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

New Electrocardiographic Score for Predicting the Site of Coronary Artery Occlusion in Inferior Wall Acute Myocardial Infarction

Background

An electrocardiogram (ECG) was used to determine the type of acute myocardial infarction (MI) and locate the culprit vessel. Inferior wall myocardial infarction (IWMI) patients with the right coronary artery (RCA) as the culprit vessel may have a worse clinical prognosis than the left circumflex artery (LCx). We aimed to develop a new, simple, accurate scoring system to localize the RCA.

Methods

From January 2018 to January 2020, patients were admitted to the Department of Cardiology of TEDA International Cardiovascular Hospital and the Second Hospital of Tianjin Medical University due to IWMI and coronary angiography confirmed that the infarct-related vessel was a single RCA or LCx. ECG of patients before percutaneous coronary intervention (PCI) was collected to quantitatively analyze the characteristics of ST-segment deviation in non-inferior wall leads (N-IWL) and establish the RCA score in N-IWL.

Results

149 patients were enrolled, including 83 in the RCA group and 66 in the LCx group. Finally, ST-segment depression (ST↓) lead I, aVR, V1, and V6, and ST↓≥ 1mm in lead V4 were found to be associated with the location of the RCA. The sensitivity, specificity, and area under the curve (AUC) of the N-IWL RCA scoring system were 77.1%, 72.7%, and 0.83, respectively. The diagnostic ability of the scoring system was better than that of other algorithms and scoring systems.

Conclusion

ECG helps identify the RCA in patients with IWMI before PCI. The N-IWL RCA score may help identify the culprit vessel as the RCA in patients with IWMI.

Plaque Ruptures Are Related to High Plaque Stress and Strain Conditions: Direct Verification by Using In Vivo OCT Rupture Data and FSI Models

BACKGROUND

While it has been hypothesized that high plaque stress and strain may be related to plaque rupture, its direct verification using in vivo coronary plaque rupture data and full 3-dimensional fluid-structure interaction models is lacking in the current literature due to difficulty in obtaining in vivo plaque rupture imaging data from patients with acute coronary syndrome. This case-control study aims to use high-resolution optical coherence tomography-verified in vivo plaque rupture data and 3-dimensional fluid-structure interaction models to seek direct evidence for the high plaque stress/strain hypothesis.

METHODS

In vivo coronary plaque optical coherence tomography data (5 ruptured plaques, 5 no-rupture plaques) were acquired from patients using a protocol approved by the local institutional review board with informed consent obtained. The ruptured caps were reconstructed to their prerupture morphology using neighboring plaque cap and vessel geometries. Optical coherence tomography-based 3-dimensional fluid-structure interaction models were constructed to obtain plaque stress, strain, and flow shear stress data for comparative analysis. The rank-sum test in the nonparametric test was used for statistical analysis.

RESULTS

Our results showed that the average maximum cap stress and strain values of ruptured plaques were 142% (457.70 versus 189.22 kPa; P=0.0278) and 48% (0.2267 versus 0.1527 kPa; P=0.0476) higher than that for no-rupture plaques, respectively. The mean values of maximum flow shear stresses for ruptured and no-rupture plaques were 145.02 dyn/cm2 and 81.92 dyn/cm2 (P=0.1111), respectively. However, the flow shear stress difference was not statistically significant.

CONCLUSIONS

This preliminary case-control study showed that the ruptured plaque group had higher mean maximum stress and strain values. Due to our small study size, larger scale studies are needed to further validate our findings.

Effects of adaptive or fixed thresholds and different platforms on the assessment of plaque characteristics using coronary computed tomography angiography

BACKGROUND

Coronary computed tomography angiography (CCTA) is used to evaluate components of atherosclerosis. Either adaptive or diverse, fixed Hounsfield Units (HU) are used to define components such as low attenuation (LAP), mixed (MP) and calcified plaque (CP). Comparisons of different platforms and different thresholding approaches have not been extensively evaluated. We compare two fixed threshold options to an adaptive threshold option within a specific platform and to fixed threshold options measured with another platform.

