Deferred vs. performed revascularization for coronary stenosis with grey-zone fractional flow reserve values: data from the IRIS-FFR registry

Invasive fractional-flow-reserve prediction by coronary CT angiography using artificial intelligence vs. computational fluid dynamics software in intermediate-grade stenosis

Coronary computed angiography (CCTA) with non-invasive fractional flow reserve (FFR) calculates lesion-specific ischemia when compared with invasive FFR and can be considered for patients with stable chest pain and intermediate-grade stenoses according to recent guidelines. The objective of this study was to compare a new CCTA-based artificial-intelligence deep-learning model for FFR prediction (FFRAI) to computational fluid dynamics CT-derived FFR (FFRCT) in patients with intermediate-grade coronary stenoses with FFR as reference standard. The FFRAI model was trained with curved multiplanar-reconstruction CCTA images of 500 stenotic vessels in 413 patients, using FFR measurements as the ground truth. We included 37 patients with 39 intermediate-grade stenoses on CCTA and invasive coronary angiography, and with FFRCT and FFR measurements in this retrospective proof of concept study. FFRAI was compared with FFRCT regarding the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and diagnostic accuracy for predicting FFR ≤ 0.80. Sensitivity, specificity, PPV, NPV, and diagnostic accuracy of FFRAI in predicting FFR ≤ 0.80 were 91% (10/11), 82% (23/28), 67% (10/15), 96% (23/24), and 85% (33/39), respectively. Corresponding values for FFRCT were 82% (9/11), 75% (21/28), 56% (9/16), 91% (21/23), and 77% (30/39), respectively. Diagnostic accuracy did not differ significantly between FFRAI and FFRCT (p = 0.12). FFRAI performed similarly to FFRCT for predicting intermediate-grade coronary stenoses with FFR ≤ 0.80. These findings suggest FFRAI as a potential non-invasive imaging tool for guiding therapeutic management in these stenoses.

Cardiac Computed Tomography Angiography in CAD Risk Stratification and Revascularization Planning

PURPOSE OF REVIEW

Functional stress testing is frequently used to assess for coronary artery disease (CAD) in symptomatic, stable patients with low to intermediate pretest probability. However, patients with highly vulnerable plaque may have preserved luminal patency and, consequently, a falsely negative stress test. Cardiac computed tomography angiography (CCTA) has emerged at the forefront of primary prevention screening and has excellent agency in ruling out obstructive CAD with high negative predictive value while simultaneously characterizing nonobstructive plaque for high-risk features, which invariably alters risk-stratification and pre-procedural decision making.

RECENT FINDINGS

We review the literature detailing the utility of CCTA in its ability to risk-stratify patients with CAD based on calcium scoring as well as high-risk phenotypic features and to qualify the functional significance of stenotic lesions.

SUMMARY

Calcium scores ≥ 100 should prompt consideration of statin and aspirin therapy. Spotty calcifications < 3 mm, increased non-calcified plaque > 4 mm3 per mm of the vessel wall, low attenuation < 30 HU soft plaque and necrotic core with a rim of higher attenuation < 130 HU, and a positive remodeling index ratio > 1.1 all confer additive risk for acute plaque rupture when present. Elevations in the perivascular fat attenuation index > -70.1 HU are a strong predictor of all-cause mortality and can further the risk stratification of patients in the setting of a non-to-minimal plaque burden. Lastly, a CT-derived fractional flow reserve (FFRCT) < 0.75 or values from 0.76 to 0.80 in conjunction with additional risk factors is suggestive of flow-limiting disease that would benefit from invasive testing. The wealth of information available through CCTA can allow clinicians to risk-stratify patients at elevated risk for an acute ischemic event and engage in advanced revascularization planning.

Instantaneous wave free ratio value impact on left internal mammary artery graft patency

OBJECTIVES

To assess whether instantaneous wave - free ratio (iFR) value is associated with left internal mammary artery (LIMA) graft failure at 12 months follow-up post coronary artery bypass graft (CABG).

BACKGROUND

Data suggests bypass to a non-significant left anterior descending artery (LAD) lesion due to visual over-estimation may lead to LIMA graft failure. Implementing iFR may result in better arterial graft patency.

METHODS

In iCABG (iFR guided CABG) study patients planned to undergo an isolated CABG procedure was prospectively enrolled and iFR was performed for LAD. Coronary computed tomography angiography was performed at 2 and 12 months follow-up. The primary endpoint of this study was to determine the rate of LIMA graft occlusion or hypoperfusion at 2 and 12-months follow-up. We considered a composite secondary endpoint of Major adverse cardiovascular and cerebrovascular event (MACCE) as a secondary outcome.

RESULTS

In total 69 patients were included with no differences regarding age, sex and risk factors. At 2 months, 50 of LIMAs with pre-CABG iFR median 0.855 (0.785 - 0.892) were patent. Hypoperfusion was found in 8 LIMAs (median iFR 0.88 (0.842 - 0.90)). While, 7 LIMAs (median iFR 0.91 (0.88 - 0.96)) were occluded (p = 0.04). At 12 months, when iFR of LAD was >0.85: just 12 (31.6% out of all patent LIMAS) grafts were patent and 24 (100.0% out of all hypoperfused/occluded) grafts were hypoperfused or occluded (p < 0.001). In terms of MACCE, no difference (p = 1.0) was found between all 3 groups divided according to iFR value.

CONCLUSIONS

Instantaneous wave - free ratio value above 0.85 in LAD is a powerful tool predicting LIMA graft failure at 1-year follow up period.

Accuracy and Reproducibility of Coronary Angiography-Derived Fractional Flow Reserve in the Assessment of Coronary Lesion Severity

Purpose

Coronary angiography-derived fractional flow reserve (caFFR) is a novel computational flow dynamics (CFD)-derived assessment of coronary vessel flow with good diagnostic performance. Herein, we performed a retrospective study to evaluate the reproducibility of caFFR findings between observers and investigate the diagnostic performance of caFFR for coronary stenosis defined as FFR ≤0.80, especially in the grey zone (0.75≤caFFR ≤0.80).

Patients and Methods

A total of 150 patients (167 coronary vessels) underwent caFFR (with FlashAngio used for calculation of flow variables) and subsequent invasive fractional flow reserve (FFR) measurements. Outcomes, including reproducibility, were compared for vessels in and outside the grey zone.

