Impact of Society Guidelines on Trends in Use of Newer P2Y12 Inhibitors for Patients With Acute Coronary Syndromes Undergoing Percutaneous Coronary Intervention

BACKGROUND

Over the past decade, major society guidelines have recommended the use of newer P2Y12 inhibitors over clopidogrel for those undergoing percutaneous coronary intervention for acute coronary syndrome. It is unclear what impact these recommendations had on clinical practice.

METHODS AND RESULTS

All percutaneous coronary intervention procedures (n=534 210) for acute coronary syndrome in England and Wales (April 1, 2010, to March 31, 2022) were retrospectively analyzed, stratified by choice of preprocedural P2Y12 inhibitor (clopidogrel, ticagrelor, and prasugrel). Multivariable logistic regression models were used to examine odds ratios of receipt of ticagrelor and prasugrel (versus clopidogrel) over time, and predictors of their receipt. Overall, there was a significant increase in receipt of newer P2Y12 inhibitors from 2010 to 2020 (2022 versus 2010: ticagrelor odds ratio, 8.12 [95% CI, 7.67-8.60]; prasugrel odds ratio, 6.14 [95% CI, 5.53-6.81]), more so in ST-segment-elevation myocardial infarction than non-ST-segment-elevation acute coronary syndrome indication. The most significant increase in odds of receipt of prasugrel was observed between 2020 and 2022 (P<0.001), following a decline/plateau in its use in earlier years (2011-2019). In contrast, the odds of receipt of ticagrelor significantly increased in earlier years (2012-2017, Ptrend<0.001), after which the trend was stable (Ptrend=0.093).

CONCLUSIONS

Over a 13-year-period, there has been a significant increase in use of newer P2Y12 inhibitors, although uptake of prasugrel use remained significantly lower than ticagrelor. Earlier society guidelines (pre-2017) were associated with the highest rates of ticagrelor use for non-ST-segment-elevation acute coronary syndrome and ST-segment-elevation myocardial infarction cases while the ISAR-REACT 5 (Prospective, Randomized Trial of Ticagrelor Versus Prasugrel in Patients With Acute Coronary Syndrome) trial and later society guidelines were associated with higher prasugrel use, mainly for ST-segment-elevation myocardial infarction indication.

A physics-based machine learning technique rapidly reconstructs the wall-shear stress and pressure fields in coronary arteries

With the global rise of cardiovascular disease including atherosclerosis, there is a high demand for accurate diagnostic tools that can be used during a short consultation. In view of pathology, abnormal blood flow patterns have been demonstrated to be strong predictors of atherosclerotic lesion incidence, location, progression, and rupture. Prediction of patient-specific blood flow patterns can hence enable fast clinical diagnosis. However, the current state of art for the technique is by employing 3D-imaging-based Computational Fluid Dynamics (CFD). The high computational cost renders these methods impractical. In this work, we present a novel method to expedite the reconstruction of 3D pressure and shear stress fields using a combination of a reduced-order CFD modelling technique together with non-linear regression tools from the Machine Learning (ML) paradigm. Specifically, we develop a proof-of-concept automated pipeline that uses randomised perturbations of an atherosclerotic pig coronary artery to produce a large dataset of unique mesh geometries with variable blood flow. A total of 1,407 geometries were generated from seven reference arteries and were used to simulate blood flow using the CFD solver Abaqus. This CFD dataset was then post-processed using the mesh-domain common-base Proper Orthogonal Decomposition (cPOD) method to obtain Eigen functions and principal coefficients, the latter of which is a product of the individual mesh flow solutions with the POD Eigenvectors. Being a data-reduction method, the POD enables the data to be represented using only the ten most significant modes, which captures cumulatively greater than 95% of variance of flow features due to mesh variations. Next, the node coordinate data of the meshes were embedded in a two-dimensional coordinate system using the t-distributed Stochastic Neighbor Embedding (t -SNE) algorithm. The reduced dataset for t -SNE coordinates and corresponding vector of POD coefficients were then used to train a Random Forest Regressor (RFR) model. The same methodology was applied to both the volumetric pressure solution and the wall shear stress. The predicted pattern of blood pressure, and shear stress in unseen arterial geometries were compared with the ground truth CFD solutions on "unseen" meshes. The new method was able to reliably reproduce the 3D coronary artery haemodynamics in less than 10 s.