METHODS

Coronary segments (n ​= ​24) of good image quality, with well-defined boundaries and representing a broad range of atheroma were analyzed for LAP, MP and CP. Thresholds for LAP vs MP and MP vs CP were either Fixed30/350, Fixed75/350 or based on an automatically determined Adaptive option. Pearson correlation and Bland-Altman analyses were undertaken.

RESULTS

Within a single platform, measures were highly correlated irrespective of use of Adaptive or Fixed30/350 and Fixed75/350 thresholds (R ​≥ ​0.819, p ​< ​0.000001). The correlation slope for measures of LAP progressively diminished comparing the Adaptive versus Fixed30/350 and the Fixed75/350 versus the Fixed30/350 approaches but bias was small. Between-platform comparisons yielded less optimal results, particularly with respect to measures of LAP and with one platform yielding both very small LAP volumes and very small ranges of volumes.

CONCLUSION

Measures of plaque components are highly correlated irrespective of use of Adaptive or Fixed threshold approaches within a given platform. But measures are more affected by the specific proprietary algorithms employed than by specific thresholding options, especially for LAP.

Prognostic value of combined fractional flow reserve and pressure-bounded coronary flow reserve: outcomes in FFR and Pb-CFR assessment

BACKGROUND

Coronary flow reserve (CFR) has an emerging role to predict outcome in patients with and without flow-limiting stenoses. However, the role of its surrogate pressure bounded-CFR (Pb-CFR) is controversial. We investigated the usefulness of combined use of fractional flow reserve (FFR) and Pb-CFR to predict outcomes.

METHODS

This is a sub-study of the PROPHET-FFR Trial, including patients with chronic coronary syndrome and functionally tested coronary lesions. Patients were divided into four groups based on positive or negative FFR (cut-off 0.80) and preserved (lower boundary ≥2) or reduced (upper boundary <2) Pb-CFR: Group1 FFR≤0.80/ Pb-CFR <2; Group 2 FFR≤0.80/Pb-CFR≥2; Group 3 FFR >0.80/Pb-CFR<2; Group 4 FFR>0.80/Pb-CFR≥2. Lesions with positive FFR were treated with PCI. Primary endpoint was the rate of major adverse cardiac events (MACEs), defined as a composite of death from any cause, myocardial infarction, target vessel revascularization, unplanned cardiac hospitalization at 36-months.

RESULTS

A total of 609 patients and 816 lesions were available for the analysis. At Kaplan-Meier analysis MACEs rate was significantly different between groups (36.7% Group 1, 27.4% Group 2, 19.2% Group 3, 22.6% Group 4, P=0.019) and more prevalent in groups with FFR≤0.80 irrespective of Pb-CFR. In case of discrepancy, no difference in MACEs were observed between groups stratified by Pb-CFR. FFR≤0.80 was associated with an increased MACEs rate (30.2% vs. 21.5%, P<0.01) while Pb-CFR<2 was not (24.5% vs. 24.2% Pb-CFR≥2 P=0.67).

CONCLUSIONS

FFR confirms its ability to predict outcomes in patients with intermediate coronary stenoses. Pb-CFR does not add any relevant prognostic information.

Prognostic Implications of Quantitative Flow Ratio and Plaque Characteristics in Intravascular Ultrasound-Guided Treatment Strategy

BACKGROUND

Quantitative flow ratio (QFR) is a method for evaluating fractional flow reserve without the use of an invasive coronary pressure wire or pharmacological hyperemic agent.

OBJECTIVES

The aim of this study was to investigate the prognostic implications of QFR and plaque characteristics in patients who underwent intravascular ultrasound (IVUS)-guided treatment for intermediate lesions.

METHODS

Among the IVUS-guided strategy group in the FLAVOUR (Fractional Flow Reserve and Intravascular Ultrasound for Clinical Outcomes in Patients with Intermediate Stenosis) trial, vessels suitable for QFR analysis were included in this study. High-risk features were defined as low QFR (≤0.90), quantitative high-risk plaque characteristics (qn-HRPCs) (minimal lumen area ≤3.5 mm2, or plaque burden ≥70%), and qualitative high-risk plaque characteristics (ql-HRPCs) (attenuated plaque, positive remodeling, or plaque rupture) assessed using IVUS. The primary clinical endpoint was target vessel failure (TVF), defined as a composite of cardiac death, target vessel myocardial infarction, and target vessel revascularization.