Results

The correlation of caFFR findings was good between the two laboratories (r = 0.723, p<0.001). The AUC of ROC were both high for caFFR-CoreLab1 and caFFR-CoreLab2 (0.975 and 0.883). The diagnostic accuracy, sensitivity, specificity, and negative and positive predictive values were not significantly different between the two laboratories (p>0.05). caFFR had a strong correlation with measures to FFR (r=0.911, p<0.001). There was no systematic difference between caFFR and FFR on Bland-Altman analysis in and outside the grey zone. There was no difference in diagnostic accuracy between the grey and non-grey zones in the prediction of FFR ≤0.80 (p=0.09).

Conclusion

The inter-observer reproducibility for caFFR was high, and the diagnostic accuracy of caFFR was good compared to that of FFR.

Analysis identifying minimal governing parameters for clinically accurate in silico fractional flow reserve

Background

Personalized hemodynamic models can accurately compute fractional flow reserve (FFR) from coronary angiograms and clinical measurements (FFR baseline ), but obtaining patient-specific data could be challenging and sometimes not feasible. Understanding which measurements need to be patient-tuned vs. patient-generalized would inform models with minimal inputs that could expedite data collection and simulation pipelines.

Aims

To determine the minimum set of patient-specific inputs to compute FFR using invasive measurement of FFR (FFR invasive ) as gold standard.

Materials and Methods

Personalized coronary geometries ( N = 50 ) were derived from patient coronary angiograms. A computational fluid dynamics framework, FFR baseline , was parameterized with patient-specific inputs: coronary geometry, stenosis geometry, mean arterial pressure, cardiac output, heart rate, hematocrit, and distal pressure location. FFR baseline was validated against FFR invasive and used as the baseline to elucidate the impact of uncertainty on personalized inputs through global uncertainty analysis. FFR streamlined was created by only incorporating the most sensitive inputs and FFR semi-streamlined additionally included patient-specific distal location.

Results

FFR baseline was validated against FFR invasive via correlation ( r = 0.714 , p < 0.001 ), agreement (mean difference: 0.01 ± 0.09 ), and diagnostic performance (sensitivity: 89.5%, specificity: 93.6%, PPV: 89.5%, NPV: 93.6%, AUC: 0.95). FFR semi-streamlined provided identical diagnostic performance with FFR baseline . Compared to FFR baseline vs. FFR invasive , FFR streamlined vs. FFR invasive had decreased correlation ( r = 0.64 , p < 0.001 ), improved agreement (mean difference: 0.01 ± 0.08 ), and comparable diagnostic performance (sensitivity: 79.0%, specificity: 90.3%, PPV: 83.3%, NPV: 87.5%, AUC: 0.90).

Conclusion

Streamlined models could match the diagnostic performance of the baseline with a full gamut of patient-specific measurements. Capturing coronary hemodynamics depended most on accurate geometry reconstruction and cardiac output measurement.

Effect of Atorvastatin on Serial Changes in Coronary Physiology and Plaque Parameters

BACKGROUND

The effects of statin on coronary physiology have not been well evaluated.

OBJECTIVES

The authors performed this prospective study to investigate changes in coronary flow indexes and plaque parameters, and their associations with atorvastatin therapy in patients with coronary artery disease (CAD).

METHODS

Ninety-five patients with intermediate CAD who received atorvastatin therapy underwent comprehensive physiological assessments with fractional flow reserve (FFR), coronary flow reserve, index of microcirculatory resistance, and intravascular ultrasound at the index procedure, and underwent the same evaluations at 12-month follow-up. Optimal low-density lipoprotein cholesterol (LDL-C) was defined as LDL-C <70 mg/dL or ≥50% reduction from the baseline. The primary endpoint was a change in the FFR.

RESULTS

Baseline FFR, minimal lumen area, and percent atheroma volume (PAV) were 0.88 ± 0.05, 3.87 ± 1.28, 55.92 ± 7.30, respectively. During 12 months, the percent change in LDL-C was -33.2%, whereas FFR was unchanged (0.87 ± 0.06 at 12 months; P = 0.694). Vessel area, lumen area, and PAV were significantly decreased (all P values <0.05). The achieved LDL-C level and the change of PAV showed significant inverse correlations with the change in FFR. In patients with optimally modified LDL-C, the FFR had increased (0.87 ± 0.06 vs 0.89 ± 0.07; P = 0.014) and the PAV decreased (56.81 ± 6.44% vs 55.18 ± 8.19%; P = 0.031), whereas in all other patients, the FFR had decreased (0.88 ± 0.05 vs 0.86 ± 0.06; P = 0.025) and the PAV remained unchanged.

CONCLUSIONS

In patients with CAD, atorvastatin did not change FFR despite a decrease in the PAV. However, in patients who achieved the optimal LDL-C target level with atorvastatin, the FFR had significantly increased with decrease of the PAV. (Effect of Atorvastatin on Fractional Flow Reserve in Coronary Artery Disease [FORTE]; NCT01946815).

Influence of intensive lipid-lowering on CT derived fractional flow reserve in patients with stable chest pain: Rationale and design of the FLOWPROMOTE study

INTRODUCTION

Coronary CT angiography (CTA) derived fractional flow reserve (FFR_CT ) shows high diagnostic performance when compared to invasively measured FFR. Presence and extent of low attenuation plaque density have been shown to be associated with abnormal physiology by measured FFR. Moreover, it is well established that statin therapy reduces the rate of plaque progression and results in morphology alterations underlying atherosclerosis. However, the interplay between lipid lowering treatment, plaque regression, and the coronary physiology has not previously been investigated.

AIM

To test whether lipid lowering therapy is associated with significant improvement in FFR_CT , and whether there is a dose-response relationship between lipid lowering intensity, plaque regression, and coronary flow recovery.

METHODS

Investigator driven, prospective, multicenter, randomized study of patients with stable angina, coronary stenosis ≥50% determined by clinically indicated first-line CTA, and FFR_CT  ≤ 0.80 in whom coronary revascularization was deferred. Patients are randomized to standard (atorvastatin 40 mg daily) or intensive (rosuvastatin 40 mg + ezetimibe 10 mg daily) lipid lowering therapy for 18 months. Coronary CTA scans with blinded coronary plaque and FFR_CT analyses will be repeated after 9 and 18 months. The primary endpoint is the 18-month difference in FFR_CT using (1) the FFR_CT value 2 cm distal to stenosis and (2) the lowest distal value in the vessel of interest. A total of 104 patients will be included in the study.