Heterogeneous plaque-lumen geometry is associated with major adverse cardiovascular events

Aims

Prospective studies show that only a minority of plaques with higher risk features develop future major adverse cardiovascular events (MACE), indicating the need for more predictive markers. Biomechanical estimates such as plaque structural stress (PSS) improve risk prediction but require expert analysis. In contrast, complex and asymmetric coronary geometry is associated with both unstable presentation and high PSS, and can be estimated quickly from imaging. We examined whether plaque-lumen geometric heterogeneity evaluated from intravascular ultrasound affects MACE and incorporating geometric parameters enhances plaque risk stratification.

Methods and results

We examined plaque-lumen curvature, irregularity, lumen aspect ratio (LAR), roughness, PSS, and their heterogeneity indices (HIs) in 44 non-culprit lesions (NCLs) associated with MACE and 84 propensity-matched no-MACE-NCLs from the PROSPECT study. Plaque geometry HI were increased in MACE-NCLs vs. no-MACE-NCLs across whole plaque and peri-minimal luminal area (MLA) segments (HI curvature: adjusted P = 0.024; HI irregularity: adjusted P = 0.002; HI LAR: adjusted P = 0.002; HI roughness: adjusted P = 0.004). Peri-MLA HI roughness was an independent predictor of MACE (hazard ratio: 3.21, P < 0.001). Inclusion of HI roughness significantly improved the identification of MACE-NCLs in thin-cap fibroatheromas (TCFA, P < 0.001), or with MLA ≤ 4 mm2 (P < 0.001), or plaque burden (PB) ≥ 70% (P < 0.001), and further improved the ability of PSS to identify MACE-NCLs in TCFA (P = 0.008), or with MLA ≤ 4 mm2 (P = 0.047), and PB ≥ 70% (P = 0.003) lesions.

Conclusion

Plaque-lumen geometric heterogeneity is increased in MACE vs. no-MACE-NCLs, and inclusion of geometric heterogeneity improves the ability of imaging to predict MACE. Assessment of geometric parameters may provide a simple method of plaque risk stratification.

Heterogeneous plaque geometry is associated with major adverse cardiovascular events

Objectives

To determine whether coronary artery plaque-lumen geometry predicts major adverse cardiovascular events (MACE), and incorporating geometric measures enhances risk stratification from intravascular imaging.

Background

Prospective studies show that only a minority of plaques with higher-risk features result in future MACE, indicating the need for more predictive markers of plaque vulnerability. Plaques show heterogeneous structures and plaque-lumen geometry, both of which can promote high plaque structural stress (PSS); however, the relationships between geometric heterogeneity and MACE or PSS are unknown.

Methods

We examined plaque-lumen curvature, irregularity, lumen aspect ratio (LAR), roughness, PSS and their longitudinal heterogeneity (Figure 1A) in 35 non-culprit lesions (NCL) associated with MACE and 66 propensity-matched no-MACE NCL from the PROSPECT (Providing Regional Observations to Study Predictors of Events in the Coronary Tree) study. Causes of heterogeneous geometry and PSS were examined using a separate group of co-registered virtual histology-intravascular ultrasound (VH-IVUS) and optical coherence tomography (OCT) images (n=53 plaques).

Results

Plaque geometry heterogeneity indices (HI) were increased in NCL MACE vs. no-MACE lesions across the whole plaque and peri-minimal luminal area (MLA) segments (HI curvature: p=0.002; HI irregularity: p&lt;0.001; HI LAR: p=0.001; HI roughness: p=0.002). Peri-MLA HI roughness was an independent predictor of future MACE (hazard ratio: 3.69, p&lt;0.001) (Figure 1B). Inclusion of HI roughness improved identification of NCLs leading to MACE in VH-defined thin-cap fibroatheromas (VH-TCFA, p=0.005), MLA ≤4mm2 (p=0.001), and plaque burden (PB) ≥70% (p&lt;0.001) (Figure 1C–E), and further improved the ability of PSS to identify MACE NCLs in VH-TCFA (p=0.041), MLA ≤4mm2 (p=0.033), and PB ≥70% (p&lt;0.001). HI roughness generally corresponded with HI PSS, but was also increased at sites of local calcification and multilayering.