RESULTS

A total of 415 (46.1%) vessels could be analyzable for QFR. The numbers of qn-HRPCs and ql-HRPCs increased with decreasing QFR. Among deferred vessels, those with 3 high-risk features exhibits a significantly higher risk of TVF compared with those with ≤2 high-risk features (12.0% vs 2.7%; HR: 4.54; 95% CI: 1.02-20.29).

CONCLUSIONS

Among the IVUS-guided deferred group, vessels with qn-HRPC and ql-HRPC with low QFR (≤0.90) exhibited a significantly higher risk for TVF compared with those with ≤2 features. Integrative assessment of angiography-derived fractional flow reserve and anatomical and morphological plaque characteristics is recommended to improve clinical outcomes in patients undergoing IVUS-guided deferred treatment.

Relationship of Coronary Angiography-Derived Radial Wall Strain With Functional Significance, Plaque Morphology, and Clinical Outcomes

BACKGROUND

Coronary angiography-derived radial wall strain (RWS) is a newly developed index that can be readily accessed and describes the biomechanical features of a lesion.

OBJECTIVES

The authors sought to investigate the association of RWS with fractional flow reserve (FFR) and high-risk plaque (HRP), and their relative prognostic implications.

METHODS

We included 484 vessels (351 patients) deferred after FFR measurement with available RWS data and coronary computed tomography angiography. On coronary computed tomography angiography, HRP was defined as a lesion with both minimum lumen area <4 mm2 and plaque burden ≥70%. The primary outcome was target vessel failure (TVF), a composite of target vessel revascularization, target vessel myocardial infarction, or cardiac death.

RESULTS

The mean FFR and RWSmax were 0.89 ± 0.07 and 11.2% ± 2.5%, respectively, whereas 27.7% of lesions had HRP, 15.1% had FFR ≤0.80. An increase in RWSmax was associated with a higher risk of FFR ≤0.80 and HRP, which was consistent after adjustment for clinical or angiographic characteristics (all P < 0.05). An increment of RWSmax was related to a higher risk of TVF (HR: 1.23 [95% CI: 1.03-1.47]; P = 0.022) with an optimal cutoff of 14.25%. RWSmax >14% was a predictor of TVF after adjustment for FFR or HRP components (all P < 0.05) and showed a direct prognostic effect on TVF, not mediated by FFR ≤0.80 or HRP in the mediation analysis. When high RWSmax was added to FFR ≤0.80 or HRP, there were increasing outcome trends (all P for trend <0.001).

CONCLUSIONS

RWS was associated with coronary physiology and plaque morphology but showed independent prognostic significance.

Fractional flow reserve versus intravascular imaging to guide decision-making for percutaneous coronary intervention in intermediate lesions: A meta-analysis

BACKGROUND

Both fractional flow reserve (FFR) and intravascular imaging (IVI) have been used to guide the decision-making for percutaneous coronary intervention (PCI) in intermediate coronary stenosis. Nevertheless, studies that directly compared the prognostic significance of these two strategies are scarce.

AIMS

The aim of this meta-analyses was to evaluate the impact of FFR versus IVI to guide the decision-making in PCI for intermediate stenosis on clinical outcomes.

METHODS

We systematically searched PubMed, Embase, Cochrane, and relevant database from inception date to September 2022 for observational studies and randomized clinical trials (RCTs) which compared FFR and IVI-based decision-making in PCI for intermediate stenosis. The primary outcome was a composite of major adverse cardiac event (MACE). Pooled risk ratios (RR) were calculated using random effects models and heterogeneity were evaluated with the I2 statistic.