CONCLUSION

The results of this study will provide novel insights into the interplay between lipid lowering, and the pathophysiology in coronary artery disease.

Comparison of adenosine-independent pressure indices to fractional flow reserve in stent-jailed bifurcation side branches

OBJECTIVES AND BACKGROUND

This study aims to evaluate whether the high correlation and classification agreement of the instantaneous wave-free ratio (iFR) and the resting distal coronary to aortic pressure ratio (P_d /P_a ) with the fractional flow reserve (FFR) can be confirmed in stent-jailed side branches (J-SB).

METHODS

Consecutive patients (n = 49) undergoing provisional stenting were prospectively enrolled and a physiological assessment of the J-SB (n = 51) was performed. FFR, iFR, and P_d /P_a were measured and the hemodynamic relevance was determined using cutoff values of ≤0.80, ≤0.89, and ≤0.92, respectively.

RESULTS

Both iFR (r = 0.75) and P_d /P_a (r = 0.77) correlated closely with FFR. Classification agreement with FFR was 78% for iFR (81% sensitivity, 77% specificity) and 75% for P_d /P_a (63% sensitivity and 80% specificity). However, angiographic diameter stenosis and pressure indices correlated poorly. For a threshold of ≥70% stenosis, agreement concerning hemodynamic relevance was found in 59% for FFR, 69% for iFR, and 61% for P_d /P_a .

CONCLUSION

As reported for other lesion types, FFR and the adenosine-independent pressure indices iFR and P_d /P_a show close correlation and a high classification agreement of approximately 75%-80% in J-SB. Therefore, iFR can be regarded as a recommendable alternative to FFR for the guidance of provisional stenting in bifurcation lesions.

Differential Prognostic Value of Revascularization for Coronary Stenosis With Intermediate FFR by Coronary Flow Reserve

OBJECTIVES

The authors sought to evaluate comparative prognosis between deferred versus performed percutaneous coronary intervention (PCI) according to coronary flow reserve (CFR) values of patients with intermediate fractional flow reserve (FFR).

BACKGROUND

For coronary stenosis with intermediate FFR, the prognostic value of PCI remains controversial. The prognostic impact of PCI may be different according to CFR in patients with intermediate FFR.

METHODS

From the ILIAS Registry (Inclusive Invasive Physiological Assessment in Angina Syndromes Registry, N = 2,322), 400 patients (412 vessels) with intermediate FFR (0.75-0.80) were selected. Patients were stratified into preserved CFR (>2.0, n = 253) and depressed CFR (≤2.0, n = 147) cohorts. Per-vessel clinical outcomes during 5 years of follow-up were compared between deferred versus performed PCI groups in both cohorts. The primary outcome was target vessel failure (TVF), a composite of cardiac death, target vessel myocardial infarction, or target vessel revascularization.

RESULTS

Among the study population, PCI was deferred for 210 patients (219 vessels, 53.2%) (deferred group) and performed for 190 patients (193 vessels, 46.8%) (performed group). The risk of TVF was comparable between the deferred and performed groups (12.8% vs 14.2%; adjusted HR: 1.403; 95% CI: 0.584-3.369; P = 0.448). When stratified by CFR, PCI was performed in 39.1% (100/261 vessels) of the preserved CFR cohort and 61.9% (93/151 vessels) of the depressed CFR cohort. Within the preserved CFR cohort, the risk of TVF did not differ significantly between the deferred and performed groups (11.0% vs 13.9%; adjusted HR: 0.770; 95% CI: 0.262-2.266; P = 0.635). However, in the depressed CFR cohort, the deferred group had a significantly higher risk of TVF than the performed group (17.2% vs 14.2%; adjusted HR: 4.932; 95% CI: 1.312-18.53; P = 0.018). A significant interaction was observed between CFR and the treatment decision (interaction P = 0.049). Results were consistent after inverse probability weighting adjustment.

CONCLUSIONS

In patients with intermediate FFR of 0.75 to 0.80, the prognostic value of PCI differed according to CFR, with a significant interaction. PCI was associated with a lower risk of TVF compared with the deferral strategy when CFR was depressed (≤2.0), but there was no difference when CFR was preserved (>2.0). CFR could be used as an additional risk stratification tool to determine treatment strategies in patients with intermediate FFR. (Inclusive Invasive Physiological Assessment in Angina Syndromes Registry [ILIAS Registry]; NCT04485234).

CT Fractional Flow Reserve: A Practical Guide to Application, Interpretation, and Problem Solving

CT fractional flow reserve (FFR_CT) is a physiologic simulation technique that models coronary flow from routine coronary CT angiography (CTA). To evaluate lesion-specific ischemia, FFR_CT is measured 2 cm distal to a stenotic lesion. FFR_CT greater than 0.8 is normal, 0.76-0.8 is borderline, and 0.75 or less is abnormal. FFR_CT should always be interpreted in correlation with clinical and anatomic coronary CTA findings. FFR_CT increases the specificity of coronary CTA in the evaluation of coronary artery disease, decreases the prevalence of nonobstructive disease in invasive coronary angiography (ICA), and helps with revascularization decisions and planning. Patients with intermediate-risk coronary anatomy at CTA and abnormal FFR_CT can undergo ICA and revascularization, whereas those with normal FFR_CT can be safely deferred from ICA. In borderline FFR_CT values, management is decided in the context of the clinical scenario, but many cases could be safely managed with medical treatment. There are some limitations and pitfalls of FFR_CT. Abnormal FFR_CT values can be seen in mild stenosis, and normal FFR_CTvalues can be seen in severe stenosis. Gradually decreasing or abnormal low FFR_CT values at the distal vessel without a proximal focal lesion could be due to diffuse atherosclerosis. Coronary stents, bypass grafts, coronary anomalies, coronary dissection, transcatheter aortic valve replacement, unstable angina, and acute or recent myocardial infarction are situations in which FFR_CT has not been validated and should not be used at this time. The authors provide a practical guide to the applications and interpretation of FFR_CT, focusing on common pitfalls and challenges. Online supplemental material is available for this article. ^©RSNA, 2022.

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.

