Comparison of Fractional FLow Reserve And Intravascular ultrasound-guided Intervention Strategy for Clinical OUtcomes in Patients with InteRmediate Stenosis (FLAVOUR): Rationale and design of a randomized clinical trial

Discordance Between Angiographic Assessment and Fractional Flow Reserve or Intravascular Ultrasound in Intermediate Coronary Lesions: A Post-hoc Analysis of the FLAVOUR Trial

BACKGROUND AND OBJECTIVES

Angiographic assessment of coronary stenosis severity using quantitative coronary angiography (QCA) is often inconsistent with that based on fractional flow reserve (FFR) or intravascular ultrasound (IVUS). We investigated the incidence of discrepancies between QCA and FFR or IVUS, and the outcomes of FFR- and IVUS-guided strategies in discordant coronary lesions.

METHODS

This study was a post-hoc analysis of the FLAVOUR study. We used a QCA-derived diameter stenosis (DS) of 60% or greater, the highest tertile, to classify coronary lesions as concordant or discordant with FFR or IVUS criteria for percutaneous coronary intervention (PCI). The patient-oriented composite outcome (POCO) was defined as a composite of death, myocardial infarction, or revascularization at 24 months.

RESULTS

The discordance rate between QCA and FFR or IVUS was 30.2% (n=551). The QCA-FFR discordance rate was numerically lower than the QCA-IVUS discordance rate (28.2% vs. 32.4%, p=0.050). In 200 patients with ≥60% DS, PCI was deferred according to negative FFR (n=141) and negative IVUS (n=59) (15.3% vs. 6.5%, p<0.001). The POCO incidence was comparable between the FFR- and IVUS-guided deferral strategies (5.9% vs. 3.4%, p=0.479). Conversely, 351 patients with DS <60% underwent PCI according to positive FFR (n=118) and positive IVUS (n=233) (12.8% vs. 25.9%, p<0.001). FFR- and IVUS-guided PCI did not differ in the incidence of POCO (9.5% vs. 6.5%, p=0.294).

CONCLUSIONS

The proportion of QCA-FFR or IVUS discordance was approximately one third for intermediate coronary lesions. FFR- or IVUS-guided strategies for these lesions were comparable with respect to POCO at 24 months.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02673424.

Physiology- or Imaging-Guided Strategies for Intermediate Coronary Stenosis

Importance

Treatment strategies for intermediate coronary lesions guided by fractional flow reserve (FFR) and intravascular ultrasonography (IVUS) have shown comparable outcomes. Identifying low-risk deferred vessels to ensure the safe deferral of percutaneous coronary intervention (PCI) and high-risk revascularized vessels that necessitate thorough follow-up can help determine optimal treatment strategies.

Objectives

To investigate outcomes according to treatment types and FFR and IVUS parameters after FFR- or IVUS-guided treatment.

Design, Setting, and Participants

This cohort study included patients with intermediate coronary stenosis from the Fractional Flow Reserve and Intravascular Ultrasound-Guided Intervention Strategy for Clinical Outcomes in Patients With Intermediate Stenosis (FLAVOUR) trial, an investigator-initiated, prospective, open-label, multicenter randomized clinical trial that assigned patients into an IVUS-guided strategy (which recommended PCI for minimum lumen area [MLA] ≤3 mm2 or 3 mm2 to 4 mm2 with plaque burden [PB] ≥70%) or an FFR-guided strategy (which recommended PCI for FFR ≤0.80). Data were analyzed from November to December 2022.

Exposures

FFR or IVUS parameters within the deferred and revascularized vessels.

Main Outcomes and Measures

The primary outcome was target vessel failure (TVF), a composite of cardiac death, target vessel myocardial infarction, and revascularization at 2 years.

Results

A total of 1619 patients (mean [SD] age, 65.1 [9.6] years; 1137 [70.2%] male) with 1753 vessels were included in analysis. In 950 vessels for which revascularization was deferred, incidence of TVF was comparable between IVUS and FFR groups (3.8% vs 4.1%; P = .72). Vessels with FFR greater than 0.92 in the FFR group and MLA greater than 4.5 mm2 or PB of 58% or less in the IVUS group were identified as low-risk deferred vessels, with a decreased risk of TVF (hazard ratio [HR], 0.25 [95% CI, 0.09-0.71]; P = .009). In 803 revascularized vessels, the incidence of TVF was comparable between IVUS and FFR groups (3.6% vs 3.7%; P = .95), which was similar in the revascularized vessels undergoing PCI optimization (4.2% vs 2.5%; P = .31). Vessels with post-PCI FFR of 0.80 or less in the FFR group or minimum stent area of 6.0 mm2 or less or with PB at stent edge greater than 58% in the IVUS group had an increased risk for TVF (HR, 7.20 [95% CI, 3.20-16.21]; P < .001).