RESULTS

We identified 5 studies (3 RCTs and 2 observational studies) with 3208 patients. The follow-up duration ranged from 12 to 24 months. Among five studies, four compared FFR with intravascular ultrasound while one compared FFR with optical coherence tomography. There was no statistically difference between FFR and IVI in the incidence of MACE (RR: 1.19; 95% confidence interval: 0.85-1.68; p = 0.31) and its individual components. These results were consistent regardless of various cut-off value of PCI across the studies. Compared with IVI, FFR was associated with a lower PCI rate (37.0% vs. 60.3%; p < 0.001).

CONCLUSIONS

The decision to perform PCI for intermediate stenosis guided by FFR or IVI showed a similar clinical outcome. The use of FFR significantly reduced the need for PCI.

Coronary Atherosclerosis Phenotypes in Focal and Diffuse Disease

BACKGROUND

The interplay between coronary hemodynamics and plaque characteristics remains poorly understood.

OBJECTIVES

The aim of this study was to compare atherosclerotic plaque phenotypes between focal and diffuse coronary artery disease (CAD) defined by coronary hemodynamics.

METHODS

This multicenter, prospective, single-arm study was conducted in 5 countries. Patients with functionally significant lesions based on an invasive fractional flow reserve ≤0.80 were included. Plaque analysis was performed by using coronary computed tomography angiography and optical coherence tomography. CAD patterns were assessed using motorized fractional flow reserve pullbacks and quantified by pullback pressure gradient (PPG). Focal and diffuse CAD was defined according to the median PPG value.

RESULTS

A total of 117 patients (120 vessels) were included. The median PPG was 0.66 (IQR: 0.54-0.75). According to coronary computed tomography angiography analysis, plaque burden was higher in patients with focal CAD (87% ± 8% focal vs 82% ± 10% diffuse; P = 0.003). Calcifications were significantly more prevalent in patients with diffuse CAD (Agatston score per vessel: 51 [IQR: 11-204] focal vs 158 [IQR: 52-341] diffuse; P = 0.024). According to optical coherence tomography analysis, patients with focal CAD had a significantly higher prevalence of circumferential lipid-rich plaque (37% focal vs 4% diffuse; P = 0.001) and thin-cap fibroatheroma (TCFA) (47% focal vs 10% diffuse; P = 0.002). Focal disease defined by PPG predicted the presence of TCFA with an area under the curve of 0.73 (95% CI: 0.58-0.87).

CONCLUSIONS

Atherosclerotic plaque phenotypes associate with intracoronary hemodynamics. Focal CAD had a higher plaque burden and was predominantly lipid-rich with a high prevalence of TCFA, whereas calcifications were more prevalent in diffuse CAD. (Precise Percutaneous Coronary Intervention Plan [P3]; NCT03782688).

Machine learning based ischemia-specific stenosis prediction: A Chinese multicenter coronary CT angiography study

OBJECTIVES

To evaluate the performance of coronary computed tomography angiography (CCTA) derived characteristics including CT derived fractional flow reserve (CT-FFR) with FFR as a reference standard in identifying the lesion-specific ischemia by machine learning (ML) algorithms.

METHODS

The retrospective analysis enrolled 596 vessels in 462 patients (mean age, 61 years ± 11 [SD]; 71.4 % men) with suspected coronary artery disease who underwent CCTA and invasive FFR. The data were divided into training cohort, internal validation cohort, external validation cohorts 1 and 2 according to participating centers. All CCTA-derived parameters, which contained 10 qualitative and 33 quantitative plaque parameters, were collected to establish ML model. The Boruta and unsupervised clustering algorithm were implemented to select important and non-redundant parameters. Finally, the eight features with the highest mean importance were included for further ML model establishment and decision tree building. Five models were built to predict lesion-specific ischemia: stenosis degree from CCTA, CT-FFR, ΔCT-FFR, ML model and nested model.

RESULTS

Low-attenuation plaque, bend and lesion length were the main predictors of ischemia-specific lesions. Of 5 models, the ML model showed favorable discrimination for ischemia-specific lesions in the training and three validation sets (area under the curve [95 % confidence interval], 0.93 [0.90-0.96], 0.86 [0.79-0.94], 0.88 [0.83-0.94], and 0.90 [0.84-0.96], respectively). The nested model which combined the ML model and CT-FFR showed better diagnostic efficacy (AUC [95 %CI], 0.96 [0.94-0.99], 0.92 [0.86-0.99], 0.92 [0.86-0.99] and 0.94 [0.91-0.98], respectively; all P < 0.05), and net reclassification improvement (NRI) and integrated discrimination improvement (IDI) were significantly higher than CT-FFR alone.