Conclusions

Plaque-lumen geometric heterogeneity is increased across whole plaque and peri-MLA segments of NCLs causing MACE. Inclusion of geometric heterogeneity may improve the ability of intravascular imaging to predict MACE.

Funding Acknowledgement

Type of funding sources: Other. Main funding source(s): British Heart Foundation

Angiography derived assessment of the coronary microcirculation: is it ready for prime time?

INTRODUCTION

Non-obstructive coronary arteries (NOCA) are present in 39.7% to 62.4% of patients who undergo elective angiography. Coronary microcirculation (<400 µm) is not visible on angiography therefore functional assessment, invasive or non-invasive plays a prior role to help provide a more personalized diagnosis of angina.

AREA COVERED

In this review, we revise the pathophysiology, clinical importance and invasive assessment of the coronary microcirculation, and discuss angiography-derived indices of microvascular resistance. A comprehensive literature review over four decades is also undertaken.

EXPERT OPINION

The coronary microvasculature plays an important role in flow autoregulation and metabolic regulation. Invasive assessment of microvascular resistance is a validated modality with independent prognostic value, nevertheless, its routine application is hampered by the requirement of intravascular instrumentation and hyperaemic agents. The angiography-derived index of microvascular resistance has emerged as a promising surrogate in pilot studies, however, more data are needed to validate and compare the diagnostic and prognostic accuracy of different equations as well as to illustrate the relationship between angiography-derived parameters for epicardial coronary arteries and those for the microvasculature.

Prophylaxis for Venous Thromboembolic Events in Elective Total Hip and Total Knee Arthroplasty

Venous thromboembolism (VTE) is a serious complication after major orthopaedic operations, such as a total hip (THA) and knee (TKA) arthroplasty. Therefore, perioperative VTE prophylaxis is recommended; a multitude of modern options are available, including both pharmacologic (aspirin, unfractionated and lowmolecular-weight heparin, vitamin K antagonists, and novel oral anticoagulants) and/or mechanical interventions (early mobilization, graduated compression stockings, intermittent pneumatic compression devices, and venous foot pumps). However, because of the abundance of these possibilities, it is crucial to understand the benefits and drawbacks of each VTE prophylaxis option to ensure that the optimal treatment plan is developed for each patient. The American College of Chest Physicians (AACP) and the American Academy of Orthopaedic Surgeons (AAOS) have both published individual guidelines on VTE prophylaxis regimens, alongside numerous studies evaluating the efficacy and outcomes of the different prophylaxis modalities. The purpose of this review is to provide a summary of the evidence on VTE prophylaxis after elective total hip and knee arthroplasty based on current guidelines and highlight the major concerns and potential complications.

Investigating consultant-led virtual review as a model for implementing 7-day cardiology services in UK clinical practice

Background

Disparities between weekend and weekday care, termed 'the weekend effect', have led to a UK government pledge to provide 7-day services. Despite this, poor outcomes have led to criticism of the programme. This study consequently sought to evaluate consultant-led virtual review as a model for 7-day cardiology services.

Methods

Over 4 weekends, cardiology patients underwent virtual review alongside in-person teams. Outcomes included length of stay, same-day discharge and 30-day mortality rates, as well as duration of ward rounds and change in patient management. Patients were surveyed on attitudes towards virtual review.

Results

Statistical analysis revealed no significant difference in clinical outcomes, while virtual review was noted to significantly decrease time taken (p<0.0001). Attitudes towards virtual review were broadly favourable.

Conclusion

By demonstrating comparable outcomes compared with conventional review, as well as high acceptability, this study identified virtual review as an effective substitute for in-person care.

High-intensity statin treatment is associated with reduced plaque structural stress and remodelling of artery geometry and plaque architecture

Aims

Plaque structural stress (PSS) is a major cause of atherosclerotic plaque rupture and major adverse cardiovascular events (MACE). We examined the predictors of changes in peak and mean PSS (ΔPSSpeak, ΔPSSmean) in three studies of patients receiving either standard medical or high-intensity statin (HIS) treatment.