Conclusions and Relevance

In this cohort study of patients with intermediate coronary stenosis, FFR- and IVUS-guided strategies showed comparable outcomes in both deferred and revascularized vessels. Binary FFR and IVUS parameters could further define low-risk deferred vessels and high-risk revascularized vessels.

Rationale and design of a comparison of angiography-derived fractional flow reserve-guided and intravascular ultrasound-guided intervention strategy for clinical outcomes in patients with coronary artery disease: a randomised controlled trial (FLAVOUR II)

INTRODUCTION

Percutaneous coronary intervention (PCI) guided by coronary angiography-derived fractional flow reserve (FFR) or intravascular ultrasound (IVUS) has shown improved clinical outcomes compared with angiography-only-guided PCI. In patients with intermediate stenoses, FFR resulted in fewer coronary interventions and was non-inferior to IVUS with respect to clinical outcomes. However, whether this finding can be applied to angiography-derived FFR in significant coronary artery disease (CAD) remains unclear.

METHOD AND ANALYSIS

The comparison of angiography-derived FFR-guided and IVUS-guided intervention strategies for clinical outcomes in patients with coronary artery disease (FLAVOUR II) trial is a multicentre, prospective, randomised controlled trial. A total of 1872 patients with angiographically significant CAD (stenoses of at least 50% as estimated visually through angiography) in a major epicardial coronary artery will be randomised 1:1 to receive either angiography-derived FFR-guided or IVUS-guided PCI. Patients will be treated with second-generation drug-eluting stent according to the predefined criteria for revascularisation: angiography-derived FFR≤0.8 and minimal lumen area (MLA)≤3 mm2 or 3 mm270%. The primary endpoint is a composite of all-cause death, myocardial infarction and revascularisation at 12 months after randomisation. We will test the non-inferiority of the angiography-derived FFR-guided strategy compared with the IVUS-guided decision for PCI and the stent optimisation strategy.The FLAVOUR II trial will provide new insights into optimal evaluation and treatment strategies for patients with CAD.

ETHICS AND DISSEMINATION

FLAVOUR II was approved by the institutional review board at each participating site (The Second Affiliated Hospital of Zhejiang University School of Medicine Approval No: 2020LSYD410) and will be conducted in line with the Declaration of Helsinki. Informed consent would be obtained from each patient before their participation. The study results will be submitted to a scientific journal.

TRIAL REGISTRATION NUMBER

NCT04397211.

Sex Differences in Fractional Flow Reserve- or Intravascular Ultrasound-Guided Percutaneous Coronary Intervention

BACKGROUND

A recent randomized trial reported fractional flow reserve (FFR)-guided percutaneous coronary intervention (PCI) strategy was noninferior to the intracoronary ultrasound (IVUS)-guided PCI strategy with respect to clinical outcomes with fewer revascularizations.

OBJECTIVES

This study sought to investigate the sex differences in treatment and clinical outcomes according to physiology- or imaging-guided PCI strategies.

METHODS

In this secondary analysis of the FLAVOUR (Fractional Flow Reserve or Intravascular Ultrasonography to Guide PCI) trial, the impact of sex on procedural characteristics, PCI rate, and outcomes according to different strategies and treatment types (PCI vs deferral of PCI) was analyzed. The primary outcome was target vessel failure (TVF) at 24 months, defined as a composite of cardiac death, target vessel myocardial infarction, and target vessel revascularization.

RESULTS

Of 1,619 patients, 30% were women. Compared with men, women had a smaller minimal lumen area, smaller plaque burden, and higher FFR. They had a lower PCI rate (40.8% vs 47.9%; P = 0.008), which was mainly contributed by FFR guidance. Overall, women showed a lower TVF rate (2.4% vs 4.5%). According to the treatment type, the cumulative incidence of TVF was lower in women than in men among those with the deferral of PCI (1.7% vs 5.2%). However, this trend was not observed in patients who underwent PCI. In both women and men, there were no differences in clinical outcomes between the FFR- and IVUS-guided strategies.

CONCLUSIONS

In cases of intermediate stenosis, despite receiving fewer interventions, women had more favorable outcomes than men. The use of FFR led to a lower PCI rate but had a similar prognostic value compared with IVUS in both women and men.

Fractional Flow Reserve or Intravascular Ultrasonography to Guide PCI

BACKGROUND

In patients with coronary artery disease who are being evaluated for percutaneous coronary intervention (PCI), procedures can be guided by fractional flow reserve (FFR) or intravascular ultrasonography (IVUS) for decision making regarding revascularization and stent implantation. However, the differences in clinical outcomes when only one method is used for both purposes are unclear.

