcomes, the main finding was a tendency towards FFR/iFR in all 4 clinical endpoints.
With the analysis of MACE having factored in all seven included studies, one could interpret these results to be the most convincing. When looking at the Odds Ratio, a tendency towards FFR becomes clear, and this is supported by the results of the individual components of MACE. Although the I2 of MACE, death from any cause and unplanned revascularization were >50%, we decided not to exclude further studies in order to uphold a larger number of included patients.
FFR was first tested on its usefulness to determine the need for revascularization in intermediate coronary stenosis two decades ago (
In contrast to our findings, a meta-analysis by Enezate
Furthermore, a meta-analysis by Zhang
In addition, not all studies support the findings of the FAME study. The DEFER-DES study, which compared the 5-year outcomes of angiography and FFR guided PCI using drug eluting stents (DES), did not find any superiority for FFR guided DES implantation or routine DES implantation regarding the rate of MACE (11.6±3.0 and 14.2±3.3%, respectively (P=0.55) (
Excluding the retrospective studies from this current analysis prompted a change of results regarding MACE as well. By doing this, the trend moved stronger towards FFR, and the heterogeneity moved from high to low. This may indicate the existence of influencing factors in these three retrospective studies. With more studies being published in the future, in another meta-analysis carried out later one may alter the inclusion criteria and thus reduce the heterogeneity. One way could be to only include prospective RCT's or to exclude any study which had NSTEMI as an indication for PCI such as Layland
Another aspect of our meta-analysis was the difference between iFR guided and FFR guided PCI, since the absence of inferiority of iFR compared to FFR has been shown in the iFR-SWEDHEART (
But, in order to compare angiography and iFR guided revascularization in a more direct way, we also conducted network meta-analysis. Although this network meta-analysis cannot be equated to a direct comparison, one can see that iFR is not inferior to angiography guided revascularization. This result is a very novel aspect of this paper and should be considered when talking about the best procedure when performing PCI.
As described above, iFR achieved similar results in comparison to FFR in similar study conditions. Nevertheless, further investigations should be conducted on iFR by itself in more complex situations, but also in a direct comparison to angiography and other treatment strategies for CAD, such as CABG.
Limitations of this meta-analysis are similar to the limitations of other meta-analyses. This includes the fact that we had no access to primary data, and the accuracy of our analysis depends on the accuracy of the primary sources. This meta-analysis includes prospective randomized controlled trials as well as retrospective non-randomized studies. Furthermore, the threshold for ischemia detection was not defined uniformly between the FFR studies (some studies used 0.75 and others 0.8). Lastly, it should be noted that the sample size of some of the studies was small and the populations for the three interventions all differed in size (angiography guided PCI included 8,403 patients; FFR guided PCI only included 5,223) Furthermore, we could only include two iFR studies in this meta-analysis, since iFR is a relatively new clinical procedure.
Overall, FFR guided PCI showed superiority in MACE during one year of follow up rates when comparing with angiography guided PCI. The high heterogeneity did not remain when excluding three retrospective studies and even reinforced the preference towards FFR. iFR guided PCI also did not show inferiority to FFR guided PCI, and thus one can assume iFR to be superior to solely angiography guided PCI as well. Because low heterogeneity and the small number of available studies limits the validity, further trials should be included in future analyses. A direct comparison of angiography and iFR may also be advised. When talking about those further studies, not only longer follow-up periods are needed to proof better outcomes for iFR and FFR guided coronary interventions regarding MACE, but also different clinical outcomes have to analyzed.
University Hospital Mannheim is a member of DZHK (Deutsches Zentrum für Herz-Kreislauf-Forschung, German Centre for Cardiovascular Research, partner site Heidelberg/Mannheim). The authors would like to thank Mr. Volker Braun from the Library of the Medical Faculty of Mannheim of the University of Heidelberg for helping with the systematic literature review.
No funding was received.
The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.
SB, MB, IA and DL made substantial contributions to the design of the study, the acquisition and interpretation of data, drafting of the manuscript, revision of the manuscript for important intellectual content, and agree to be accountable for all aspects of the work in ensuring that questions associated with the accuracy or integrity of any part of the study are appropriately investigated and resolved. KSEM, SH, FE, ACS and TB made substantial contributions to the acquisition and analysis of data, and drafted the manuscript. All authors gave final approval of the version to be published.
Not applicable.
Not applicable.
The authors declare that they have no competing interests.
coronary artery disease
coronary artery bypass graft
drug eluting stents
fractional flow reserve
instantaneous wave-free ratio
major adverse cardiac event
myocardial infarction
odds ratio
percutaneous coronary intervention
randomized clinical trial
Table assessing risk of bias.
Flow chart representing the study selection process.