Non-randomized comparison between revascularization and deferral for intermediate coronary stenosis with abnormal fractional flow reserve and preserved coronary flow reserve

Limited data are available regarding comparative prognosis after percutaneous coronary intervention (PCI) versus deferral of revascularization in patients with intermediate stenosis with abnormal fractional flow reserve (FFR) but preserved coronary flow reserve (CFR). From the International Collaboration of Comprehensive Physiologic Assessment Registry (NCT03690713), a total of 330 patients (338 vessels) who had coronary stenosis with FFR ≤ 0.80 but CFR > 2.0 were selected for the current analysis. Patient-level clinical outcome was assessed by major adverse cardiac events (MACE) at 5 years, a composite of all-cause death, target-vessel myocardial infarction (MI), or target-vessel revascularization. Among the study population, 231 patients (233 vessels) underwent PCI and 99 patients (105 vessels) were deferred. During 5 years of follow-up, cumulative incidence of MACE was 13.0% (31 patients) without significant difference between PCI and deferred groups (12.7% vs. 14.0%, adjusted HR 1.301, 95% CI 0.611-2.769, P = 0.495). Multiple sensitivity analyses by propensity score matching and inverse probability weighting also showed no significant difference in patient-level MACE and vessel-specific MI or revascularization. In this hypothesis-generating study, there was no significant difference in clinical outcomes between PCI and deferred groups among patients with intermediate stenosis with FFR ≤ 0.80 but CFR > 2.0. Further study is needed to confirm this finding.Clinical Trial Registration: International Collaboration of Comprehensive Physiologic Assessment Registry (NCT03690713; registration date: 10/01/2018).

Resting distal to aortic pressure ratio and fractional flow reserve discordance affects the diagnostic performance of quantitative flow ratio: Results from an individual patient data meta-analysis

OBJECTIVE

To evaluate the diagnostic performance of quantitative flow ratio (QFR) related to fractional flow reserve (FFR) and resting distal-to-aortic pressure ratio (resting Pd/Pa) concordance.

BACKGROUND

QFR is a method for computation of FFR based on standard coronary angiography. It is unclear how QFR is performed in patients with discordance between FFR and resting pressure ratios (distal-to-aortic pressure ratio [Pd/Pa]).

MATERIALS AND METHODS

The main comparison was the diagnostic performance of QFR with FFR as reference stratified by correspondence between FFR and resting Pd/Pa. Secondary outcome measures included distribution of clinical or procedural characteristics stratified by FFR and resting Pd/Pa correspondence.

RESULTS

Four prospective studies matched the inclusion criteria. Analysis was performed on patient level data reaching a total of 759 patients and 887 vessels with paired FFR, QFR, and resting Pd/Pa. Median FFR was 0.85 (IQR: 0.77-0.90). Diagnostic accuracy of QFR with FFR as reference was higher if FFR corresponded to resting Pd/Pa: accuracy 90% (95% CI: 88-92) versus 72% (95% CI: 64-80), p < .001, and sAUC 0.95 (95% CI: 0.92-0.96) versus 0.73 (95% CI: 0.69-0.77), p < .001. Resting Pd/Pa and FFR discordance were related to age, sex, hypertension, and lesion severity.

CONCLUSION

Diagnostic performance of QFR with FFR as reference is reduced for lesions with discordant FFR (≤0.80) and resting Pd/Pa (≤0.92) measurements.

Safety and Long-Term Clinical Outcomes of Fractional Flow Reserve Guided Coronary Revascularisation

BACKGROUND

Increasingly, fractional flow reserve (FFR) is employed to assess coronary artery stenoses although there is limited real world long-term outcome data with a recent report questioning its safety. This study aimed to assess the in-hospital complications and clinical outcomes up to 10 years after FFR-guided revascularisation at a tertiary Australian hospital.

METHODS

The cohort comprised 274 consecutive patients undergoing FFR from 2010 to 2015 with follow-up to 2020. In-hospital complications and long-term outcomes were compared between patients with FFR≤0.80 and FFR>0.80. Major adverse cardiac events (MACE) comprised cardiac death, myocardial infarction (MI) and target vessel revascularisation (TVR).

RESULTS

The FFR was ≤0.80 in 166 and >0.80 in 108 patients. Stable coronary disease was present in 95%. Revascularisation was undertaken in 86.7% of the FFR≤0.80 group and in 2.8% of the group with an FFR>0.80. In-hospital adverse events were 3.3% with no pressure wire-related coronary dissection, stroke or death. At median follow-up of 5 years, patients with FFR≤0.80 and FFR>0.80 had a similar rate of cardiac death (2.6% versus 5.0%, p=0.335) and MI (2.6% versus 6.9%, p=0.154). In the FFR>0.80 group, MACE (17.8% v 7.9%; p=0.018) and TVR (12.9% v 5.3%; p=0.033) were significantly higher.

CONCLUSION

This observational study highlights the safety and long-term effectiveness of FFR-guided coronary revascularisation in patients with predominantly stable disease.

Physiology-Based Revascularization of Left Main Coronary Artery Disease

It is of critical importance to correctly assess the significance of a left main lesion. Underestimation of significance beholds the risk of inappropriate deferral of revascularization, whereas overestimation may trigger major but unnecessary interventions. This article addresses the invasive physiological assessment of left main disease and its role in deciding upon revascularization. It mainly focuses on the available evidence for fractional flow reserve and instantaneous wave-free ratio, their interpretation, and limitations. We also discuss alternative invasive physiological indices and imaging, as well as the link between physiology, ischemia, and prognosis.

Prognostic Value of Prerevascularization Fractional Flow Reserve Mediated by the Postrevascularization Level

IMPORTANCE

The prognostic value of pre-percutaneous coronary intervention (PCI) fractional flow reserve (FFR) may be associated with the post-PCI FFR and their interaction. To correctly interpret the prognostic value of pre-PCI FFR, it is essential to understand to what extent the association of pre-PCI FFR with clinical outcomes is explained by post-PCI FFR.

OBJECTIVE

To investigate the extent to which post-PCI FFR mediates the association of pre-PCI FFR with vessel-related outcomes using an international, multicenter collaboration registry.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study used pooled patient data from 4 international FFR registries. A total of 1488 patients with pre-PCI FFR of 0.80 or less who underwent elective PCI were included. Data collection was conducted from November 2011 to August 2019, and analysis was conducted from September 2019 to July 2020.