CONCLUSIONS

Comprehensive CCTA-derived multiparameter model could better predict the ischemia-specific lesions by ML algorithms compared to stenosis degree from CTA, CT-FFR and ΔCT-FFR. Decision tree can be used to predict myocardial ischemia effectively.

Melatonin ameliorates atherosclerosis by suppressing S100a9-mediated vascular inflammation

Atherosclerosis (AS)-associated cardiovascular diseases are predominant causes of morbidity and mortality worldwide. Melatonin, a circadian hormone with anti-inflammatory activity, may be a novel therapeutic intervention for AS. However, the exact mechanism is unclear. This research intended to investigate the mechanism of melatonin in treating AS. Melatonin (20 mg/kg/d) was intraperitoneally administered in a high-fat diet (HFD)-induced AS model using apolipoprotein E-deficient (ApoE-/-) mice for 12 weeks. Immunohistochemical and immunofluorescence analyses, data-independent acquisition (DIA)-based protein profiling, ingenuity pathway analysis (IPA), and western blotting were employed to investigate the therapeutic effects of melatonin in treating HFD-induced AS. An adeno-associated virus (AAV) vector was further used to confirm the antiatherosclerotic mechanism of melatonin. Melatonin treatment markedly attenuated atherosclerotic lesions, induced stable phenotypic sclerotic plaques, inhibited macrophage infiltration, and suppressed the production of proinflammatory cytokines in ApoE-/- mice with HFD-induced AS. Notably, DIA-based quantitative proteomics together with IPA identified S100a9 as a pivotal mediator in the protective effects of melatonin. Moreover, melatonin significantly suppressed HFD-induced S100a9 expression at both the mRNA and protein levels. The overexpression of S100a9 significantly activated the NF-κB signaling pathway and markedly abolished the antagonistic effect of melatonin on HFD-induced vascular inflammation during atherogenesis. Melatonin exerts a significant antiatherogenic effect by inhibiting S100a9/NF-κB signaling pathway-mediated vascular inflammation. Our findings reveal a novel antiatherosclerotic mechanism of melatonin and underlie its potential clinical use in modulating AS with good availability and affordability.

Coronary Physiology-Based Approaches for Plaque Vulnerability: Implications for Risk Prediction and Treatment Strategies

In the catheterization laboratory, the measurement of physiological indexes can help identify functionally significant lesions and has become one of the standard methods to guide treatment decision-making. Plaque vulnerability refers to a coronary plaque susceptible to rupture, enabling risk prediction before coronary events, and it can be detected by defining a certain type of plaque morphology on coronary imaging modalities. Although coronary physiology and plaque vulnerability have been considered different attributes of coronary artery disease, the underlying pathophysiological basis and clinical data indicate a strong correlation between coronary hemodynamic properties and vulnerable plaque. In prediction of coronary events, emerging data have suggested independent and additional implications of a physiology-based approach to a plaque-based approach. This review covers the fundamental interplay between coronary physiology and plaque morphology during disease progression with clinical data supporting this relationship and examines the clinical relevance of physiological indexes in prediction of clinical outcomes and therapeutic decision-making along with plaque vulnerability.

Intravascular imaging of angioplasty balloon under-expansion during pre-dilation predicts hyperelastic behavior of coronary artery lesions