Methods and results

We examined changes in PSS, plaque size, and composition between 7348 co-registered baseline and follow-up virtual-histology intravascular ultrasound images in patients receiving standard medical treatment (controls, n = 18) or HIS (atorvastatin 80 mg, n = 20, or rosuvastatin 40 mg, n = 22). The relationship between changes in PSSpeak and plaque burden (PB) differed significantly between HIS and control groups (P < 0.001). Notably, PSSpeak increased significantly in control lesions with PB >60% (P = 0.04), but not with HIS treatment. However, ΔPSSpeak correlated poorly with changes in lumen and plaque area or PB, plaque composition, or lipid lowering. In contrast, ΔPSSpeak correlated significantly with changes in lumen curvature, irregularity, and roughness (P < 0.05), all of which were reduced in HIS patients. ΔPSSmean correlated with changes in lumen area, PA, PB, and circumferential calcification, and was unchanged with either treatment.

Conclusion

Our observational study shows that PSSpeak changes over time were associated with baseline disease severity and treatment. The PSSpeak increase seen in advanced lesions with standard treatment was associated with remodelling artery geometry and plaque architecture, but this was not seen after HIS treatment. Smoothing plaques by reducing plaque/lumen roughness, irregularity, and curvature represents a novel mechanism whereby HIS may reduce PSS and, thus may protect against plaque rupture and MACE.

Multi-modality intravascular imaging for guiding coronary intervention and assessing coronary atheroma: the Novasight Hybrid IVUS-OCT system

Intravascular imaging has evolved alongside interventional cardiology as an adjunctive tool for assessing plaque pathology and for guiding and optimising percutaneous coronary intervention (PCI) in challenging lesions. The two modalities which have dominated the field are intravascular ultrasound (IVUS), which relies on sound waves and optical coherence tomography (OCT), relying on light waves. These approaches however have limited efficacy in assessing plaque morphology and vulnerability that are essential for guiding PCI in complex lesions and identifying patient at risk that will benefit from emerging therapies targeting plaque evolution. These limitations are complementary and, in this context, it has been recognised and demonstrated in multi-modality studies that the concurrent use of IVUS and OCT can help overcome these deficits enabling a more complete and accurate plaque assessment. The Conavi Novasight Hybrid IVUS-OCT catheter is the first commercially available device that is capable of invasive clinical coronary assessment with simultaneously acquired and co-registered IVUS and OCT imaging. It represents a significant evolution in the field and is expected to have broad application in clinical practice and research. In this review article we present the limitations of standalone intravascular imaging techniques, summarise the data supporting the value of multimodality imaging in clinical practice and research, describe the Novasight Hybrid IVUS-OCT system and highlight the potential utility of this technology in coronary intervention and in the study of atherosclerosis.

Optical Coherence Tomography based treatment approach for patients with Acute Coronary Syndrome

INTRODUCTION

Areas covered:In this review, we outline the underlying causes of acute coronary syndrome (ACS) as evaluated by optical coherence tomography (OCT). We report both the definitions of each mechanism and its frequency as reported in the literature to date. Finally, we present an algorithm based on the findings in the review that gives an outlined approach to perform intervention on ACS patients.Expert opinion:Although the most common and most accepted intervention in ACS cases is stent implantation, data suggest a stentless approach in cases of plaque erosion, which generally occurs in younger patients presenting with an acute coronary syndrome that have TIMI flow of 2/3 and either a small or large burden of thrombus and underlying stenosis of less than 50%.

Clinical use of intracoronary imaging. Part 2: acute coronary syndromes, ambiguous coronary angiography findings, and guiding interventional decision-making: an expert consensus document of the European Association of Percutaneous Cardiovascular Interventions

This consensus document is the second of two reports summarizing the views of an expert panel organized by the European Association of Percutaneous Cardiovascular Interventions (EAPCI) on the clinical use of intracoronary imaging including intravascular ultrasound (IVUS), optical coherence tomography (OCT), and near infrared spectroscopy (NIRS)-IVUS. Beyond guidance of stent selection and optimization of deployment, invasive imaging facilitates angiographic interpretation and may guide treatment in acute coronary syndrome. Intravascular imaging can provide additional important diagnostic information when confronted with angiographically ambiguous lesions and allows assessment of plaque morphology enabling identification of vulnerability characteristics. This second document focuses on useful imaging features to identify culprit and vulnerable coronary plaque, which offers the interventional cardiologist guidance on when to adopt an intracoronary imaging-guided approach to the treatment of coronary artery disease and provides an appraisal of intravascular imaging-derived metrics to define the haemodynamic significance of coronary lesions.