MAIN OUTCOMES AND MEASURES

The primary outcome was target vessel failure (TVF) during 2 years of follow-up. The extent to which post-PCI FFR of less than 0.90 mediated the association of pre-PCI FFR less than 0.75 (vs pre-PCI FFR of 0.75 or greater) with TVF was evaluated using a mediation analysis in a counterfactual framework.

RESULTS

Among 1488 patients, the mean (SD) age was 63.5 (9.9) years and 1161 patients (78.0%) were men. The median (interquartile range) pre-PCI and post-PCI FFR were 0.71 (0.62-0.76) and 0.88 (0.83-0.92), respectively. The direct association of low pre-PCI FFR (ie, <0.75) with TVF was significant (odds ratio, 1.81; 95% CI, 1.03-3.17; P = .04), while the mediation by post-PCI FFR level of less than 0.90 was not (indirect association: odds ratio, 1.03; 95% CI, 0.98-1.09; P = .24). In sensitivity analyses using several pre-PCI cutoffs, the mediations by post-PCI FFR were consistently weak.

CONCLUSIONS AND RELEVANCE

In this study, the association of pre-PCI FFR with TVF was not significantly mediated by post-PCI FFR. Poor prognosis due to progressed atherosclerosis, represented as low FFR, may not be reversed by successful PCI that increases FFR. Therefore, the prognostic value of pre-PCI FFR may mainly reflect the global atherosclerotic burden, not the extent of the modifiable epicardial stenosis.

Sex Differences in Coronary Computed Tomography Angiography-Derived Fractional Flow Reserve: Lessons From ADVANCE

OBJECTIVES

This study is to determine the management and clinical outcomes of patients investigated with coronary computed tomography angiography (CCTA)-derived fractional flow reserve (FFR_CT) according to sex.

BACKGROUND

Women are underdiagnosed with conventional ischemia testing, have lower rates of obstructive coronary artery disease (CAD) at invasive coronary angiography (ICA), yet higher mortality compared to men. Whether FFR_CT improves sex-based patient management decisions compared to CCTA alone is unknown.

METHODS

Subjects with symptoms and CAD on CCTA were enrolled (2015 to 2017). Demographics, symptom status, CCTA anatomy, coronary volume to myocardial mass ratio (V/M), lowest FFR_CT values, and management plans were captured. Endpoints included reclassification rate between CCTA and FFR_CT management plans, incidence of ICA demonstrating obstructive CAD (≥50% stenosis) and revascularization rates.

RESULTS

A total of 4,737 patients (n = 1,603 females, 33.8%) underwent CCTA and FFR_CT. Women were older (age 68 ± 10 years vs. 65 ± 10 years; p < 0.0001) with more atypical symptoms (41.5% vs. 33.9%; p < 0.0001). Women had less obstructive CAD (65.4% vs. 74.7%; p < 0.0001) at CCTA, higher FFR_CT (0.76 ± 0.10 vs. 0.73 ± 0.10; p < 0.0001), and lower likelihood of positive FFR_CT ≤ 0.80 for the same degree stenosis (p < 0.0001). A positive FFR_CT ≤0.80 resulted in equal referral to ICA (n = 510 [54.5%] vs. n = 1,249 [56.5%]; p = 0.31), but more nonobstructive CAD (n = 208 [32.1%] vs. n = 354 [24.5%]; p = 0.0003) and less revascularization (n = 294 [31.4%] vs. n = 800 [36.2%]; p < 0.0001) in women, unless the FFR_CT was ≤0.75 where revascularization rates were similar (n = 253 [41.9%] vs. n = 715 [46.4%]; p = 0.06). Women have a higher V/M ratio (26.17 ± 7.58 mm³/g vs. 24.76 ± 7.22 mm³/g; p < 0.0001) that is associated with higher FFR_CT independent of degree stenosis (p < 0.001). Predictors of revascularization included stenosis severity, FFR_CT, symptoms, and V/M ratio (p < 0.001) but not female sex (p = 0.284).

CONCLUSIONS

FFR_CT differs between the sexes, as women have a higher FFR_CT for the same degree of stenosis. In FFR_CT-positive CAD, women have less obstructive CAD at ICA and less revascularization, which is associated with higher V/M ratio. The findings suggest that CAD and FFR_CT variations by sex need specific interpretation as these differences may affect therapeutic decision making and clinical outcomes. (Assessing Diagnostic Value of Non-invasive FFRCT in Coronary Care [ADVANCE]; NCT02499679).

Physiological Pattern of Disease Assessed by Pressure-Wire Pullback Has an Influence on Fractional Flow Reserve/Instantaneous Wave-Free Ratio Discordance

BACKGROUND

Fractional flow reserve (FFR) and instantaneous wave-free ratio (iFR) disagree on the hemodynamic significance of a coronary lesion in ≈20% of cases. It is unknown whether the physiological pattern of disease is an influencing factor for this. This study assessed whether the physiological pattern of coronary artery disease influences discordance between FFR and iFR measurement.

METHODS AND RESULTS

Three-hundred and sixty intermediate coronary lesions (345 patients; mean age, 64.4±10.3 years; 76% men) with combined FFR, iFR, and iFR pressure-wire pullback were included for analysis from an international multicenter registry. Cut points for hemodynamic significance were FFR ≤0.80 and iFR ≤0.89, respectively. Lesions were classified into FFR+/iFR+ (n=154; 42.7%), FFR-/iFR+ (n=38; 10.6%), FFR+/iFR- (n=41; 11.4%), and FFR-/iFR- (n=127; 35.3%) groups. The physiological pattern of disease was classified according to the iFR pullback recordings as predominantly physiologically focal (n=171; 47.5%) or predominantly physiologically diffuse (n=189; 52.5%). Median FFR and iFR were 0.80 (interquartile range, 0.75-0.85) and 0.89 (interquartile range, 0.86-0.92), respectively. FFR disagreed with iFR in 22% (79 of 360). The physiological pattern of disease was the only influencing factor relating to FFR/iFR discordance: predominantly physiologically focal was significantly associated with FFR+/iFR- (58.5% [24 of 41]), and predominantly physiologically diffuse was significantly associated with FFR-/iFR+ (81.6% [31 of 38]; P<0.001 for pattern of disease between FFR+/iFR- and FFR-/iFR+ groups).