Introduction: Stent-induced mechanical stimuli cause pathophysiological responses in the coronary artery post-treatment. These stimuli can be minimized through choice of stent, size, and deployment strategy. However, the lack of target lesion material characterization is a barrier to further personalizing treatment. A novel ex-vivo angioplasty-based intravascular imaging technique using optical coherence tomography (OCT) was developed to characterize local stiffness of the target lesion. Methods: After proper institutional oversight, atherosclerotic coronary arteries (n = 9) were dissected from human donor hearts for ex vivo material characterization <48 h post-mortem. Morphology was imaged at the diastolic blood pressure using common intravascular OCT protocols and at subsequent pressures using a specially fabricated perfusion balloon that accommodates the OCT imaging wire. Balloon under-expansion was quantified relative to the nominal balloon size at 8 ATM. Correlation to a constitutive hyperelastic model was empirically investigated (n = 13 plaques) using biaxial extension results fit to a mixed Neo-Hookean and Exponential constitutive model. Results and discussion: The average circumferential Cauchy stress was 66.5, 130.2, and 300.4 kPa for regions with <15, 15-30, and >30% balloon under-expansion at a 1.15 stretch ratio. Similarly, the average longitudinal Cauchy stress was 68.1, 172.6, and 412.7 kPa, respectively. Consequently, strong correlation coefficients >0.89 were observed between balloon under-expansion and stress-like constitutive parameters. These parameters allowed for visualization of stiffness and material heterogeneity for a range of atherosclerotic plaques. Balloon under-expansion is a strong predictor of target lesion stiffness. These findings are promising as stent deployment could now be further personalized via target lesion material characterization obtained pre-operatively.

Long-term prognostic implications of hemodynamic and plaque assessment using coronary CT angiography

BACKGROUND AND AIMS

Hemodynamic and plaque characteristics can be analyzed using coronary CT angiography (CTA). We aimed to explore long-term prognostic implications of hemodynamic and plaque characteristics using coronary CT angiography (CTA).

METHODS

Invasive fractional flow reserve (FFR) and CTA-derived FFR (FFR_CT) were undertaken for 136 lesions in 78 vessels and followed-up to 10 years until December 2020. FFR_CT, wall shear stress (WSS), change in FFR_CT across the lesion (ΔFFR_CT), total plaque volume (TPV), percent atheroma volume (PAV), and low-attenuation plaque volume (LAPV) for target lesions [L] and vessels [V] were obtained by independent core laboratories. Their collective influence was evaluated for the clinical endpoints of target vessel failure (TVF) and target lesion failure (TLF).

RESULTS

During a median follow-up of 10.1 years, PAV[V] (per 10% increase, HR 2.32 [95% CI 1.11-4.86], p = 0.025), and FFR_CT[V] (per 0.1 increase, HR 0.56 [95% CI 0.37-0.84], p = 0.006) were independent predictors of TVF for the per-vessel analysis, and WSS[L] (per 100 dyne/cm² increase, HR 1.43 [1.09-1.88], p = 0.010), LAPV[L] (per 10 mm³ increase, HR 3.81 [1.16-12.5], p = 0.028), and ΔFFR_CT[L] (per 0.1 increase, HR 1.39 [1.02-1.90], p = 0.040) were independent predictors of TLF for the per-lesion analysis after adjustment for clinical and lesion characteristics. The addition of both plaque and hemodynamic predictors improved the predictability for 10-year TVF and TLF of clinical and lesion characteristics (all p < 0.05).

CONCLUSIONS

Vessel- and lesion-level hemodynamic characteristics, and vessel-level plaque quantity, and lesion-level plaque compositional characteristics assessed by CTA offer independent and additive long-term prognostic value.

Machine Learning From Quantitative Coronary Computed Tomography Angiography Predicts Fractional Flow Reserve-Defined Ischemia and Impaired Myocardial Blood Flow

BACKGROUND

A pathophysiological interplay exists between plaque morphology and coronary physiology. Machine learning (ML) is increasingly being applied to coronary computed tomography angiography (CCTA) for cardiovascular risk stratification. We sought to assess the performance of a ML score integrating CCTA-based quantitative plaque features for predicting vessel-specific ischemia by invasive fractional flow reserve (FFR) and impaired myocardial blood flow (MBF) by positron emission tomography (PET).

