Sortilin enhances fibrosis and calcification in aortic valve disease by inducing interstitial cell heterogeneity.

AIMS: Calcific aortic valve disease (CAVD) is the most common valve disease, which consists of a chronic interplay of inflammation, fibrosis, and calcification. In this study, sortilin (SORT1) was identified as a novel key player in the pathophysiology of CAVD, and its role in the transformation of valvular interstitial cells (VICs) into pathological phenotypes is explored. METHODS AND RESULTS: An aortic valve (AV) wire injury (AVWI) mouse model with sortilin deficiency was used to determine the effects of sortilin on AV stenosis, fibrosis, and calcification. In vitro experiments employed human primary VICs cultured in osteogenic conditions for 7, 14, and 21 days; and processed for imaging, proteomics, and transcriptomics including single-cell RNA-sequencing (scRNA-seq). The AVWI mouse model showed reduced AV fibrosis, calcification, and stenosis in sortilin-deficient mice vs. littermate controls. Protein studies identified the transition of human VICs into a myofibroblast-like phenotype mediated by sortilin. Sortilin loss-of-function decreased in vitro VIC calcification. ScRNA-seq identified 12 differentially expressed cell clusters in human VIC samples, where a novel combined inflammatory myofibroblastic-osteogenic VIC (IMO-VIC) phenotype was detected with increased expression of SORT1, COL1A1, WNT5A, IL-6, and serum amyloid A1. VICs sequenced with sortilin deficiency showed decreased IMO-VIC phenotype. CONCLUSION: Sortilin promotes CAVD by mediating valvular fibrosis and calcification, and a newly identified phenotype (IMO-VIC). This is the first study to examine the role of sortilin in valvular calcification and it may render it a therapeutic target to inhibit IMO-VIC emergence by simultaneously reducing inflammation, fibrosis, and calcification, the three key pathological processes underlying CAVD.

Safety and efficiency of percutaneous coronary intervention using a standardised optical coherence tomography workflow.

BACKGROUND: While intravascular imaging guidance during percutaneous coronary intervention (PCI) improves outcomes, routine intravascular imaging usage remains low, in part due to perceived inefficiency and safety concerns.  Aims: The LightLab (LL) Initiative was designed to evaluate whether implementing a standardised optical coherence tomography (OCT) workflow impacts PCI safety metrics and procedural efficiency. METHODS: In this multicentre, prospective, observational study, PCI procedural data were collected over 2 years from 45 physicians at 17 US centres. OCT-guided PCI incorporating the LL workflow (N=264), a structured algorithm using routine pre- and post-PCI OCT imaging, was compared with baseline angiography-only PCI (angio) (N=428). Propensity score analysis identified 207 matched procedures. Outcomes included procedure time, radiation exposure, contrast volume, device utilisation, and treatment strategy. RESULTS: Compared with angiography alone, LL workflow OCT-guided PCI increased the median procedural time by 9 minutes but reduced vessel preparation time (2 min LL workflow vs 3 min angio; p<0.001) and resulted in less unplanned additional treatment (4% LL workflow vs 10% angio; p=0.01). With LL workflow OCT guidance, fewer cineangiography views were needed compared to angiography guidance, leading to decreased radiation exposure (1,133 mGy LL workflow vs 1,269 mGy angio; p=0.02), with no difference in contrast utilisation between groups (p=0.28). Furthermore, LL workflow OCT guidance resulted in fewer predilatation balloons and stents being used, more direct stent placement, and greater stent post-dilatation than angiography-guided PCI. CONCLUSIONS: The incorporation of a standardised pre- and post-PCI OCT imaging workflow improves procedural efficiency and safety metrics, at a cost of a modestly longer procedure time.

OCT utilization: Summary statistics from the LightLab clinical initiative.