METHODS

We randomly assigned 1682 patients who were being evaluated for PCI for the treatment of intermediate stenosis (40 to 70% occlusion by visual estimation on coronary angiography) in a 1:1 ratio to undergo either an FFR-guided or IVUS-guided procedure. FFR or IVUS was to be used to determine whether to perform PCI and to assess PCI success. In the FFR group, PCI was to be performed if the FFR was 0.80 or less. In the IVUS group, the criteria for PCI were a minimal lumen area measuring either 3 mm² or less or measuring 3 to 4 mm² with a plaque burden of more than 70%. The primary outcome was a composite of death, myocardial infarction, or revascularization at 24 months after randomization. We tested the noninferiority of the FFR group as compared with the IVUS group (noninferiority margin, 2.5 percentage points).

RESULTS

The frequency of PCI was 44.4% among patients in the FFR group and 65.3% among those in the IVUS group. At 24 months, a primary-outcome event had occurred in 8.1% of the patients in the FFR group and in 8.5% of those in the IVUS group (absolute difference, -0.4 percentage points; upper boundary of the one-sided 97.5% confidence interval, 2.2 percentage points; P = 0.01 for noninferiority). Patient-reported outcomes as reported on the Seattle Angina Questionnaire were similar in the two groups.

CONCLUSIONS

In patients with intermediate stenosis who were being evaluated for PCI, FFR guidance was noninferior to IVUS guidance with respect to the composite primary outcome of death, myocardial infarction, or revascularization at 24 months. (Funded by Boston Scientific; FLAVOUR ClinicalTrials.gov number, NCT02673424.).

Interactions Between Morphological Plaque Characteristics and Coronary Physiology: From Pathophysiological Basis to Clinical Implications

High-risk coronary plaque refers to a distinct set of plaque characteristics prone to future coronary events. Coronary physiology represents a group of indexes reflective of the local physiological environment and hemodynamic changes in the macrovascular and microvascular system. Although a large body of evidence has supported the clinical relevance of these 2 factors, currently, identifying plaque morphology cannot reliably capture the lesion subset that causes hard events. Also, the guideline-directed approach based on physiological indexes cannot fully predict and prevent clinical events. In parallel, there is accumulating evidence that these 2 aspects of coronary artery disease influence each other with significant clinical implications, despite traditionally being considered to have separate effects on significances, treatments, and outcomes. In this state-of-the-art review, we explore the clinical evidence of pathophysiological interplay of physiological indexes related to local hemodynamics, epicardial stenosis, and microvascular dysfunction with plaque morphological characteristics that provide a better understanding of the nature of coronary events. Furthermore, we examine the emerging data on the complementary role between plaque morphology and coronary physiology in prognostication and how to apply this concept to overcome the limitations of individual assessment alone. Finally, we propose the potential benefit of integrative assessment of coronary anatomy, plaque quantity and quality, and physiological aspects of a target lesion and vessels for personalized risk profiling and optimized treatment strategy.

Diagnostic Performance of Fractional Flow Reserve From CT Coronary Angiography With Analytical Method

The aim of this study was to evaluate a new analytical method for calculating non-invasive fractional flow reserve (FFR_AM) to diagnose ischemic coronary lesions. Patients with suspected or known coronary artery disease (CAD) who underwent computed tomography coronary angiography (CTCA) and invasive coronary angiography (ICA) with FFR measurements from two sites were prospectively recruited. Obstructive CAD was defined as diameter stenosis (DS) ≥50% on CTCA or ICA. FFR_AM was derived from CTCA images and anatomical features using analytical method and was compared with computational fluid dynamics (CFD)-based FFR (FFR_B) and invasive ICA-based FFR. FFR_AM, FFR_B, and invasive FFR ≤ 0.80 defined ischemia. A total of 108 participants (mean age 60, range: 30–83 years, 75% men) with 169 stenosed coronary arteries were analyzed. The per-vessel accuracy, sensitivity, specificity, and positive predictive and negative predictive values were, respectively, 81, 75, 86, 81, and 82% for FFR_AM and 87, 88, 86, 83, and 90% for FFR_B. The area under the receiver operating characteristics curve for FFR_AM (0.89 and 0.87) and FFR_B (0.90 and 0.86) were higher than both CTCA- and ICA-derived DS (all p < 0.0001) on per-vessel and per-patient bases for discriminating ischemic lesions. The computational time for FFR_AM was much shorter than FFR_B (2.2 ± 0.9 min vs. 48 ± 36 min, excluding image acquisition and segmentation). FFR_AM calculated from a novel and expeditious non-CFD approach possesses a comparable diagnostic performance to CFD-derived FFR_B, with a significantly shorter computational time.

