Quantitative flow ratio-guided strategy versus angiography-guided strategy for percutaneous coronary intervention: Rationale and design of the FAVOR III China trial

Quantitative flow ratio or angiography for the assessment of non-culprit lesions in acute coronary syndromes, a randomized trial

BACKGROUND

Patients undergoing percutaneous coronary intervention for acute coronary syndromes often have multivessel disease (MVD). Quantitative flow ratio (QFR) is an angiography-based technology that may help quantify the functional significance of non-culprit lesions, with the advantage that measurements are possible also once the patient is discharged from the catheterization laboratory.

AIM

Our two-center, randomized superiority trial aimed to test whether QFR, as compared to angiography, modifies the rate of non-culprit lesion interventions (primary functional endpoint) and improves the outcomes of patients with acute coronary syndromes and MVD (primary clinical endpoint).

METHODS

In total, 202 consecutive patients (64 [56-71] years of age, 160 men) with STEMI (n = 69 (34%)), NSTEMI (n = 94 (47%)), or unstable angina (n = 39 (19%)) and MVD who had undergone successful treatment of all culprit lesions were randomized 1:1 to angiography- vs. QFR-guided delayed revascularization of 246 non-culprit stenoses (1.2/patient).

RESULTS

The proportion of patients assigned to medical treatment versus percutaneous intervention was not different between groups (angiography group: 45 (45%) vs. QFR: 56 (55%), P = 0.125; relative risk = 0.80 (0.60-1.06)). At 12 months, a primary clinical endpoint event (composite of death, nonfatal myocardial infarction, revascularization, and significant angina) occurred in 24 patients (angiography-guided) and 23 patients (QFR-guided; P = 0.637, HR = 1.16 [0.63-2.15]). None of its components was different between groups.

DISCUSSION

QFR guidance based on analysis of images from the primary intervention was not associated with a difference in the rate of non-culprit lesion staged revascularization nor in the 12-month incidence of clinical events in patients with acute coronary syndromes and multivessel disease.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov Registry (NCT04808310).

Comparison among various physiology and angiography-guided strategies for deferring percutaneous coronary intervention: A network meta-analysis

BACKGROUND/PURPOSE

It is unclear whether coronary physiology or coronary angiography (CA)-guided strategy is the more preferable approach for deferring percutaneous coronary intervention (PCI). We sought to evaluate the clinical efficacy of various PCI strategies through a network meta-analysis of randomized controlled trials (RCTs).

METHODS/MATERIALS

We searched multiple databases for RCTs investigating the impact of the following strategies for the purpose of determining whether or not to defer PCI: fractional flow reserve, instantaneous wave-free ratio, quantitative flow ratio (QFR), and CA. We conducted a network meta-analysis for trial-defined major adverse cardiovascular events (MACE), all-cause death, cardiovascular death, myocardial infarction (MI), target lesion revascularization (TLR), and stent thrombosis. We performed a subgroup analysis for those with acute coronary syndrome (ACS).

RESULTS

Our search identified 12 eligible RCTs including a total of 13,177 patients. QFR-guided PCI was associated with reduced MACE, MI, and TLR compared with CA-guided PCI (relative risk (RR) 0.68; 95 % confidence interval (CI] [0.49 to 0.94], RR 0.58; 95 % CI [0.36 to 0.96], and RR 0.58; 95 % CI [0.38 to 0.91], respectively). There were no significant differences in any pairs for all-cause death, cardiovascular death, or stent thrombosis. QFR was ranked the best in most outcomes. In the subgroup analysis of the ACS cohort, there were no significant differences in MACE between any comparisons.

CONCLUSIONS

QFR was associated with reduced MACE, MI, and TLR compared with CA, and ranked the best in most outcomes. However, this was not applied in the ACS cohort.

Effect of hemoglobin A1c management levels on coronary physiology evaluated by quantitative flow ratio in patients who underwent percutaneous coronary intervention

AIMS/INTRODUCTION

The coronary physiology and prognosis of patients with different hemoglobin A1c (HbA1c) levels after percutaneous coronary intervention (PCI) are currently unknown. The aim of this study was to assess the effect of different levels of HbA1c control on coronary physiology in patients who underwent PCI for coronary heart disease combined with type 2 diabetes mellitus by quantitative flow ratio (QFR).

MATERIALS AND METHODS

Patients who successfully underwent PCI and completed 1-year coronary angiographic follow up were enrolled, clinical data were collected, and QFR at immediate and 1-year follow up after PCI was retrospectively analyzed. A total of 257 patients (361 vessels) were finally enrolled and divided into the hemoglobin A1c (HbA1c)-compliance group (103 patients, 138 vessels) and non-HbA1c-compliance group (154 patients, 223 vessels) according to the HbA1c cut-off value of 7%. We compared the results of QFR analysis and clinical outcomes between the two groups.

RESULTS

At 1-year follow up after PCI, the QFR was significantly higher (0.94 ± 0.07 vs 0.92 ± 0.10, P = 0.019) and declined less (0.014 ± 0.066 vs 0.033 ± 0.095, P = 0.029) in the HbA1c-compliance group. Meanwhile, the incidence of physiological restenosis was lower in the HbA1c-compliance group (2.9% vs 8.5%, P = 0.034). Additionally, the target vessel revascularization rate was lower in the HbA1c-compliance group (6.8% vs 16.9%, P = 0.018). Furthermore, HbA1c ≥7% (OR 2.113, 95% confidence interval 1.081-4.128, P = 0.029) and QFR decline (OR 2.215, 95% confidence interval 1.147-4.277, P = 0.018) were independent risk factors for target vessel revascularization.

CONCLUSION

Patients with well-controlled HbA1c levels have better coronary physiological benefits and the incidence of adverse clinical outcome events might be reduced.

Sex Differences in Clinical Outcomes Associated With Quantitative Flow Ratio-Guided Percutaneous Coronary Intervention

Background

FAVOR III China (Comparison of Quantitative Flow Ratio Guided and Angiography Guided Percutaneous Intervention in Patients with Coronary Artery Disease) reported improved clinical outcomes in quantitative flow ratio (QFR) relative to angiography-guided percutaneous coronary intervention (PCI), but the clinical impact of QFR-guided PCI according to sex remains unknown.