Forest plots showing the statistical results of 1-year clinical outcomes of FFR or angiography guided percutaneous coronary intervention. All four plots show a non-significant tendency towards FFR; Major Adverse Cardiac Events OR: 0.78 [95% CI: 0.59–1.04]. FFR, Fractional Flow Reserve.
Forest plots showing the statistical results of 1-year clinical outcomes of FFR or iFR guided percutaneous coronary intervention. There is no significant superiority of FFR over iFR; Major adverse cardiac events OR: 0.97 [95% CI: 0.76–1.23]. FFR, Fractional Flow Reserve; iFR, instantaneous wave-free ratio.
Characteristics of the included studies.
A, Studies comparing FFR guided PCI and angiography guided PCI | ||||||||
---|---|---|---|---|---|---|---|---|
Author, year | Design | Centers (Countries) | Number of enrolled patients for each method |
Indication for PCI | Exclusion criteria | Outcomes reported | Maximum Follow-up period (months) | (Refs.) |
Tonino |
Prospective RCT | 20 (N.A.) | 509 (FFR) 496 (Angio) | Multivessel CAD (50% of the vessel diameter in at least two major epicardial coronary arteries) | Recent STEMI (<5 days); NSTEMI with peak creatinine kinase >1,000 U/l; significant left main CAD; previous CABG; cardiogenic shock; extremely tortuous or calcified coronary arteries; life expectancy <2 years; contraindication for drug-eluding stents; pregnancy | Primary endpoint: MACE Secondary endpoints: Procedure time; amount of contrast agent; functional CCS class (after 1 year); HRQoL; number of antianginal medication; individual components of MACE; MACE at 30 days and 6 months; cost-effectiveness | 12 | ( |
Puymirat |
Retrospective, nonrandomized | 1 (1) | 222 (FFR) 495 (Angio) | Stable or unstable Angina in small coronary vessel (<3 mm diameter) | Patients with PCI treatment in vessels ≥3 mm; bypass graft stenting; STEMI or non-STEMI; PCI without stenting | Primary endpoint: MACE Secondary endpoints: Stent thrombosis; periprocedural MI; bleeding complications (major thrombolysis in MI); use of transfusion during hospital stay | 60 | ( |
Li |
Retrospective, nonrandomized | 1 (1) | 1,090 (FFR) 6,268 (Angio) | Patients referred for revascularization | STEMI; cardiogenic shock; referred for CABG | Primary endpoint: MACE Secondary endpoint: death; MI; repeated revascularization | 84 | ( |
Chen |
Prospective RCT | 8 (1) | 160 (FFR) 160 (Angio) | Silent ischemia, Stable or unstable Angina with a single true coronary bifurcation lesion (diameter of stenosis ≤50% in both the main vessel and the side branch, each with a reference diameter of ≥2.5 to ≤4.5 mm) | MI within one month; left ventricular ejection <30%; previous CABG; a distal left main coronary artery trifurcation lesion with a no canalized right coronary artery chronic total occlusion; calcification requiring rotational atherectomy; planned surgery necessitating antiplatelet therapy interrupting within 6 months post-PCI; study drug contraindication or intolerance; estimated glomerular filtration rate <40 ml/min/1.73 m2: platelet count <10×109/l; liver dysfunction; pregnancy; expected life span <1 year | Primary endpoint: 1 year rate of MACE Secondary endpoints: individual MACE (cardiac death, MI or TVR); stent thrombosis; restenosis | 12 | ( |
Layland |
Prospective RCT | 6 (1) | 176 (FFR) 174 (Angio) | NSTEMI and at least one risk factor for CAD with invasive management planned or history of recurrent ischemic symptoms within 5 days | Presence of ischemic symptoms without medical therapy; hemodynamic instability; MI with persistent ST elevation; anti-platelet intolerance; planned non-coronary surgery; history of CABG; coronary disease; life expectancy <1 year | Primary endpoint: Difference in patient numbers allocated to medical treatment between the PCI and the FFR guided group Secondary endpoint: Feasibility and safety of routine FFR; relationship between FFR and stenosis severity as assessed by angiography; MACE; hospital resources; HRQoL | 12 | ( |