OBJECTIVES: The study describes the evolution of optical coherence tomography (OCT) adoption and performance during percutaneous coronary intervention (PCI) following implementation of a standardized LightLab (LL) workflow. BACKGROUND: The purpose of the LL Clinical Initiative was to evaluate the impact of a standardized workflow on physician efficiency, decision making, and image quality. METHODS: The LL Clinical Initiative is a multicenter, prospective, observational clinical program. Data were collected from 48 physicians at 17 U.S. centers from 01/21/19 to 06/08/21. The study included 401 OCT-guided PCIs during the baseline phase and 1898 during the LL workflow phases. The baseline phase consisted of physicians utilizing OCT at their discretion. After completing the baseline phase, the workflow progressed through multiple phases culminating in the expansion phase, which focused on addressing greater procedural complexity. The LL workflow utilized OCT to assess plaque Morphology, lesion Length, and vessel Diameter before PCI, and optimized results by treating Medial edge dissection, stent mal-Apposition, and stent under-eXpansion (MLD MAX). High-level summary statistics were generated to elucidate trends. RESULTS: After program implementation, there was a rise in the number of PCIs where the LL workflow was utilized compared to the baseline phase (68% during the expansion phase vs. 41% at baseline; p for trend <0.0001). Adoption of the LL workflow was associated with progressively greater procedural and lesion complexity when OCT was performed pre- and post-PCI (87% vs. 52%, p < 0.0001; 55% vs. 37%, p < 0.0001, respectively). In addition, the quality of OCT imaging obtained improved after LL workflow introduction, with over 95% of pre- and post-PCI pullback quality considered usable during the expansion phase. Finally, there was a reduction in time spent on OCT interpretation, both pre-PCI (4.6 min vs. 7.5 min, p < 0.0001) and post-PCI (2.9 min vs. 5.3 min, p < 0.0001). CONCLUSIONS: After completion of the standardized OCT-guided workflow, there was greater uptake of OCT imaging, incorporation in more complex procedures, procedural efficiency, and image quality.

Highly Selective PPARα (Peroxisome Proliferator-Activated Receptor α) Agonist Pemafibrate Inhibits Stent Inflammation and Restenosis Assessed by Multimodality Molecular-Microstructural Imaging.

BACKGROUND New pharmacological approaches are needed to prevent stent restenosis. This study tested the hypothesis that pemafibrate, a novel clinical selective PPARα (peroxisome proliferator-activated receptor α) agonist, suppresses coronary stent-induced arterial inflammation and neointimal hyperplasia. METHODS AND RESULTS Yorkshire pigs randomly received either oral pemafibrate (30 mg/day; n=6) or control vehicle (n=7) for 7 days, followed by coronary arterial implantation of 3.5 × 12 mm bare metal stents (2-4 per animal; 44 stents total). On day 7, intracoronary molecular-structural near-infrared fluorescence and optical coherence tomography imaging was performed to assess the arterial inflammatory response, demonstrating that pemafibrate reduced stent-induced inflammatory protease activity (near-infrared fluorescence target-to-background ratio: pemafibrate, median [25th-75th percentile]: 2.8 [2.5-3.3] versus control, 4.1 [3.3-4.3], P=0.02). At day 28, animals underwent repeat near-infrared fluorescence-optical coherence tomography imaging and were euthanized, and coronary stent tissue molecular and histological analyses. Day 28 optical coherence tomography imaging showed that pemafibrate significantly reduced stent neointima volume (pemafibrate, 43.1 [33.7-54.1] mm3 versus control, 54.2 [41.2-81.1] mm3; P=0.03). In addition, pemafibrate suppressed day 28 stent-induced cellular inflammation and neointima expression of the inflammatory mediators TNF-α (tumor necrosis factor-α) and MMP-9 (matrix metalloproteinase 9) and enhanced the smooth muscle differentiation markers calponin and smoothelin. In vitro assays indicated that the STAT3 (signal transducer and activator of transcription 3)-myocardin axes mediated the inhibitory effects of pemafibrate on smooth muscle cell proliferation. CONCLUSIONS Pemafibrate reduces preclinical coronary stent inflammation and neointimal hyperplasia following bare metal stent deployment. These results motivate further trials evaluating pemafibrate as a new strategy to prevent clinical stent restenosis.

Paclitaxel Drug-Coated Balloon Angioplasty Suppresses Progression and Inflammation of Experimental Atherosclerosis in Rabbits.

Paclitaxel drug-coated balloons (DCBs) reduce restenosis, but their overall safety has recently raised concerns. This study hypothesized that DCBs could lessen inflammation and reduce plaque progression. Using 25 rabbits with cholesterol feeding- and balloon injury-induced lesions, DCB-percutaneous transluminal angioplasty (PTA), plain PTA, or sham-PTA (balloon insertion without inflation) was investigated using serial intravascular near-infrared fluorescence-optical coherence tomography and serial intravascular ultrasound. In these experiments, DCB-PTA reduced inflammation and plaque burden in nonobstructive lesions compared with PTA or sham-PTA. These findings indicated the potential for DCBs to serve safely as regional anti-atherosclerosis therapy.