Objectives

The authors sought to compare sex differences in the 2-year clinical benefits of a QFR-guided PCI strategy and to evaluate the differences in outcomes between men and women undergoing contemporary PCI.

Methods

This study involved a prespecified subgroup analysis of the FAVOR III China trial, in which women and men were randomized to a QFR-guided strategy or a standard angiography-guided strategy. Sex differences in clinical benefit of the QFR guidance were analyzed for major adverse cardiac events (MACE), a composite of all-cause death, myocardial infarction, or ischemia-driven revascularization within 2 years.

Results

A total of 1,126 women and 2,699 men were eligible and the occurrence of 2-year MACE was similar between women and men (10.3% vs 10.5%; P = 0.96). Compared with an angiography-guided strategy, a QFR-guided strategy resulted in a 7.9% and 9.7% reduction in PCI rates in men and women, respectively. A QFR-guided strategy resulted in similar relative risk reductions for 2-year MACE in women (8.0% vs 12.7%; HR: 0.62; 95% CI: 0.42-0.90) and men (8.7% vs 12.4%; HR: 0.69; 95% CI: 0.54-0.87) (Pinteraction = 0.61). Furthermore, QFR values were not significantly different between men and women with various angiographic stenosis categories.

Conclusions

A QFR-guided PCI strategy resulted in improved MACE in both men and women at 2 years compared with an angiography-guided PCI strategy. The FAVOR III China Study [FAVOR III China]; (NCT03656848).

Coronary Artery Stenosis Evaluation by Angiography-Derived FFR: Validation by Positron Emission Tomography and Invasive Thermodilution

BACKGROUND

Fractional flow reserve (FFR) derived from invasive coronary angiography (QFR) is promising for evaluation of intermediate coronary artery stenosis.

OBJECTIVES

The authors aimed to compare the diagnostic performance of QFR and the guideline-recommended invasive FFR using 82Rubidium positron emission tomography (82Rb-PET) myocardial perfusion imaging as reference standard.

METHODS

This is a prospective, observational study of symptomatic patients with suspected obstructive coronary artery disease on coronary computed tomography angiography (≥50% diameter stenosis in ≥1 vessel). All patients were referred to 82Rb-PET and invasive coronary angiography with FFR and QFR assessment of all intermediate (30%-90% diameter stenosis) stenoses. Main analyses included a comparison of the ability of QFR and FFR to identify reduced myocardial blood flow (<2 mL/g/min) during vasodilation and/or relative perfusion abnormalities (summed stress score ≥4 in ≥2 adjacent segments).

RESULTS

A total of 250 patients (320 vessels) with indication for invasive physiological assessment were included. The continuous relationship of 82Rb-PET stress myocardial blood flow per 0.10 increase in FFR was +0.14 mL/g/min (95% CI: 0.07-0.21 mL/g/min) and +0.08 mL/g/min (95% CI: 0.02-0.14 mL/g/min) per 0.10 QFR increase. Using 82Rb-PET as reference, QFR and FFR had similar diagnostic performance on both a per-patient level (accuracy: 73%; 95% CI: 67%-79%; vs accuracy: 71%; 95% CI: 64%-78%) and per-vessel level (accuracy: 70%; 95% CI: 64%-75%; vs accuracy: 68%; 95% CI: 62%-73%). The per-vessel feasibility was 84% (95% CI: 80%-88%) for QFR and 88% (95% CI: 85%-92%) for FFR by intention-to-diagnose analysis.

CONCLUSIONS

With 82Rb-PET as reference modality, the wire-free QFR solution showed similar diagnostic accuracy as invasive FFR in evaluation of intermediate coronary stenosis. (DAN-NICAD - Danish Study of Non-Invasive Diagnostic Testing in Coronary Artery Disease; NCT02264717).

Long-term prognostic value of Murray law-based quantitative flow ratio in jailed left circumflex coronary artery after left main crossover stenting

We aimed to evaluate the impact of new Murray law-based QFR of jailed left circumflex coronary artery (LCx) on long-term clinical outcomes after left main coronary artery (LM) simple crossover stenting. 164 patients who underwent LM-to-left anterior descending coronary artery simple crossover stenting and had appropriate angiographic view of LCx for QFR computation were enrolled. The primary clinical outcome was the 5-year target lesion failure (TLF), defined as a composite of cardiac death, a target vessel myocardial infarction or target lesion repeat revascularization. The mean QFR of the LCx after LM stent implantation was 0.88 ± 0.09, and 29 patients (17.7%) had a low QFR (< 0.80), which was significantly associated with a higher 5-year rate of TLF when compared with the high QFR group (27.6% vs. 6.7%; HR: 4.235; 95% CI 1.21-14.95; p = 0.0015). The 5-year LCx ostium-related TLR rate in the low QFR group was also higher (17.2% vs. 3.0% in the high QFR group; HR: 6.07, 95% CI 1.63-22.59, p = 0.002). In a multivariate Cox regression analysis, a low QFR in the LCx after LM stenting was an independent predictor of the 5-year TLF rate (HR: 3.21, 95% CI 1.21-8.53; p = 0.019). ROC analysis showed that QFR a negative predictive value (NPV) of 89.6% ([AUC] 0.73, 95% CI 0.58-0.88, p < 0.05), the cutoff point is 0.85. The patients with a low QFR (< 0.80) in jailed LCX after LM simple crossover stenting had worse 5-year outcomes than those with a high QFR. Conversely, a QFR ≥ 0.85 of jailed LCx could serve as a good predictor of low risk of adverse outcome in LCx ostium. The QFR computation of the jailed LCx may be helpful to determine whether an additional procedure is required for the jailed side branch.

Data simulation to forecast the outcomes of the FAVOR III China trial

BACKGROUND

FAVOR III China (F3C) is a large-scale randomized trial comparing QFR-guided and angiography-guided percutaneous coronary intervention (PCI) strategies. The aim of current study was to assess the feasibility of predicting the 1-year outcomes of the F3C trial using simulation of retrospectively assessed quantitative flow ratio (QFR) data obtained from the all-comers PANDA III trial.

METHODS

Among 2348 subjects from the PANDA III trial, angiography from 1391 patients was able to be analyzed with QFR. Each subject from the F3C was matched to a PANDA III patient according to the five baseline characteristics (age, sex, diabetes, multivessel disease, and existence of any vessel with diameter stenosis % >90% and thrombolysis in myocardial infarction flow <3) through a bootstrapping sampling process. Outcome predictions were based on these blinded baseline data. The primary endpoint was a composite of death, myocardial infarction, or revascularization at 1 year.