METHODS

This post-hoc analysis of the PACIFIC trial (Prospective Comparison of Cardiac Positron Emission Tomography/Computed Tomography [CT]' Single Photon Emission Computed Tomography/CT Perfusion Imaging and CT Coronary Angiography with Invasive Coronary Angiography) included 208 patients with suspected coronary artery disease who prospectively underwent CCTA' [15O]H2O PET, and invasive FFR. Plaque quantification from CCTA was performed using semiautomated software. An ML algorithm trained on the prospective NXT trial (484 vessels) was used to develop a ML score for the prediction of ischemia (FFR≤0.80), which was then evaluated in 581 vessels from the PACIFIC trial. Thereafter, the ML score was applied for predicting impaired hyperemic MBF (≤2.30 mL/min per g) from corresponding PET scans. The performance of the ML score was compared with CCTA reads and noninvasive FFR derived from CCTA (FFRCT).

RESULTS

One hundred thirty-nine (23.9%) vessels had FFR-defined ischemia, and 195 (33.6%) vessels had impaired hyperemic MBF. For the prediction of FFR-defined ischemia, the ML score yielded an area under the receiver-operating characteristic curve of 0.92, which was significantly higher than that of visual stenosis grade (0.84; P<0.001) and comparable with that of FFRCT (0.93; P=0.34). Quantitative percent diameter stenosis and low-density noncalcified plaque volume had the greatest ML feature importance for predicting FFR-defined ischemia. When applied for impaired MBF prediction, the ML score exhibited an area under the receiver-operating characteristic curve of 0.80; significantly higher than visual stenosis grade (area under the receiver-operating characteristic curve 0.74; P=0.02) and comparable with FFRCT (area under the receiver-operating characteristic curve 0.77; P=0.16).

CONCLUSIONS

An externally validated ML score integrating CCTA-based quantitative plaque features accurately predicts FFR-defined ischemia and impaired MBF by PET, performing superiorly to standard CCTA stenosis evaluation and comparably to FFRCT.

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.).

Relationship of Plaque Features at Coronary CT to Coronary Hemodynamics and Cardiovascular Events

Background Plaque assessments with coronary CT angiography (CCTA) and coronary flow indexes have prognostic implications. Purpose To investigate the association and additive prognostic value of plaque burden and characteristics at CCTA with coronary pressure and flow. Materials and Methods Data of patients with coronary artery disease who underwent CCTA within 90 days before physiologic assessments at tertiary cardiovascular centers between January 2011 and December 2018 were retrospectively analyzed, which included fractional flow reserve (FFR), resting distal coronary artery pressure (Pd)-to-aortic pressure (Pa) ratio (hereafter, Pd/Pa), coronary flow reserve (CFR), hyperemic flow (1/hyperemic mean transit time [Tmn]), resting flow (1/resting Tmn), and index of microcirculatory resistance (IMR). Four high-risk plaque (HRP) attributes at CCTA defined high disease burden (plaque burden, ≥70%; minimum lumen area, <4 mm²) and adverse plaque (low-attenuation plaque, positive remodeling). Their lesion-specific relationships with coronary hemodynamic parameters and major adverse cardiovascular events (MACE) were investigated using a generalized estimating equation and marginal Cox model. Results Among 406 lesions from 335 patients (mean age, 67 years ± 10 [SD]; 259 men), high disease burden is predicted by FFR (odds ratio [OR], 0.55; P < .001), resting Pd/Pa (OR, 0.47; P < .001), CFR (OR, 0.85; P = .004), and hyperemic flow (OR, 0.91; P = .03), and adverse plaque by FFR (OR, 0.67; P < .001), resting Pd/Pa (OR, 0.69; P = .001), hyperemic flow (OR, 0.76; P = .006), resting flow (OR, 0.54; P = .001), and IMR (OR, 1.27; P = .008). High disease burden (hazard ratio [HR], 4.0; P = .004) and adverse plaque (HR, 2.7; P = .02) were associated with a higher risk of MACE (n = 27) over median 2.9-year follow-up. In six lesion subsets with normal flow or pressure, at least three HRP attributes predicted a higher MACE rate (HR range, 2.6-6.3). Conclusion High-risk plaque features and plaque burden at coronary CT angiography were associated with cardiovascular events independent of coronary hemodynamic parameters. Clinical trial registration no. NCT04037163 © RSNA, 2022 Online supplemental material is available for this article. See also the editorial by Leipsic and Tzimas in this issue.