Advances in IVUS/OCT and Future Clinical Perspective of Novel Hybrid Catheter System in Coronary Imaging

Intravascular ultrasound (IVUS) and optical coherence tomography (OCT) have been developed and improved as both diagnostic and guidance tools for interventional procedures over the past three decades. IVUS has a resolution of 100 μm with a high tissue penetration and capability of assessing the entire structure of a coronary artery including the external elastic membrane, whereas OCT has a higher resolution of 10–20 μm to assess endoluminal structures with a limited tissue penetration compared to IVUS. Recently, two companies, CONAVI and TERUMO, integrated IVUS and OCT into a single catheter system. With their inherent strength and limitations, the combined IVUS and OCT probes are complementary and work synergistically to enable a comprehensive depiction of coronary artery. In this review, we summarize the performance of the two intracoronary imaging modalities—IVUS and OCT—and discuss the expected potential of the novel hybrid IVUS–OCT catheter system in the clinical field.

Prediction of atherosclerotic disease progression combining computational modelling with machine learning

Non-invasive serial computed tomography coronary angiography (CTCA) was acquired from 32 patients and 3D reconstruction of 58 coronary arteries was achieved. The arterial geometries were utilized for blood flow and LDL transport modelling. Navier-Stokes and convection-diffusion equations were employed for simulation of blood flow and LDL transport, respectively. Disease progression was assessed comparing the follow-up and baseline arterial models after co-registration using side branches as anatomical landmarks. A machine learning model for predicting disease progression was built using the Gradient Boosted Trees (GBT) algorithm. The Accuracy, Sensitivity, Specificity and AUC of the developed methodology for predicting lumen area decrease equal was 0.68, 0.56, 0.34 and 0.59, respectively. The best results were found for the prediction of plaque area increase by 20%, with 0.73, 0.67, 0.86, and 0.76 accuracy, sensitivity, specificity andAUC, respectively. This approach outperforms significantly the predictive capability of models based on binary logistic regression.

P5631The impact of plaque type on strut embedment/protrusion and shear stress distribution in bioresorbable scaffold

Background and aim

Scaffold design and plaque characteristics influence implantation outcomes and local flow dynamics in treated coronary segments. Our aim is to assess the impact of strut embedment/protrusion of bioresorbable scaffold on local shear stress distribution in different atherosclerotic plaque types.

Method

Fifteen Absorb everolimus-eluting Bioresorbable Vascular Scaffolds were implanted in human epicardial coronary arteries. Optical coherence tomography (OCT) was performed post-scaffold implantation and strut embedment/protrusion were analyzed using a dedicated software. OCT data was fused with angiography to reconstruct three-dimensional coronary anatomy. Blood flow simulation was performed and wall shear stress (WSS) was estimated in each scaffolded surface and the relationship between strut embedment/protrusion and WSS was evaluated.

Results

There were 9083 struts analysed. Ninety-seven percent of the struts (n=8840) were well apposed and 243 (3%) were malapposed. At cross-section level (n=1289), strut embedment was significantly increased in fibroatheromatous plaques (76±48μm) and decreased in fibro-calcific plaques (35±52 μm). Compatible with strut embedment, WSS was significantly higher in lipid-rich fibroatheromatous plaques (1.50±0.81Pa), whereas significantly decreased in fibro-calcified plaques (1.05±0.91Pa). After categorization of WSS as low (<1.0 Pa) and normal/high WSS (≥1.0 Pa), the percent of low-WSS in the plaque subgroups were 30.1%, 31.1%, 25.4% and 36.2% for non-diseased vessel wall, fibrous plaque, fibro-atheromatous plaque and fibro-calcific plaque, respectively (p-overall<0.001).