RESULTS

Among the patients with analyzable QFR, 814 patients were able to be matched to F3C patients undergoing a QFR-guided treatment strategy. After 10,000 simulations, the patients in the QFR-guided group were simulated to have a 1.9% (95% predictive intervals: -3.5% to -0.3%) absolute reduction of the occurrence of the primary study endpoint compared with the angiography-guided group. In total, 72.7% (7266/10,000) simulated point estimates fell within the actual 95% CI of F3C (-4.7% to -1.4%).

CONCLUSIONS

Using a simulation process based on a comparison to an existing trial cohort, the primary results of a prospectively conducted randomized controlled trial could be predicted with reasonable precision.

Short-Term Risk Stratification of Non-Flow-Limiting Coronary Stenosis by Angiographically Derived Radial Wall Strain

BACKGROUND

Deferred revascularization of mildly stenotic coronary vessels based exclusively on physiological evaluation is associated with up to 5% residual incidence of future adverse events at 1 year.

OBJECTIVES

We aimed to evaluate the incremental value of angiography-derived radial wall strain (RWS) in risk stratification of non-flow-limiting mild coronary narrowings.

METHODS

This is a post hoc analysis of 824 non-flow-limiting vessels in 751 patients from the FAVOR III China (Comparison of Quantitative Flow Ratio Guided and Angiography Guided Percutaneous Intervention in Patients With Coronary Artery Disease) trial. Each individual vessel had ≥1 mildly stenotic lesion. The primary outcome was vessel-oriented composite endpoint (VOCE), defined as the composite of vessel-related cardiac death, vessel-related myocardial infarction (nonprocedural), and ischemia-driven target vessel revascularization at 1-year follow-up.

RESULTS

During 1-year follow-up, VOCE occurred in 46 of 824 vessels, with a cumulative incidence of 5.6%. Maximum RWS (RWSmax) was predictive of 1-year VOCE with an area under the curve of 0.68 (95% CI: 0.58-0.77; P < 0.001). The incidence of VOCE was 14.3% in vessels with RWSmax >12% vs 2.9% in those with RWSmax ≤12%. In the multivariable Cox regression model, RWSmax >12% was a strong independent predictor of 1-year VOCE in deferred non-flow-limiting vessels (adjusted HR: 4.44; 95% CI: 2.43-8.14; P < 0.001). The risk of deferred revascularization based on combined normal RWSmax and Murray-law-based quantitative flow ratio (μQFR) was significantly reduced compared with μQFR alone (adjusted HR: 0.52; 95% CI: 0.30-0.90; P = 0.019).

CONCLUSIONS

Among vessels with preserved coronary flow, angiography-derived RWS analysis has the potential to further discriminate vessels at risk of 1-year VOCE. (Comparison of Quantitative Flow Ratio Guided and Angiography Guided Percutaneous Intervention in Patients With Coronary Artery Disease [FAVOR III China Study]; NCT03656848).

Outcomes of Functionally Complete vs Incomplete Revascularization: Insights From the FAVOR III China Trial

BACKGROUND

Functional complete revascularization (FCR) after percutaneous coronary intervention (PCI) as determined by the residual functional SYNTAX score (rFSS) based on pressure wire fractional flow reserve assessment has been associated with an improved prognosis.

OBJECTIVES

This study sought to determine the rates and clinical implications of FCR as assessed by the quantitative flow ratio (QFR), and to determine the outcomes of pre-PCI QFR guidance compared with standard angiography guidance in patients achieving and not achieving FCR after PCI.

METHODS

In the randomized, sham-controlled, blinded, multicenter FAVOR (Comparison of Quantitative Flow Ratio Guided and Angiography Guided Percutaneous Intervention in Patients with Coronary Artery Disease) III China trial, QFR-guided PCI reduced the 1-year rate of major adverse cardiac events (MACE) compared with angiography-guided PCI. In the present prespecified substudy, the incidence of MACE was compared according to the presence of post-PCI FCR (rFSS = 0 based on core laboratory-assessed QFR) in the QFR-guided and angiography-guided groups.

RESULTS

Among 3,781 patients with available rFSS assessments, 3,221 (85.2%) achieved FCR, including 88.1% after QFR guidance and 82.2% after angiography guidance (P < 0.001). Patients with FCR had a markedly lower rate of 1-year MACE compared with those with functional incomplete revascularization (FIR) (rFSS ≥1) (5.1% vs 19.7%; P < 0.001). Prognostic models including the rFSS had higher discrimination and reclassification ability than those with the anatomic residual SYNTAX score. The relative risks for 1-year MACE with QFR-guided compared with the angiography-guided lesion selection were consistent in patients achieving FCR (4.1% vs 6.3%; HR: 0.65; 95% CI: 0.47-0.88) and in those with FIR (18.7% vs 20.4%; HR: 0.90; 95% CI: 0.61-1.32) (P_interaction = 0.19).

CONCLUSIONS

In this large-scale trial, achieving FCR after PCI was associated with markedly lower 1-year rates of MACE. Compared with standard angiography guidance, QFR-guided PCI lesion selection improved the likelihood of achieving FCR and improved 1-year clinical outcomes in patients with both FCR and FIR.