CONCLUSIONS

The physiological pattern of coronary artery disease was an important influencing factor for FFR/iFR discordance.

Prognostic Value of Resting Distal-to-Aortic Coronary Pressure in Clinical Practice

BACKGROUND

The resting distal-to-aortic coronary pressure ratio (Pd/Pa) is a universally available, hyperemia-free physiological index of coronary stenosis. We investigated clinical outcomes according to resting Pd/Pa versus hyperemic fractional flow reserve (FFR).

METHODS

From the IRIS-FFR (Interventional Cardiology Research Incooperation Society Fractional Flow Reserve) registry, 7014 lesions in 4707 patients with valid resting Pd/Pa and FFR were included in this study. The primary outcome was major adverse cardiac events (MACE; a composite of cardiac death, myocardial infarction, and repeat intervention). The MACE rate was compared among resting Pd/Pa ≤0.92 and FFR ≤0.80. A marginal Cox model accounted for correlated data in patients with multiple lesions.

RESULTS

During a median follow-up of 2.0 years, 223 MACEs occurred. Resting Pd/Pa was an independent predictor for the occurrence of MACE (adjusted hazard ratio [aHR], 1.89 [95% CI, 1.32-2.71]; P=0.001) over clinical and angiographic variables. When resting Pd/Pa and FFR were added into a multivariable model, MACE was no longer significantly associated with resting Pd/Pa (aHR, 1.35 [95% CI, 0.93-1.97]; P=0.12) but remained to be associated with FFR (aHR, 2.34 [95% CI, 1.56-3.54]; P<0.001). Compared with lesions with normal value of resting Pa/Pa and FFR, lesions with abnormal values of either resting Pd/Pa (aHR, 2.12 [95% CI, 1.17-3.84]; P=0.014) or FFR (aHR, 2.32 [95% CI, 1.52-3.55]; P<0.001) or both (aHR, 2.37 [95% CI, 1.57-3.57]; P<0.001) showed a significantly increased risk of the occurrence of MACE.

CONCLUSIONS

Resting Pd/Pa appeared to be a less-robust prognostic index than FFR. Resting Pd/Pa could be used as a prognostic index when hyperemic agents are contraindicated or not easily available. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT01366404.

Percutaneous coronary intervention versus medical therapy in patients with angina and grey-zone fractional flow reserve values: a randomised clinical trial

INTRODUCTION

There is conflicting evidence regarding the benefits of percutaneous coronary intervention (PCI) in patients with grey zone fractional flow reserve (^GZFFR artery) values (0.75-0.80). The prevalence of ischaemia is unknown. We wished to define the prevalence of ischaemia in ^GZFFR artery and assess whether PCI is superior to optimal medical therapy (OMT) for angina control.

METHODS

We enrolled 104 patients with angina with 1:1 randomisation to PCI or OMT. The artery was interrogated with a Doppler flow/pressure wire. Patients underwent Magnetic Resonance Imaging (MRI) with follow-up at 3 and 12 months. The primary outcome was angina status at 3 months using the Seattle Angina Questionnaire (SAQ).

RESULTS

104 patients (age 60±9 years), 79 (76%) males and 79 (76%) Left Anterior Descending (LAD) stenoses were randomised. Coronary physiology and SAQ were similar. Of 98 patients with stress perfusion MRI data, 17 (17%) had abnormal perfusion (≥2 segments with ≥25% ischaemia or ≥1 segment with ≥50% ischaemia) in the target ^GZFFR artery. Of 89 patients with invasive physiology data, 26 (28%) had coronary flow velocity reserve <2.0 in the target ^GZFFR artery. After 3 months of follow-up, compared with patients treated with OMT only, patients treated by PCI and OMT had greater improvements in SAQ angina frequency (21 (28) vs 10 (23); p=0.026) and quality of life (24 (26) vs 11 (24); p=0.008) though these differences were no longer significant at 12 months.

CONCLUSIONS

Non-invasive evidence of major ischaemia is uncommon in patients with ^GZFFR artery. Compared with OMT alone, patients randomised to undergo PCI reported improved symptoms after 3 months but these differences were no longer significant after 12 months.

TRIAL REGISTRATION NUMBER

NCT02425969.

Outcomes With Deferred Versus Performed Revascularization of Coronary Lesions With Gray-Zone Fractional Flow Reserve Values

BACKGROUND

Management of coronary lesions with fractional flow reserve values in the gray zone (0.75-0.80) remains controversial due to conflicting data on the performance versus deferral of revascularization.

METHODS

We performed a systematic review and meta-analysis of 7 observational studies including 2683 patients that compared the outcomes of deferred versus performed revascularization of coronary lesions with gray-zone fractional flow reserve values.

RESULTS

During a mean follow-up of 31±9 months, the incidence of major adverse cardiovascular events (12.54 % versus 11.25%; odds ratio [OR], 1.64 [95% CI, 0.78-3.44]; P=0.19, I2=84%), cardiac mortality (1.25% versus 0.72%; OR, 1.78 [95% CI, 0.58-5.46]; P=0.31, I2=18%), and myocardial infarction (1.28% versus 2.66%; OR, 0.79 [95% CI, 0.22-2.79]; P=0.71, I2=65%) was similar with deferral versus performance of revascularization in coronary lesions with gray-zone fractional flow reserve. Deferral of revascularization was associated with a higher incidence of target vessel revascularization (9.12% versus 5.78%; OR, 1.85 [95% CI, 1.03-3.33]; P=0.04, I2=62%). When the analysis was limited only to studies that used percutaneous coronary intervention for revascularization, deferred revascularization remained associated with a higher risk of target vessel revascularization (18% versus 7.3%; OR, 3.04 [95% CI, 1.53-6.02]; P<0.001) and was associated with a higher risk of major adverse cardiovascular event (23.2% versus 13.4%; OR, 3.38 [95% CI, 1.92-5.95]; P<0.001).

CONCLUSIONS

In lesions with gray-zone fractional flow reserve, revascularization was associated with a similar incidence of major adverse cardiovascular event but a lower incidence of target vessel revascularization over a mean follow-up of approximately 2.5 years.

CLINICAL TRIAL REGISTRATION

URL: https://www.crd.york.ac.uk/prospero/. Unique identifier: CRD42019128076.