Impact of Arterial Remodeling of Intermediate Coronary Lesions on Long-Term Clinical Outcomes in Patients with Stable Coronary Artery Disease: An Intravascular Ultrasound Study

Background

Treatment of coronary intermediate lesions remains a controversy, and the role of arterial remodeling patterns determined by intravascular ultrasound in intermediate lesion is still not well known. The aim of this study was to investigate the impact of arterial remodeling of intermediate coronary lesions on long-term clinical outcomes.

Methods

Arterial remodeling patterns were assessed in 212 deferred intermediate lesions from 162 patients after IVUS examination. Negative, intermediate, and positive remodeling was defined as a remodeling index of <0.88, 0.88∼1.0, and >1.0, respectively. The primary endpoint was the composite vessel-oriented clinical events, defined as the composition of target vessel-related cardiac death, target vessel-related myocardial infarction, and target vessel revascularization. Quantitative flow ratio was assessed for evaluating the functional significance of intermediate lesions.

Results

72 intermediate remodeling lesions were present in 66 patients, whereas 77 negative remodeling lesions were present in 71 patients, and 63 positive remodeling lesions were present in 55 patients. Negative remodeling lesions had the smallest minimum lumen area (4.16 ± 1.03 mm² vs. 5.05 ± 1.39 mm² vs. 4.85 ± 1.76 mm²; P < 0.01), smallest plaque burden (63.45 ± 6.13% vs. 66.12 ± 6.82% vs. 71.17 ± 6.45%; P < 0.01), and highest area stenosis rate (59.32% ± 10.15% vs. 54.61% ± 9.09% vs. 51.67% ± 12.96%; P < 0.01). No significant difference was found in terms of quantitative flow ratio among three groups. At 5 years follow-up, negative remodeling lesions had a higher rate of composite vessel-oriented clinical event (14.3%), compared to intermediate (1.4%, P=0.004) or positive remodeling lesions (4.8%, P=0.06). After adjusting for multiple covariates, negative remodeling remained an independent determinant for vessel-oriented clinical event (HR: 4.849, 95% CI 1.542-15.251, P=0.007).

Conclusion

IVUS-derived negative remodeling is associated with adverse long-term clinical outcome in stable patients with intermediate coronary artery stenosis.

Determining the Significance of Coronary Plaque Lesions: Physiological Stenosis Severity and Plaque Characteristics

The evaluation of coronary lesions has evolved in recent years. Physiologic-guided revascularization (particularly with pressure-derived fractional flow reserve (FFR)) has led to superior outcomes compared to traditional angiographic assessment. A greater importance, therefore, has been placed on the functional significance of an epicardial lesion. Despite the improvements in the limitations of angiography, insights into the relationship between hemodynamic significance and plaque morphology at the lesion level has shown that determining the implications of epicardial lesions is rather complex. Investigators have sought greater understanding by correlating ischemia quantified by FFR with plaque characteristics determined on invasive and non-invasive modalities. We review the background of the use of these diagnostic tools in coronary artery disease and discuss the implications of analyzing physiological stenosis severity and plaque characteristics concurrently.

Heart failure etiologies and clinical factors precipitating for worsening heart failure: Findings from BIOSTAT-CHF

BACKGROUND

Knowledge on the association between heart failure (HF) etiologies, precipitant causes and clinical outcomes may help in ascertaining patient's risk and in selecting tailored therapeutic strategies.

METHODS

The prognostic value of both HF etiologies and precipitants for worsening HF were analyzed using the index cohort of BIOSTAT-CHF. The studied HF etiologies were: a) ischemic HF; b) dilated cardiomyopathy; c) hypertensive HF; d) valvular HF; and e) other/unknown. The precipitating factors for worsening HF were: a) atrial fibrillation; b) non-adherence; c) renal failure; d) acute coronary syndrome; e) hypertension; and f) Infection. The primary outcome was the composite of all-cause death or HF hospitalization.

RESULTS

Among 2465 patients included in the study, 45% (N = =1102) had ischemic HF, 23% (N = =563) dilated cardiomyopathy, 15% (N = =379) other/unknown, 10% (N = =237) hypertensive and 7% (N = =184) valvular HF. Patients with ischemic HF had the worst prognosis, whereas patients with dilated cardiomyopathy had the best prognosis. From the precipitating factors for worsening HF, renal failure was the one independently associated with worse prognosis (adjusted HR (95%CI) = =1.48 (1.04-2.09), p < 0.001). We found no interaction between HF etiologies and precipitating factors for worsening HF with regard to the study outcomes (p interaction > 0.10 for all). Treatment up-titration benefited patients regardless of their underlying etiology or precipitating cause (p interaction > 0.10 for all).

CONCLUSIONS

In BIOSTAT-CHF, patients with HF of an ischemic etiology, and those with worsening HF precipitated by renal failure (irrespective of the underlying HF etiology), had the highest rates of death and HF hospitalization, but still benefited equally from treatment up-titration.