Characterization of quantitative flow ratio and fractional flow reserve discordance using doppler flow and clinical follow-up

The physiological mechanisms of quantitative flow ratio and fractional flow reserve disagreement are not fully understood. We aimed to characterize the coronary flow and resistance profile of intermediate stenosed epicardial coronary arteries with concordant and discordant FFR and QFR. Post-hoc analysis of the DEFINE-FLOW study. Anatomical and Doppler-derived physiological parameters were compared for lesions with FFR+QFR- (n = 18) vs. FFR+QFR+ (n = 43) and for FFR-QFR+ (n = 34) vs. FFR-QFR- (n = 139). The association of QFR results with the two-year rate of target vessel failure was assessed in the proportion of vessels (n = 195) that did not undergo revascularization. Coronary flow reserve was higher [2.3 (IQR: 2.1-2.7) vs. 1.9 (IQR: 1.5-2.4)], hyperemic microvascular resistance lower [1.72 (IQR: 1.48-2.31) vs. 2.26 (IQR: 1.79-2.87)] and anatomical lesion severity less severe [% diameter stenosis 45.5 (IQR: 41.5-52.5) vs. 58.5 (IQR: 53.1-64.0)] for FFR+QFR- lesions compared with FFR+QFR+ lesions. In comparison of FFR-QFR+ vs. FFR-QFR- lesions, lesion severity was more severe [% diameter stenosis 55.2 (IQR: 51.7-61.3) vs. 43.4 (IQR: 35.0-50.6)] while coronary flow reserve [2.2 (IQR: 1.9-2.9) vs. 2.2 (IQR: 1.9-2.6)] and hyperemic microvascular resistance [2.34 (IQR: 1.85-2.81) vs. 2.57 (IQR: 2.01-3.22)] did not differ. The agreement and diagnostic performance of FFR using hyperemic stenosis resistance (> 0.80) as reference standard was higher compared with QFR and coronary flow reserve. Disagreement between FFR and QFR is partly explained by physiological and anatomical factors. Clinical Trials Registration https://www.clinicaltrials.gov ; Unique identifier: NCT01813435.

Research Progress of Machine Learning and Deep Learning in Intelligent Diagnosis of the Coronary Atherosclerotic Heart Disease

The coronary atherosclerotic heart disease is a common cardiovascular disease with high morbidity, disability, and societal burden. Early, precise, and comprehensive diagnosis of the coronary atherosclerotic heart disease is of great significance. The rise of artificial intelligence technologies, represented by machine learning and deep learning, provides new methods to address the above issues. In recent years, artificial intelligence has achieved an extraordinary progress in multiple aspects of coronary atherosclerotic heart disease diagnosis, including the construction of intelligent diagnostic models based on artificial intelligence algorithms, applications of artificial intelligence algorithms in coronary angiography, coronary CT angiography, intravascular imaging, cardiac magnetic resonance, and functional parameters. This paper presents a comprehensive review of the technical background and current state of research on the application of artificial intelligence in the diagnosis of the coronary atherosclerotic heart disease and analyzes recent challenges and perspectives in this field.

Outcomes of quantitative flow ratio-based percutaneous coronary intervention in an all-comers study

BACKGROUND

Quantitative flow ratio (QFR) is a novel angiography-based physiological index for fast computation of fractional flow reserve without the use of a pressure wire or induction of hyperaemia.

AIMS

We sought to investigate the prevalence and prognostic implications of achieving physiology-consistent percutaneous coronary intervention (PCI) according to the baseline angiographic QFR in an all-comers cohort.

METHODS

QFR was retrospectively analysed from the angiograms of 1,391 patients enrolled in the randomised PANDA III trial. Patients in whom all functionally ischaemic vessels (baseline QFR ≤0.80) were treated and in whom all non-ischaemic vessels (baseline QFR >0.80) were deferred were termed as having had QFR-consistent treatment; otherwise, they were termed as having had QFR-inconsistent treatment. The major outcome was two-year major adverse cardiac events (MACE; a composite of all-cause death, all myocardial infarction (MI), or any ischaemia-driven revascularisation).

RESULTS

Overall, 814 (58.5%) patients had QFR-consistent PCI, while 577 (41.5%) patients received QFR-inconsistent PCI. Patients with QFR-consistent versus those with QFR-inconsistent treatment had a lower risk of two-year MACE (8.4% vs 14.7%; hazard ratio [HR] 0.56, 95% confidence interval [CI]: 0.41-0.78). After adjusting for differences in baseline covariates, two-year rates of MACE remained significantly lower in the QFR-consistent group (8.8% vs 13.6%; adjusted HR 0.64, 95% CI: 0.44-0.93), due mainly to reduced ischaemia-driven revascularisation (2.9% vs 8.0%; adjusted HR 0.35, 95% CI: 0.20-0.60).

CONCLUSIONS

In this post hoc analysis of an all-comers PCI trial, approximately 60% of patients were treated in accordance with what the QFR measurement would have recommended, the achievement of which was associated with improved two-year clinical outcomes. ClinicalTrials.gov identifier: NCT02017275.

Post-PCI outcomes predicted by pre-intervention simulation of residual quantitative flow ratio using augmented reality

BACKGROUND

The simulated residual quantitative flow ratio (QFR) computed from pre-intervention three-dimensional (3-D) coronary angiograms, which could theoretically predict actual post-percutaneous coronary intervention (PCI) QFR value, can be used for enhanced PCI via augmented reality. The study sought to investigate the concordance between simulated residual QFR and actual post-PCI QFR, and the prognostic value of simulated residual QFR.

METHODS

QFR assessment was retrospectively performed in treated vessels from the all-comers PANDA III trial. Three-step analysis was performed: 1) concordance between simulated residual QFR and post-PCI QFR; 2) prognostic value of simulated residual QFR; and 3) forecast of outcomes by virtual randomized controlled trials (RCTs) between residual QFR and angiographic guidance.

RESULTS

Of 2989 treated vessels, 2146 (71.8%) with paired analyzable simulated residual QFR and post-PCI QFR were included. The simulated residual QFR and post-PCI QFR were strongly correlated (r = 0.976). Low simulated residual QFR (≤0.92) was independently associated with higher risk of 2-year vessel-oriented composite endpoint (adjusted hazard ratio: 5.50; 95% confidence interval: 3.03 to 10.0). Based upon 5000 iterations of virtual RCTs, simulated residual QFR-guided strategy was anticipated to have a 2.6% absolute reduction of 2-year incidence of target vessel failure compared with the angiography-guided strategy.

CONCLUSIONS

With high consistency to actual post-PCI QFR, the simulated residual QFR computed from pre-PCI 3-D coronary angiograms and augmented reality could predict functional outcome of the procedure and 2-year prognosis. Using data from PANDA III trial, the present study forecasted superiority of residual QFR-guided PCI strategy over angiographic guidance. Clinical Trial Registration Information URL: https://www.clinicaltrials.gov; Unique identifier: NCT02017275.