Revisiting the Optimal Fractional Flow Reserve and Instantaneous Wave-Free Ratio Thresholds for Predicting the Physiological Significance of Coronary Artery Disease

BACKGROUND

There has been a gradual upward creep of revascularization thresholds for both fractional flow reserve (FFR) and instantaneous wave-free ratio (iFR), before the clinical outcome trials for both indices. The increase in revascularization that has potentially resulted is at odds with increasing evidence questioning the benefits of revascularizing stable coronary disease. Using an independent invasive reference standard, this study primarily aimed to define optimal thresholds for FFR and iFR and also aimed to compare the performance of iFR, FFR, and resting distal coronary pressure (Pd)/central aortic pressure (Pa).

METHODS AND RESULTS

Pd and Pa were measured in 75 patients undergoing coronary angiography±percutaneous coronary intervention with resting Pd/Pa, iFR, and FFR calculated. Doppler average peak flow velocity was simultaneously measured and hyperemic stenosis resistance calculated as hyperemic stenosis resistance=Pa-Pd/average peak flow velocity (using hyperemic stenosis resistance >0.80 mm Hg/cm per second as invasive reference standard). An FFR threshold of 0.75 had an optimum diagnostic accuracy (84%), whereas for iFR this was 0.86 (76%). At these thresholds, the discordance in classification between indices was 11%. The accuracy of contemporary thresholds (FFR, 0.80; iFR, 0.89) was significantly lower (78.7% and 65.3%, respectively) with a 25% rate of discordance. The optimal threshold for Pd/Pa was 0.88 (77.3% accuracy). When comparing indices at optimal thresholds, FFR showed the best diagnostic performance (area under the curve, 0.91 FFR versus 0.79 iFR and 0.77 Pd/Pa, P=0.002).

CONCLUSIONS

Contemporary thresholds provide suboptimal diagnostic accuracy compared with an FFR threshold of 0.75 and iFR threshold of 0.86 (cutoffs in derivation studies). Whether more rigorous thresholds would result in selecting populations gaining greater symptom and prognostic benefit needs assessing in future trials of physiology-guided revascularization.

Deferral Versus Performance of Revascularization for Coronary Stenosis With Grey Zone Fractional Flow Reserve Values: A Systematic Review and Meta-Analysis

We searched PubMed, EMBASE, Cochrane Library, and Web of Science for studies using fractional flow reserve (FFR) to determine whether revascularization should be performed or deferred for patients with coronary stenosis and grey zone FFR. Meta-analysis was performed using the generic inverse variance method, and hazard ratios (HR) were synthesized with a random-effects model. Of 2766 records, 7 nonrandomized studies including 2683 patients were selected. The pooled results demonstrated, during a median follow-up of 32 months, that revascularization significantly reduced the risk of major adverse cardiac events (MACE; 7 studies: HR [95% confidence interval, CI]: 0.65 [0.45-0.93], P = .02) and target vessel revascularization (TVR; 4 studies: HR [95% CI]: 0.52 [0.36-0.76], P < .01). Whereas revascularization was not significantly superior in terms of all-cause death (3 studies: HR [95% CI]: 0.56 [0.26-1.22], P = .14), cardiac death (2 studies: HR [95% CI]: 0.57 [0.16-2.01], P = .38), myocardial infarction (MI; 4 studies: HR [95% CI]: 1.03 [0.26-4.03]), and all-cause death or MI (3 studies: HR [95% CI]: 0.66 [0.20-2.19], P = .50). Therefore, revascularization appeared to be superior to deferral for patients with grey zone FFR in MACE and TVR, while hard end points did not show such significance. This work was registered in PROSPERO (CRD42019118432).

Optimal Treatment Strategy for Coronary Artery Stenoses with Grey Zone Fractional Flow Reserve Values. A Systematic Review and Meta-Analysis

OBJECTIVES

We conducted a review and meta-analysis of published data to compare revascularization to deferral strategy for coronary lesions with grey zone fractional flow reserve (FFR).

BACKGROUND

Optimal treatment for coronary stenoses with FFR values between 0.75 and 0.80, the so-called grey zone, remains a matter of debate.

METHODS

We included all studies evaluating revascularization versus deferral for lesions with grey zone FFR. The primary outcome was study-defined major adverse cardiac events (MACE). Secondary outcomes were the composite of death or MI and target vessel revascularization (TVR). A total of 2362 patients were included, of whom 1181 underwent revascularization (revascularization group) and 1181 received medical treatment only (deferral group).

RESULTS

After a mean follow-up period of 2.4 years, no difference was found for the primary outcome of the study-defined MACE between the two groups [RR = 1.33 (0.73-2.44), p = 0.35]. In addition, there was no difference for the secondary outcomes of death or MI and TVR between the two groups [RR = 1.39 (0.56-3.47), p = 0.48 and RR = 1.49 (0.89-2.51), p = 0.13, respectively].

CONCLUSIONS

In this meta-analysis revascularization of coronary stenoses with grey zone FFR showed no advantage over a deferral strategy in terms of study-defined MACE. Case by case judgment should be implemented to guide treatment in this special subset of patients.

Daily risk of adverse outcomes in patients undergoing complex lesions revascularization: A subgroup analysis from the RAIN-CARDIOGROUP VII study (veRy thin stents for patients with left mAIn or bifurcatioN in real life)

INTRODUCTION

Percutaneous coronary intervention (PCI) for complex lesions, including unprotected left main (ULM) and bifurcations, is gaining a relevant role in treating coronary artery disease with good outcomes, also thanks to new generation stents. The daily risk of adverse cardiovascular events and their temporal distribution after these procedures is not known.

METHODS

All consecutive patients presenting with a critical lesion of ULM or bifurcation treated with very thin struts stents, enrolled in the RAIN-Cardiogroup VII study, were analyzed. The daily risk of major acute cardiovascular events (MACE), target lesion revascularization (TLR) and stent thrombosis (ST) and their temporal distribution in the first year of follow-up was the primary endpoint. Differences among subgroups (ULM, patient presentation, kind of stent polymer) were the secondary endpoint.

RESULTS

2745 patients were included, mean age 68 ± 11 years, 33.3% diabetics, 54.5% had an acute coronary syndrome (ACS); 88.5% of treated lesions were bifurcations, 27.2% ULM. Average daily risk was 0.022% for MACE, 0.005% for TLR and 0.004% for ST, in the first year. Bimodal distribution of adverse events, especially TLR, with an early peak in the first 50 days and a late one after 150 days, was observed. Patients with ULM presented a significantly higher daily risk of events, and ACS patients presented higher MACE risk. No difference emerged according to the type of stent polymer.