Table 1. Cross-section level Embedment/Protrusion and WSS according to the plaque type Plaque type Embedment depth (μm) Protrusion distance (μm) WSS (Pa) Non-atherosclerotic intimal thickening/normal vessel wall (n=2275) 47±34*Δ¥ 123±34¶Ξπ 1.44±0.9解 Fibrous (n=4191) 53±40*#& 118±38¶Ψ‡ 1.24±0.78αθ∞ Fibroatheromatous (n=2027) 76±48#ΦΔ 94.6±46Ω†Ψπ 1.50±0.81Σ§α Fibro-calcific (n=590) 35±52&Φ¥ 139±50‡†Ξ 1.05±0.91∞£Σ For embedment: *p=0.09, #p<0.001, &p<0.001, Φp<0.0001, Δp<0.0001, ¥p<0.0001. For protrusion: ¶p=0.74, Ξp<0.0001, πp<0.0001, Ψp<0.0001, ‡p<0.0001, †p<0.0001. For WSS: θp<0.001, §p=0.06, £p<0.0001, αp<0.0001, ∞p<0.0001, Ωp<0.0001. n=total strut number in each plaque type, p-values come from mixed-effects regression analysis.

Conclusion

The composition of the underlying plaque influences strut embedment which seems to have effect on WSS. The struts deeply embedded in lipid-rich fibroatheromas plaques resulted in higher WSS compared to the other plaque types.

P869Predictive value of the endothelial shear stress distribution in three-dimensional quantitative coronary angiography models in detecting vulnerable plaques

Background

Low Endothelial shear stress (ESS) is a well-known instigator of coronary atherosclerosis. Prospective intravascular ultrasound (IVUS)-based imaging studies with computational fluid dynamic analysis revealed its predictive merit in-vivo. However, whether coronary modelling derived from quantitative coronary angiography (QCA) is equally effective in detecting high-risk plaques remains to be established.

Purpose

To examine the value of endothelial shear stress (ESS) estimated in three-dimensional (3D) QCA models in detecting plaques that are likely to progress and cause events.

Method

We analysed the baseline intravascular ultrasound virtual histology (IVUS-VH) and angiographic data from 28 non-culprit lesions with a vulnerable phenotype (i.e., fibroatheroma or thin cap fibroatheroma) that caused major adverse cardiac events or required revascularization (nc-MACE-R) at 5-year follow-up and from a control group of 119 vulnerable plaques that remained quiescent. The segments studied by IVUS-VH at baseline were reconstructed using 3D-QCA software and in the obtained geometries blood flow simulation was performed and we estimated the resting Pd/Pa across the vulnerable plaque and the mean ESS values in 3mm sub-segments. A propensity score was built by the baseline plaque characteristics and the hemodynamic indices and its efficacy in detecting nc-MACE-R lesions was examined.

Results

Nc-MACE-R lesions were longer (32.5mm [18.0, 41.6], vs. 19.6mm [12.7, 31.3], p=0.03), had smaller minimum lumen area (MLA) (3.65mm2 [3.26, 4.36] vs. 5.03mm2 [3.98, 6.66], p<0.01), increased plaque burden (PB) (69.4% [63.5, 72.0] vs. 60.8% [53.7, 66.5], p<0.01), were exposed to higher ESS (9.40Pa [6.3, 12.5] vs. 4.1Pa [3.0, 6.9], p<0.01), and exhibited a lower resting Pd/Pa (0.97 [0.95, 0.98] vs. 0.98 [0.97, 0.99], p<0.01]. In multivariable analysis the only independent predictor of nc-MACE-R was the maximum 3mm ESS value (hazard ratio: 1.08 [1.02, 1.16], P=0.016). Lesions exposed to high ESS (>4.95Pa) with a high-risk anatomy (MLA<4mm2and PB>70%) had a higher nc-MACE-R rate (53.8%) than those with a low-risk anatomy exposed to high ESS (31.6%) or those exposed to low ESS that had high (20.0%) or low-risk anatomy (7.1%, P<0.001).

Conclusion

In the present study, 3D-QCA-derived local hemodynamic variables provided useful prognostic information and in combination with lesion anatomy enabled more accurate identification of nc-MACE-R lesions. Further research in a larger number of patients is need to confirm these findings before the conduction of large scale prospective studies that will combine intravascular imaging and 3D-QCA modelling to more accurately detect vulnerable plaques.