Angiographic quantitative flow ratio-guided coronary intervention (FAVOR III China): a multicentre, randomised, sham-controlled trial

BACKGROUND

Compared with visual angiographic assessment, pressure wire-based physiological measurement more accurately identifies flow-limiting lesions in patients with coronary artery disease. Nonetheless, angiography remains the most widely used method to guide percutaneous coronary intervention (PCI). In FAVOR III China, we aimed to establish whether clinical outcomes might be improved by lesion selection for PCI using the quantitative flow ratio (QFR), a novel angiography-based approach to estimate the fractional flow reserve.

METHODS

FAVOR III China is a multicentre, blinded, randomised, sham-controlled trial done at 26 hospitals in China. Patients aged 18 years or older, with stable or unstable angina pectoris or patients who had a myocardial infarction at least 72 h before screening, who had at least one lesion with a diameter stenosis of 50-90% in a coronary artery with a reference vessel of at least 2·5 mm diameter by visual assessment were eligible. Patients were randomly assigned to a QFR-guided strategy (PCI performed only if QFR ≤0·80) or an angiography-guided strategy (PCI based on standard visual angiographic assessment). Participants and clinical assessors were masked to treatment allocation. The primary endpoint was the 1-year rate of major adverse cardiac events, a composite of death from any cause, myocardial infarction, or ischaemia-driven revascularisation. The primary analysis was done in the intention-to-treat population. The trial was registered with ClinicalTrials.gov (NCT03656848).

FINDINGS

Between Dec 25, 2018, and Jan 19, 2020, 3847 patients were enrolled. After exclusion of 22 patients who elected not to undergo PCI or who were withdrawn by their physicians, 3825 participants were included in the intention-to-treat population (1913 in the QFR-guided group and 1912 in the angiography-guided group). The mean age was 62·7 years (SD 10·1), 2699 (70·6%) were men and 1126 (29·4%) were women, 1295 (33·9%) had diabetes, and 2428 (63·5%) presented with an acute coronary syndrome. The 1-year primary endpoint occurred in 110 (Kaplan-Meier estimated rate 5·8%) participants in the QFR-guided group and in 167 (8·8%) participants in the angiography-guided group (difference, -3·0% [95% CI -4·7 to -1·4]; hazard ratio 0·65 [95% CI 0·51 to 0·83]; p=0·0004), driven by fewer myocardial infarctions and ischaemia-driven revascularisations in the QFR-guided group than in the angiography-guided group.

INTERPRETATION

In FAVOR III China, among patients undergoing PCI, a QFR-guided strategy of lesion selection improved 1-year clinical outcomes compared with standard angiography guidance.

FUNDING

Beijing Municipal Science and Technology Commission, Chinese Academy of Medical Sciences, and the National Clinical Research Centre for Cardiovascular Diseases, Fuwai Hospital.

Relationship Between Immunoinflammation and Coronary Physiology Evaluated by Quantitative Flow Ratio in Patients With Coronary Artery Disease

Background: The association between coronary physiology and immunoinflammation has not been investigated. We performed a retrospective study using quantitative flow ratio (QFR) to evaluate the interaction between immunoinflammatory biomarkers and coronary physiology.

Methods: A total of 172 patients with CAD who underwent coronary arteriography (CAG) and QFR were continuously enrolled from May 2020 to February 2021. As a quantitative indicator of coronary physiology, QFR can reflect the functional severity of coronary artery stenosis. The target vessel measured by QFR was defined as that with the most severe lesions. Significant coronary anatomical stenosis was defined as 70% stenosis in the target vessel.

Results: Compared with the QFR > 0.8 group, interleukin (IL)-6, IL-10, tumor necrosis factor (TNF)-α, and interferon (IFN)-γ were increased and CD3⁺ and CD4⁺ T lymphocyte counts were decreased in the QFR ≤ 0.8 group. In addition, patients with DS ≤ 70% had higher IL-6, IL-10, and TNF-α levels and decreased CD3⁺ and CD4⁺ T lymphocyte counts than those with DS > 70%. Logistic regression analysis indicated IL-6 to be an independent predictor of significant coronary functional and anatomic stenosis (odds ratio, 1.125; 95% CI, 1.059–1.196; P < 0.001). Receiver operating characteristic (ROC) analyses showed that IL-6 > 6.36 was predictive of QFR ≤ 0.8 of the target vessel. The combination of IL-6, IL-10 and CD4 improved the value for predicting QFR ≤ 0.8 of the target vessel (AUC, 0.737; 95% CI, 0.661–0.810).

Conclusion: Among immunoinflammatory biomarkers, IL-6 was independently associated with a higher risk of QFR ≤ 0.8 of the target vessel. The combination of immunoinflammatory biomarkers was highly predictive of significant coronary functional and anatomic stenosis.

Integrated coronary disease burden and patterns to discriminate vessels benefiting from percutaneous coronary intervention

OBJECTIVE

To evaluate the prognostic implications of atherosclerosis functional pattern on ischemia-causing vessels received percutaneous coronary intervention (PCI) or conservative treatment.

BACKGROUND

Quantitative flow ratio (QFR)-derived pullback pressure gradient (PPG) index is recently proposed to characterize atherosclerosis functional pattern, but its prognostic value remains unclear.

METHODS

QFR-derived PPG index was retrospectively calculated in patients from the PANDA III trial. Vessels with low or high PPG treated by PCI or not were compared for the risk of 2-year vessel-oriented composite outcome (VOCO), which was a composite of vessel-related ischemia-driven revascularization, vessel-related myocardial infarction, or cardiac death.

RESULTS

A total of 1444 vessels were included while 94 (6.5%) VOCOs occurred within 2 years. Among physiologically ischemic vessels (QFR ≤ 0.80) treated by PCI, those with low PPG acquired higher VOCO risk than those with high PPG (8.4% vs. 3.8%; adjusted hazard ratio [HR] 2.13, 95% confidence interval [CI] 1.18 to 3.86), and a similar VOCO risk (8.4% vs. 7.8%; adjusted HR 1.11, 95%CI 0.70-1.78) compared to those treated by conservatively. After multiple adjustment, PPG index was an independent predictor for VOCO (HR 1.30, 95% CI 1.05-1.62). The addition of PPG to the model of clinical risk factors substantially improved the predictions of VOCO (C-index 0.67 vs. 0.62, net reclassification index 0.42).

CONCLUSIONS

PCI treatment was associated with improved outcomes in vessels with high PPG, but not for those with low PPG, which acquired similar risk of VOCO compared to vessels treated conservatively. QFR-derived PPG might assist the treatment strategy selection in ischemia-causing vessels.