CONCLUSIONS

The daily risk of adverse events in the first year after complex PCI in our study is acceptably low. PCI on ULM carries a higher risk of complications.

Comparison of clinical outcomes following percutaneous coronary intervention versus optimal medical therapy based on gray-zone fractional flow reserve in stable angina patients with intermediate coronary artery stenosis (COMFORTABLE prospective study): Study protocol for a multicenter randomized controlled trial

Background

Even in the current drug-eluting stent era, revascularization for coronary stenosis with fractional flow reserve (FFR) between 0.75 and 0.80, the so-called “gray zone,” is a matter of debate. Previous studies have reported conflicting results regarding outcomes of revascularization versus deferral for coronary stenosis when FFR values are in the gray zone, but these studies have had differing designs and populations. We therefore will investigate whether medical therapy plus percutaneous coronary intervention (PCI) is superior to medical therapy alone in reducing major cardiovascular events in patients presenting with coronary stenosis with gray zone FFR values.

Methods/design

This is a prospective, multicenter, open-label, parallel group, randomized, controlled, superiority study. A total of 410 eligible participants will be recruited and randomized to either the medical therapy plus PCI group or the medical therapy alone group. The primary endpoint is 1-year major adverse cardiac events (MACEs), defined as a combined endpoint of all-cause death, nonfatal myocardial infarction (MI), or unplanned target vessel revascularization (TVR). Secondary endpoints include MACE at 2 and 5 years. Moreover, each individual component of the primary endpoint, cardiovascular death, target vessel-related and non-target vessel-related MI, all MI, clinically driven TVR or non-TVR, all revascularization, stent thrombosis, and angina symptom status will be evaluated at 1, 2, and 5 years.

Discussion

This is the first prospective, multicenter, randomized, controlled study to investigate the superiority of medical therapy plus PCI over medical therapy by itself in reducing major cardiovascular events in patients presenting with coronary stenosis with “gray zone” FFR values. The results will help interventional cardiologists in making revascularization decisions regarding coronary stenosis with gray zone FFR values.

Trial registration

University Hospital Medical Information Network Clinical Trials Registry, UMIN000031526. Registered on 1 March 2018.

Electronic supplementary material

The online version of this article (10.1186/s13063-019-3182-1) contains supplementary material, which is available to authorized users.

Real-world clinical utility and impact on clinical decision-making of coronary computed tomography angiography-derived fractional flow reserve: lessons from the ADVANCE Registry

AIMS

Non-invasive assessment of stable chest pain patients is a critical determinant of resource utilization and clinical outcomes. Increasingly coronary computed tomography angiography (CCTA) with selective CCTA-derived fractional flow reserve (FFRCT) is being used. The ADVANCE Registry, is a large prospective examination of using a CCTA and FFRCT diagnostic pathway in real-world settings, with the aim of determining the impact of this pathway on decision-making, downstream invasive coronary angiography (ICA), revascularization, and major adverse cardiovascular events (MACE).

METHODS AND RESULTS

A total of 5083 patients with symptoms concerning for coronary artery disease (CAD) and atherosclerosis on CCTA were enrolled at 38 international sites from 15 July 2015 to 20 October 2017. Demographics, symptom status, CCTA and FFRCT findings, treatment plans, and 90 days outcomes were recorded. The primary endpoint of reclassification between core lab CCTA alone and CCTA plus FFRCT-based management plans occurred in 66.9% [confidence interval (CI): 64.8-67.6] of patients. Non-obstructive coronary disease was significantly lower in ICA patients with FFRCT ≤0.80 (14.4%) compared to patients with FFRCT >0.80 (43.8%, odds ratio 0.19, CI: 0.15-0.25, P < 0.001). In total, 72.3% of subjects undergoing ICA with FFRCT ≤0.80 were revascularized. No death/myocardial infarction (MI) occurred within 90 days in patients with FFRCT >0.80 (n = 1529), whereas 19 (0.6%) MACE [hazard ratio (HR) 19.75, CI: 1.19-326, P = 0.0008] and 14 (0.3%) death/MI (HR 14.68, CI 0.88-246, P = 0.039) occurred in subjects with an FFRCT ≤0.80.

CONCLUSIONS

In a large international multicentre population, FFRCT modified treatment recommendation in two-thirds of subjects as compared to CCTA alone, was associated with less negative ICA, predicted revascularization, and identified subjects at low risk of adverse events through 90 days.

Retrospective Comparison of Long-Term Clinical Outcomes Between Percutaneous Coronary Intervention and Medical Therapy in Stable Coronary Artery Disease With Gray Zone Fractional Flow Reserve - COMFORTABLE Retrospective Study

BACKGROUND

A fractional flow reserve (FFR) between 0.75 and 0.80 constitutes a "gray zone" for clinical decision-making in coronary artery disease. We compared long-term outcomes of percutaneous coronary intervention (PCI) using drug-eluting stents vs. medical therapy for coronary stenosis with gray zone FFR. Methods and Results: We retrospectively investigated the clinical outcomes of 263 patients with gray zone FFR: 78 patients in the PCI group and 185 patients in the medical therapy group. During a median follow-up of 3.7 years, the frequency of target vessel failure (TVF, defined as a composite of cardiac death, myocardial infarction [MI], or ischemia-driven target vessel revascularization [TVR]) was significantly lower in the PCI group compared with the medical therapy group (6% vs. 19%, hazard ratio [HR]:0.33, 95% confidence interval [CI]: 0.13-0.84, P=0.008). The frequency of a composite of cardiac death or MI was not different between the 2 groups (1% vs. 2%, HR: 0.61, 95% CI: 0.07-5.49, P=0.645). The frequency of ischemia-driven TVR was significantly lower in the PCI group compared with the medical therapy group (5% vs. 18%, HR: 0.28, 95% CI: 0.10-0.79, P=0.005).

CONCLUSIONS

In patients with gray zone FFR, compared with medical therapy, PCI decreased the frequency of TVF, which was mainly driven by a reduction in the frequency of angina or myocardial ischemia without any difference in the frequency of cardiac death or MI.