Park |
Prospective RCT | 6 (1) | 114 (FFR) 115 (Angio) | Intermediate coronary stenosis in a native coronary artery with a reference diameter of <2.5 mm | Angiographically significant left main disease; cardiogenic shock; chronic kidney disease; a life expectancy <2 years; conductions disturbance more than first degree AV-block; contraindication to adenosine | Primary endpoint: MACE (after 2 and 5 years) | 60 | ( |
De Backer |
Retrospektive, nonrandomized | 1 (1) | 695 (FFR) 695 (Angio) | Stable Angina | Coronary stenosis <50% or >89% | Primary endpoint: MACE Secondary endpoints: Death; MI; repeated revascularization; combined endpoint of death and MI | 48 | ( |
Davies |
Prospective RCT | 49 (19) | 1,250 (FFR) 1,242 (iFR) | Intermediate coronary stenosis | Tandem stenosis, previous CABG, significant left main artery stenosis, total coronary occlusion, restenosis, hemodynamic instability, contraindication to adenosine administration or PCI or drug eluting stent, heavily calcified or tortuous vessels, significant hepatic or lung disease or malignant disease with unfavorable prognosis, pregnancy, severe valvular heart disease, recent STEMI, more than one target vessel | Primary endpoint: MACE | 12 | ( |
Götberg |
Prospective RCT | 15 (3) | 1,007 (FFR) 1,012 (iFR) | Stable or unstable Angina, NSTEMI | Previous CABG; life expectancy <1 year; unstable hemodynamics | Primary endpoint: MACE Secondary endpoints: MI; death; unplanned revascularization; chest discomfort during the procedure; TVR; stent thrombosis; restenosis | 12 | ( |
Total: 2,966 (FFR) and 8,387 (Angio)
Total: 2,257 (FFR) and 2,254 (iFR). Angio, angiography; CAD, coronary artery disease; CABG, coronary artery bypass graft; CCS, canadian cardiovascular society; FFR, fractional flow reserve; HRGoL, health-related quality of Life; iFR, instantaneous wave-free ratio; MACE, major adverse coronary event; MI, myocardial infarction, NSTEMI; non ST elevation myocardial infarction; OS, observational study; PCI, percutaneous coronary intervention; RCT, randomized controlled trial; STEMI, ST elevation myocardial infarction; TLR, target lesion revascularization; TVR, target vessel revascularization.
Patient characteristics of the included studies.
A, Studies comparing FFR guided PCI and angiography guided PCI | |||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Author, year | Method used for PCI | Patients | Age ± SD | BMI ± SD (kg/m2) | Male (%) | HTN (%) | Diabetes (%) | HC (%) | Current smoking (%) | Family history of CAD (%) | Prior MI (%) | MVD (%) | (Refs.) |
Tonino | FFR | 509 | 64.6±10.3 | N.A. | 384 (75.4) | 312 (61.3) | 123 (24.2) | 366 (71.9) | 138 (27.1) | 205 (40.3) | 187 (36.7) | 509 (100) | ( |
Angiography | 496 | 64.2±10.2 | N.A. | 360 (72.6) | 327 (65.9) | 125 (25.2) | 362 (73.0) | 156 (31.5) | 190 (38.3) | 180 (36.3) | 496 (100) | ||
Puymirat | FFR | 222 | 71.6±9.8 | 26.6±4.3 | 129 (58) | 130 (59) | 58 (26) | 137 (62) | 86 (39) | 77 (35) | N.A. | 38 (17) | ( |
Angiography | 495 | 71.7±10.6 | 27.0±4.4 | 336 (68) | 323 (65) | 163 (33) | 333 (67) | 226 (46) | 143 (29) | N.A. | 46 (9) | ||
Li | FFR | 1,090 | 65.7±11.3 | 30.4±5.8 | 683 (62.7) | 864 (79.2) | 306 (28.0) | 608 (55.7) | 140 (12.8) | N.A. | 270 (25) | 73 (19.8) | ( |
Angiography | 6,268 | 67.9±11.6 | 30.2±5.9 | 4,416 (70.4) | 4,897 (78.1) | 1,862 (29.7) | 5,119 (81.6) | 836 (13.3) | N.A. | 1,882 (31.0) | 2186 (19) | ||