Vessel fractional flow reserve in assessment of non-culprit lesions in ST elevation myocardial infarction

Objectives

We sought to evaluate the physiology of non-culprit lesions by using vessel fractional flow reserve (vFFR) among patients with ST elevation myocardial infarction (STEMI) and multivessel disease (MVD).

Methods

From January 2017 to December 2019, 354 patients with STEMI in the Taipei Veterans General Hospital Acute Myocardial Infarction Registry were screened. Patients who underwent successful primary percutaneous coronary intervention (PCI) for culprit lesions, with at least one non-culprit lesion with stenosis of ≥50%, were eligible. vFFR was computed retrospectively.

Results

A total of 156 patients with 217 non-culprit lesions were eligible for this study. Aortic root pressure and two good angiograms were available for 139 non-culprit lesions for vFFR analysis. Based on the vFFR analysis, 59 non-culprit lesions (43.2%) had a vFFR value >0.80, and PCI was deferred in 45 lesions (76.3%). Meanwhile, 80 non-culprit lesions (56.8%) had a vFFR value ≤0.80; however, PCI was only performed in 31 lesions (38.7%) (p=0.142). The incidence of vessel-oriented composite endpoint was numerically higher in non-culprit lesions with vFFR ≤0.80 than those with vFFR >0.80 (6.3% vs 1.7%, HR: 3.59, 95% CI: 0.42 to 30.8, p=0.243).

Conclusion

Functional incomplete revascularisation is common among patients with STEMI and MVD. The adoption of vFFR to assess non-culprit lesions may reclassify the coronary revascularisation strategy that is usually guided by angiography only in this acute setting.

Effect of Low-Density Lipoprotein Cholesterol Goal Achievement on Vascular Physiology Evaluated by Quantitative Flow Ratio in Patients Who Underwent Percutaneous Coronary Intervention

Purpose: The change in coronary physiology from lipid-lowering therapy (LLT) lacks an appropriate method of examination. Quantitative flow ratio (QFR) is a novel angiography-based approach allowing rapid assessment of coronary physiology. This study sought to determine the impact of low-density lipoprotein cholesterol (LDL-C) goal achievement on coronary physiology through QFR. Methods: Cases involving percutaneous coronary intervention (PCI) and 1-year angiographic follow-up were screened and assessed by QFR analysis. Patients were divided into two groups according to the LDL-C level at the 1-year follow-up: (1) goal-achievement group (LDL-C < 1.8 mmol/L or reduction of ≥50%, n = 146, lesion = 165) and (2) non-achievement group (n = 286, lesion = 331). All QFR data and major adverse cardiovascular and cerebrovascular events (MACCEs) at 1 year were compared between groups. Results: No differences between the groups in quantitative coronary angiography (QCA) data or QFR post-PCI were found. At the 1-year follow-up, lower percentage diameter stenosis (DS%) and percentage area stenosis (AS%) were recorded in the goal-achievement group (27.89 ± 10.16 vs. 30.93 ± 12.03, p = 0.010, 36.57 ± 16.12 vs. 41.68 ± 17.39, p = 0.003, respectively). Additionally, a better change in QFR was found in the goal-achievement group (0.003 ± 0.068 vs. -0.018 ± 0.086, p = 0.007), with a lower incidence of physiological restenosis and MACCEs (2.1 vs. 8.4%, p = 0.018, 5.4 vs. 12.6%, p = 0.021, respectively). Conclusion: Evaluated by QFR, patients who achieved the LDL-C goal appear to have a better coronary physiological benefit. This group of patients also has a better clinical outcome.

Cut-off values of lesion and vessel quantitative flow ratio in de novo coronary lesion post-drug-coated balloon therapy predicting vessel restenosis at mid-term follow-up

BACKGROUND

Drug-coated balloons (DCBs) have emerged as potential alternatives to drug-eluting stents in specific lesion subsets for de novo coronary lesions. Quantitative flow ratio (QFR) is a method based on the three-dimensional quantitative coronary angiography and contrast flow velocity during coronary angiography (CAG), obviating the need for an invasive fractional flow reserve procedural. This study aimed to assess the serial angiographic changes of de novo lesions post-DCB therapy and further explore the cut-off values of lesion and vessel QFR, which predict vessel restenosis (diameter stenosis [DS] ≥50%) at mid-term follow-up.

METHODS

The data of patients who underwent DCB therapy between January 2014 and December 2019 from the multicenter hospital were retrospectively collected for QFR analysis. From their QFR performances, which were analyzed by CAG images at follow-up, we divided them into two groups: group A, showing target vessel DS ≥50%, and group B, showing target vessel DS <50%. The median follow-up time was 287 days in group A and 227 days in group B. We compared the clinical characteristics, parameters during DCB therapy, and QFR performances, which were analyzed by CAG images between the two groups, in need to explore the cut-off value of lesion/vessel QFR which can predict vessel restenosis. Student's t test was used for the comparison of normally distributed continuous data, Mann-Whitney U test for the comparison of non-normally distributed continuous data, and receiver operating characteristic (ROC) curves for the evaluation of QFR performance which can predict vessel restenosis (DS ≥50%) at mid-term follow-up using the area under the curve (AUC).

RESULTS

A total of 112 patients with 112 target vessels were enrolled in this study. Group A had 41 patients, while group B had 71. Vessel QFR and lesion QFR were lower in group A than in group B post-DCB therapy, and the cut-off values of lesion QFR and vessel QFR in the ROC analysis to predict target vessel DS ≥50% post-DCB therapy were 0.905 (AUC, 0.741 [95% confidence interval, CI: 0.645, 0.837]; sensitivity, 0.817; specificity, 0.561; P < 0.001) and 0.890 (AUC, 0.796 [95% CI: 0.709, 0.882]; sensitivity, 0.746; specificity, 0.780; P < 0.001).

CONCLUSIONS

The cut-off values of lesion QFR and vessel QFR can assist in predicting the angiographic changes post-DCB therapy. When lesion/vessel QFR values are <0.905/0.890 post-DCB therapy, a higher risk of vessel restenosis is potentially predicted at follow-up.