Quantitative myocardial perfusion in coronary artery disease: A perfusion mapping study

BACKGROUND

Cardiac MR stress perfusion remains a qualitative technique in clinical practice due to technical and postprocessing challenges. However, automated inline perfusion mapping now permits myocardial blood flow (MBF, ml/g/min) quantification on-the-fly without user input.

PURPOSE

To investigate the diagnostic performance of this novel technique in detecting occlusive coronary artery disease (CAD) in patients scheduled to undergo coronary angiography.

STUDY TYPE

Prospective, observational.

SUBJECTS

Fifty patients with suspected CAD and 24 healthy volunteers.

FIELD STRENGTH

1.5T. SEQUENCE: "Dual" sequence multislice 2D saturation recovery.

ASSESSMENT

All patients underwent cardiac MR with perfusion mapping and invasive coronary angiography; the healthy volunteers had MR with perfusion mapping alone.

STATISTICAL TESTS

Comparison between numerical variables was performed using an independent t-test. Receiver operator characteristic (ROC) curves were generated for transmyocardial, endocardial stress MBF, and myocardial perfusion reserve (MPR, the stress:rest MBF ratio) to diagnose severe (>70%) stenoses as measured by 3D quantitative coronary angiography (QCA). ROC curves were compared by the method of DeLong et al. RESULTS: Compared with volunteers, patients had lower stress MBF and MPR even in vessels with <50% stenosis (2.00 vs. 3.08 ml/g/min, respectively). As stenosis severity increased (<50%, 50-70%, >70%), MBF and MPR decreased. To diagnose occlusive (>70%) CAD, endocardial and transmyocardial stress MBF were superior to MPR (area under the curve 0.92 [95% CI 0.86-0.97] vs. 0.90 [95% CI 0.84-0.95] and 0.80 [95% CI 0.72-0.87], respectively). An endocardial threshold of 1.31 ml/g/min provided a per-coronary artery sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of 90%, 82%, 50%, and 98%, with a per-patient diagnostic performance of 100%, 66%, 57%, and 100%, respectively.

DATA CONCLUSION

Perfusion mapping can diagnose occlusive CAD with high accuracy and, in particular, high sensitivity and NPV make it a potential "rule-out" test.

LEVEL OF EVIDENCE

1 Technical Efficacy Stage: 2 J. Magn. Reson. Imaging 2019;50:756-762.

Strut protrusion and shape impact on endothelial shear stress: insights from pre-clinical study comparing Mirage and Absorb bioresorbable scaffolds

Protrusion of scaffold struts is related with local coronary flow dynamics that can promote scaffold restenosis and thrombosis. That fact has prompted us to investigate in vivo the protrusion status of different types of scaffolds and their relationship with endothelial shear stress (ESS) distributions. Six Absorb everolimus-eluting Bioresorbable Vascular Scaffolds (Absorb, Abbott Vascular) and 11 Mirage sirolimus-eluting Bioresorbable Microfiber Scaffolds (Mirage, Manli Cardiology) were implanted in coronaries of eight mini pigs. Optical coherence tomography (OCT) was performed post-scaffold implantation and obtained images were fused with angiographic data to reconstruct the three dimensional coronary anatomy. Blood flow simulation was performed and ESS distribution was estimated for each scaffold. Protrusion distance was estimated using a dedicated software. Correlation between OCT-derived protrusion and ESS distribution was assessed for both scaffold groups. A significant difference was observed in the protrusion distances (156 ± 137 µm for Absorb, 139 ± 153 µm for Mirage; p = 0.035), whereas difference remained after adjusting the protrusion distances according to the luminal areas. Strut protrusion of Absorb is inversely correlated with ESS (r = −0.369, p < 0.0001), whereas in Mirage protrusion was positively correlated with EES (r = 0.192, p < 0.0001). Protrusion distance was higher in Absorb than in Mirage. The protrusion of the thick quadratic struts of Absorb has a tendency to lower shear stress in the close vicinity of struts. However, circular shape of the less thick struts of Mirage didn’t show this trend in creating zone of recirculation around the struts. Strut geometry has different effect on the relationship between protrusion and shear stress in Absorb and Mirage scaffolds.