Chen | FFR | 160 | 65.2±9.6 | N.A. | 121 (75.6) | 116 (72.5) | 48 (30.0) | 27 (16.9) | 66 (41.3) | N.A. | 12 (7.5) | 112 (69.8) | ( |
Angiography | 160 | 65.4±9.2 | N.A. | 116 (72.5) | 106 (68.3) | 43 (26.9) | 32 (20.0) | 64 (40.0) | N.A. | 19 (11.9) | 110 (68.8) | ||
Layland | FFR | 176 | 62.3±11.0 | N.A. | 133 (75.6) | 78 (44.3) | 26 (14.8) | 71 (40.3) | 72 (40.9) | N.A. | 22 (12.5) | 51 (29.0) | ( |
Angiography | 174 | 61.6±11.1 | N.A. | 127 (73.0) | 81 (46.6) | 26 (14.9) | 56 (32.2) | 71 (40.8) | N.A. | 24 (13.8) | 55 (31.6) | ||
Park | FFR | 114 | 62±10 | N.A. | 83 (72.8) | 73 (64) | 30 (26) | 80 (70) | 30 (26) | N.A. | 22 (19) | 72 (63) | ( |
Angiography | 115 | 63±10 | N.A. | 87 (75.7) | 65 (57) | 39 (34) | 78 (68) | 38 (33) | N.A. | 20 (17) | 66 (57) | ||
De Backer | FFR | 695 | 64.6±10.5 | 28.3±10.6 | 511 (73.5) | 465 (66.9) | 179 (25.8) | 511 (73.5) | 173 (24.9) | 343 (49.4) | 238 (34.2) | 199 (28.7) | ( |
Angiography | 695 | 64.7±10.3 | 27.7±7.9 | 507 (72.9) | 477 (68.6) | 164 (23.6) | 514 (74.0) | 180 (25.9) | 328 (47.2) | 237 (34.1) | 202 (29.1) | ||
Davies | FFR | 1,250 | 65.2±10.6 | N.A. | 929 (74.3) | 884 (70.7) | 376 (30.1) | 792 (63.4) | 262 (21.0) | N.A. | 376 (30.1) | 519 (41.5) | ( |
iFR | 1,242 | 65.5±10.8 | N.A. | 962 (77.5) | 873 (70.3) | 382 (30.8) | 794 (63.9) | 243 (19.6) | N.A. | 358 (28.8) | 505 (40.7) | ||
Götberg | FFR | 1,007 | 67.4±9.2 | 27.6 ±4.3 | 766 (75.2) | 710 (69.7) | 213 (20.9) | 704 (69.2) | 167 (16.3) | N.A. | 335 (32.9) | 368 (36.1) | ( |
iFR | 1,012 | 67.6±9.6 | 27.6 ±4.3 | 756 (74.2) | 730 (71.6) | 232 (22.8) | 733 (71.9) | 159 (15.6) | N.A. | 337 (33.1) | 364 (35.7) |
BMI, Body-mass index; CAD, coronary artery disease; FFR, fractional flow-reserve; HC, hypercholesterolemia; HTN, hypertension; iFR®, Instantaneous Wave-free Ratio; MI, myocardial infarction; MVD, multi-vessel-disease; N.A., not available; PCI, percutaneous coronary intervention; SD, standard deviation.
Primary endpoints at 12 months of the included studies.
A, Studies comparing FFR guided PCI and angiography guided PCI | |||||||
---|---|---|---|---|---|---|---|
Author, year | Method used for PCI | Patients | Death from any cause (%) | Myocardial infarction (%) | Unplanned revascularization (%) | MACE (%) | (Refs.) |
Tonino |
FFR | 509 | 9 (1.8) | 29 (5.7) | 33 (6.5) | 67 (13.2) | ( |
Angiography | 496 | 15 (3.0) | 43 (8.7) | 47 (9.5) | 91 (18.3) | ||
Puymirat |
FFR | 222 | 3 (1.4) | N.A. | 10 (4.5) | 13 (5.9) | ( |
Angiography | 479 | 13 (2.7) | N.A. | 59 (12.3) | 90 (18.8) | ||
Li |
FFR | 1,090 | 120 (11.0) | 135 (18.2) | N.A. | 206 (18.9) | ( |
Angiography | 6,268 | 690 (11.0) | 826 (13.2) | N.A. | 1,292 (20.6) | ||
Chen |
FFR | 160 | 3 (1.9) | 19 (11.9) | 9 (5.6) | 29 (18.1) | ( |
Angiography | 160 | 2 (1.3) | 22 (13.8) | 11 (6.9) | 29 (18.1) | ||
Layland |
FFR | 176 | 5 (2.8) | 11 (6.2) | N.A. | 14 (8.0) | ( |
Angiography | 174 | 3 (1.7) | 15 (8.6) | N.A. | |||
Park |
FFR | 114 | N.A. | N.A. | N.A. | 5 (4.4) | ( |
Angiography | 115 | N.A. | N.A. | N.A. | |||
De Backer |
FFR | 695 | 110 (15.8) | 217 (31.2) | 254 (36.5) | 255 (36.7) | ( |
Angiography | 695 | 191 (27.5) | 210 (30.2) | 231 (33.2) | 236 (34.0) | ||
Davies |
FFR | 1,182 | 13 (1.1) | 28 (2.4) | 63 (5.3) | 83 (7.0) | ( |
iFR | 1,148 | 22 (1.9) | 31 (2.7) | 46 (4.0) | 78 (6.8) | ||
Götberg |
FFR | 1,007 | 12 (1.2) | 17 (1.7) | 46 (4.6) | 61 (6.1) | ( |
iFR | 1,012 | 15 (1.5) | 22 (2.2) | 47 (4.6) | 68 (6.7) |
FFR, fractional flow-reserve; iFR®, instantaneous wave-free ratio; MACE, major adverse cardiac events; N.A., not available; PCI, percutaneous coronary intervention.