Physiologic Assessment of Coronary Stenosis: Current Status and Future Directions

PURPOSE OF REVIEW

Percutaneous coronary intervention (PCI) is a commonly used treatment option in coronary artery disease (CAD). Reduced major adverse cardiovascular events (MACE) in those randomized to PCI compared to optimal medical therapy have been demonstrated only if it is performed for physiologically significant coronary lesions. Despite data demonstrating improved outcomes primarily in stable CAD and then acute settings, physiology-guided PCI remains underutilized. This review summarizes the evidence and commonly used methods for physiologic assessment of coronary stenosis.

RECENT FINDINGS

Fractional flow reserve (FFR) is the gold standard for the analysis of lesion severity. Its use is limited by the need for adenosine, which adds time, complexity, and potential adverse effects. Non-hyperemic instantaneous wave-free ratio-guided revascularization and quantitative flow reserve ratio assessment both have shown safety and effectiveness with improved patient outcomes. Coronary physiological assessment solves the ambiguity of coronary angiography. Detecting physiologically significant stenoses is crucial to decide which lesion needs to be treated. Technological advances have led to the development of new assessment indices in addition to FFR.

The new role of diagnostic angiography in coronary physiological assessment

The role of 'stand-alone' coronary angiography (CAG) in the management of patients with chronic coronary syndromes is the subject of debate, with arguments for its replacement with CT angiography on the one hand and its confinement to the interventional cardiac catheter laboratory on the other. Nevertheless, it remains the standard of care in most centres. Recently, computational methods have been developed in which the laws of fluid dynamics can be applied to angiographic images to yield 'virtual' (computed) measures of blood flow, such as fractional flow reserve. Together with the CAG itself, this technology can provide an 'all-in-one' anatomical and functional investigation, which is particularly useful in the case of borderline lesions. It can add to the diagnostic value of CAG by providing increased precision and reduce the need for further non-invasive and functional tests of ischaemia, at minimal cost. In this paper, we place this technology in context, with emphasis on its potential to become established in the diagnostic workup of patients with suspected coronary artery disease, particularly in the non-interventional setting. We discuss the derivation and reliability of angiographically derived fractional flow reserve (CAG-FFR) as well as its limitations and how CAG-FFR could be integrated within existing national guidance. The assessment of coronary physiology may no longer be the preserve of the interventional cardiologist.

Quantitative flow ratio as a new tool for angiography-based physiological evaluation of coronary artery disease: a review

The functional evaluation of coronary stenoses has obtained important clinical results in recent years, resulting in strong guideline recommendations. Nonetheless, the use of coronary wire-based functional evaluation has not yet become part of the routine in catheterization laboratories for several reasons, including the need to advance a wire into the coronary vessel to interrogate the stenosis. Angiography-derived indexes have been introduced to expand the current use of physiology to estimate the functional meaning of a stenosis on the basis of angiographic data only. The most studied and validated angiography-derived index is certainly the quantitative flow ratio. This article will summarize the basics of the quantitative flow ratio, the related validation studies and its current and future applications.

Borderline coronary lesion assessment with quantitative flow ratio and its relation to the instantaneous wave-free ratio

PURPOSE

Quantitative flow ratio (QFR) is a recently developed image-based index for the assessment of borderline coronary artery disease. We sought to investigate a correlation between QFR and instantaneous wave-free ratio (iFR) for the assessment of intermediate coronary stenoses.

MATERIALS AND METHODS

Patients with borderline coronary lesions (40-90% by visual assessment) undergoing iFR assessment were enrolled. QFR was derived from a modeled hyperemic flow velocity derived from angiography without adenosine-induced hyperemia. Pressure wire-derived iFR served as the reference.

RESULTS

Values of QFR and iFR from 110 vessels with a mean percent diameter stenosis of 44.6 ​± ​12.0% were compared. Mean iFR was 0.90 ​± ​0.07 and 38 (34.5%) had iFR ≤0.89. Mean QFR was 0.81 ​± ​0.10 and 44 (40%) had QFR ≤0.80. A good agreement between QFR and iFR measurements was confirmed with a mean difference of 0.09 (95%CI -0.027 to 0.207) and intraclass correlation coefficient of 0.87 (95%CI 0.81-0.91). The overall diagnostic accuracy (AUC in ROC analysis) of QFR in detecting iFR ≤0.89 was 0.87 (95%CI 0.79-0.93; p ​< ​0.001). Regarding iFR ≤0.89, the optimal cutoff value of QFR was 0.79 with sensitivity, specificity, and accuracy of 76.3%, 83.3%, and 80.0%, respectively. A 100% sensitivity was observed for a QFR cutoff value of 0.88 and a 100% specificity for a QFR cutoff value of 0.69.

CONCLUSIONS

Our study confirmed good QFR diagnostic performance and correlation with iFR for detecting the functional ischemia caused by intermediate lesions in coronary arteries. However, the pressure wire assessment with iFR might be warranted in 2/3 of patients after QFR assessment.

Physiological benefits evaluated by quantitative flow ratio in patients with reduced left ventricular ejection fraction who underwent percutaneous coronary intervention

BACKGROUND

To explore the clinical benefits of revascularization in patients with different levels of left ventricular ejection fraction (LVEF) from the perspective of quantitative flow ratio (QFR).

METHODS

Patients who underwent successful percutaneous coronary intervention (PCI) and one-year angiographic follow-up were retrospectively screened and computed by QFR analysis. Based on their LVEF, 301 eligible patients were classified into reduced LVEF (≤ 50%, n = 48) and normal LVEF (> 50%, n = 253) groups. Pre-PCI QFR, post-PCI QFR, follow-up QFR, late lumen loss (LLL), LVEF and major adverse cardiovascular and cerebrovascular events (MACCEs) at one year were compared between groups.

RESULTS

The reduced LVEF group had a lower mean pre-PCI QFR than the normal LVEF group (0.67 ± 0.16 vs. 0.73 ± 0.15, p = 0.004), but no significant difference was found in the post-PCI or one-year follow-up QFR. No association was found between LVEF and QFR at pre-PCI or follow-up. The reduced LVEF group had greater increases in QFR (0.27 ± 0.18 vs. 0.22 ± 0.15, p = 0.043) and LVEF (6.05 ± 9.45% vs. - 0.37 ± 8.11%, p < 0.001) than the normal LVEF group. The LLL results showed no difference between the two groups, indicating a similar degree of restenosis. The reduced LVEF group had a higher incidence of MACCEs (14.6% vs. 4.3%, p = 0.016), which was mainly due to the higher risk of heart failure (6.3% vs. 0%, p = 0.004).

CONCLUSION

Compared to the corresponding normal LVEF patients, patients with reduced LVEF who underwent successful PCI were reported to have greater increases in QFR and LVEF, a similar degree of restenosis, and a higher incidence of MACCEs due to a higher risk of heart failure. It seems that patients with reduced LVEF gain more coronary benefits from successful revascularization from the perspective of flow physiology evaluations.

Short- and long-term functional results following drug-coated balloons versus drug- eluting stents in small coronary vessels: The RESTORE quantitative flow ratio study

Background Immediate and long-term functional outcomes after percutaneous treatment of small vessel disease (SVD) with drug-coated balloon (DCB) versus drug-eluting stent (DES) remain unknown. The study sought to investigate whether treatment of de novo SVD with DCB yields similar functional results compared with DES, as judged with angiography-based quantitative flow ratio (QFR). Methods and results QFR was measured at pre-procedural, post-procedural and 9-month angiography in all available subjects from the non-inferiority RESTORE SVD China trial, in which patients were randomized to Restore DCB (n = 116) or Resolute DES (n = 114) study arms. Primary outcome of this analysis was 9-month QFR. Pre-procedural, post-procedural and 9-month QFR was performed in 84.8% (195/230), 83.0% (191/230) and 93.8% (181/193) cases, respectively. At 9 months, the QFR of DCB showed no significant difference to DES (0.88 ± 0.23 vs. 0.92 ± 0.12, p = 0.12). Both 9-month QFR and the QFR difference between post-procedure and 9-month follow-up were correlated with angiographic percentage of diameter stenosis and late loss, and predictive of 2-year clinical outcome. Conclusions Treatment of coronary SVD with DCB resulted in similar 9-month functional results compared with DES. This study provides evidences to the value of QFR as a mean of evaluating device performance after coronary revascularization. Clinical trial registration URL: https://www.clinicaltrials.gov; ClinicalTrial.gov: Identifier: NCT02946307.

Clinical implication of QFR in patients with ST-segment elevation myocardial infarction after drug-eluting stent implantation

The feasibility and prognostic value of quantitative flow ratio (QFR) after percutaneous coronary intervention (PCI) in ST-segment elevation myocardial infarction (STEMI) patients have not been assessed. The aim of this study was to investigate the prognostic utility of post-PCI QFR to predict outcomes in STEMI and determine the influence of functional results, in both culprit and nonculprit lesions, after PCI. Patients undergoing PCI of culprit lesions and receiving staged procedures of nonculprit lesions after 7 days were enrolled from 2 centers and underwent post-PCI QFR. The primary outcome was the vessel-oriented composite endpoints (VOCEs), defined as vessel-related cardiovascular death, vessel-related myocardial infarction, and target vessel revascularization. Four hundred fifteen vessels (186 culprit lesions and 219 nonculprit lesions) in 186 patients were analyzed. Measured at staged PCI, the post-PCI QFR of culprit lesions was significantly lower than that of nonculprit lesions (0.92 ± 0.10 versus 0.95 ± 0.08, p < 0.001). The multivariable model demonstrated that low post-PCI QFR was an independent predictor of 2-year VOCE (20.8% versus 5.7%; hazard ratio 2.718; 95% CI 1.347-5.486; p = 0.005). In STEMI patients with a low angiography-derived index of microcirculatory resistance (≤ 40U), a good correlation and agreement between post-PCI QFR value of culprit lesions at primary and staged procedures (r = 0.942; mean difference: - 0.0017 [- 0.074 to 0.070]) was identified. In conclusion, culprit lesions suffered from suboptimal functional results more frequently compared to nonculprit lesions after PCI in STEMI patients. Low post-PCI QFR was associated with subsequent adverse clinical outcomes. After stenting, culprit lesions may feasibly be assessed through QFR without significant microvascular dysfunction.

Prognostic Value of Quantitative Flow Ratio Based Functional SYNTAX Score in Patients With Left Main or Multivessel Coronary Artery Disease

Background:

The potential impact of quantitative flow ratio (QFR) based functional Synergy Between Percutaneous Coronary Intervention With Taxus and Cardiac Surgery (SYNTAX) score (FSS QFR ) on prognostication and revascularization strategy choice has not been fully investigated, and the discriminant ability of FSS QFR needs further validation.

Methods:

QFR was retrospectively analyzed in left main or patients with multivessel coronary artery disease from the PANDA III trial. A total of 607 patients with analyzable QFR in all vessels were included. FSS QFR was counted by summing the individual scores only in ischemia-producing lesions (vessel QFR ≤0.8). Patients were stratified according to tertiles of SYNTAX score (SS), and 3 groups of FSS were divided by the same cutoff score. The primary end point was 2-year major adverse cardiac events (a composite of cardiac death, any myocardial infarction, or ischemia-driven revascularization).

Results:

After calculating the FSS QFR , 16% (96/607) of study patients moved from higher-risk group by SS to lower-risk group. In the low, intermediate, and high FSS QFR group, the cumulative incidence of 2-year major adverse cardiac events was 9.1%, 13.5%, and 22.3% ( P =0.0004), and the rate of a composite of cardiac death or myocardial infarction (3.8%, 7.3%, and 13.7%, P =0.0006) was also increased. Compared with SS, FSS QFR significantly improved risk classification and prognostication (area under the curve of the receiver-operating characteristics 0.65 versus 0.62, P =0.0009). Moreover, 6% (38/607) of patients, for whom coronary artery bypass grafting would be recommended according to SS, converted to favor percutaneous coronary intervention after FSS QFR calculation. After multivariate adjustment, FSS QFR was an independent predictor of 2-year major adverse cardiac events (adjusted hazard ratio, 1.05 [95% CI, 1.02–1.07]; P =0.0001).

Conclusions:

Among patients with left main or multivessel coronary artery disease, FSS QFR showed applicability in prognostication and revascularization strategy choice. An improved scoring system combining anatomy and physiology (FSS QFR ) discriminated the risk of adverse events modestly better than anatomic assessment (SS) alone.

Registration:

URL: https://www.clinicaltrials.gov . Unique identifier: NCT02017275.

Graphic Abstract:

A graphic abstract is available for this article.