Intravascular Ultrasound Imaging-Guided Versus Coronary Angiography-Guided Percutaneous Coronary Intervention: A Systematic Review and Meta-Analysis.

Background Intravascular ultrasound (IVUS) guidance during percutaneous coronary intervention (PCI) offers tomographic images of the coronary vessels, allowing optimization of stent implantation at the time of PCI. However, the long-term beneficial effect of IVUS over PCI guided by coronary angiography (CA) alone remains under question. We sought to investigate the outcomes of IVUS-guided compared with CA-guided PCI. Methods and Results We performed a comprehensive search of PubMed, Medline, and Cochrane Central Register, looking for randomized controlled trials and observational studies that compared PCI outcomes of IVUS with CA. Data were aggregated for the primary outcome measure using the random-effects model as pooled risk ratio (RR). The primary outcomes were the rate of cardiovascular death, need for target lesion revascularization, occurrence of myocardial infarction, and rate of stent thrombosis. A total of 19 studies met the inclusion criteria, comprising 27 610 patients divided into IVUS (n=11 513) and CA (n=16 097). Compared with standard CA-guided PCI, we found that the risks of cardiovascular death (RR, 0.63; 95% CI, 0.54-0.73), myocardial infarction (RR, 0.71; 95% CI, 0.58-0.86), target lesion revascularization (RR, 0.81; 95% CI, 0.70-0.94), and stent thrombosis (RR, 0.57; 95% CI, 0.41-0.79) were all significantly lower using IVUS guidance. Conclusions Compared with standard CA-guided PCI, the use of IVUS imaging guidance to optimize stent implantation is associated with a reduced risk of cardiovascular death and major adverse events, such as myocardial infarction, target lesion revascularization, and stent thrombosis.

Physiological Assessment of Coronary Lesions in 2020.

PURPOSE OF REVIEW: Physiological assessment of coronary artery disease (CAD) is an essential component of the interventional cardiology toolbox. However, despite long-term data demonstrating improved outcomes, physiology-guided percutaneous coronary intervention (PCI) remains underutilized in current practice. This review outlines the indications and technical aspects involved in evaluating coronary stenosis physiology, focusing on the latest developments in the field. RECENT FINDINGS: Beyond fractional flow reserve (FFR), non-hyperemic pressure ratios (NHPR) that assess coronary physiology at rest without hyperemia now abound. Additional advances in other alternative FFR approaches, including non-invasive coronary CT (FFRCT), invasive angiography (FFRangio), and optical coherence tomography (FFROCT), are being realized. Artificial intelligence algorithms and robust tools that enable detailed pre-procedure "virtual" intervention are also emerging. The benefits of coronary physiological assessment to determine lesion functional significance are well established. In addition to stable CAD, coronary physiology can be especially helpful in clinical scenarios such as left main and multivessel CAD, serial lesions, non-infarct-related arteries in acute coronary syndromes, and residual ischemia post-PCI. Today, coronary physiological assessment remains an indispensable tool in the catheterization laboratory, with an exciting technological future that will further refine clinical practice and improve patient care.

Chest Pain During Chemotherapy: A Case of Severe Myocardial Bridging.

A cancer patient presented with acute chest pain at rest 40 hours after IV fluorouracil infusion. Angiography showed evidence of myocardial bridging.

Metabolic and Molecular Imaging of Atherosclerosis and Venous Thromboembolism.

Metabolic and molecular imaging continues to advance our understanding of vascular disease pathophysiology. At present, 18F-FDG PET imaging is the most widely used clinical tool for metabolic and molecular imaging of atherosclerosis. However, novel nuclear tracers and intravascular optical near-infrared fluorescence imaging catheters are emerging to assess new biologic targets in vivo and in coronary arteries. This review highlights current metabolic and molecular imaging clinical and near-clinical applications within atherosclerosis and venous thromboembolism, and explores the potential for metabolic and molecular imaging to affect patient-level risk prediction and disease treatment.

Quantitative intravascular biological fluorescence-ultrasound imaging of coronary and peripheral arteries in vivo.

AIMS: (i) to evaluate a novel hybrid near-infrared fluorescence-intravascular ultrasound (NIRF-IVUS) system in coronary and peripheral swine arteries in vivo; (ii) to assess simultaneous quantitative biological and morphological aspects of arterial disease. METHODS AND RESULTS: Two 9F/15MHz peripheral and 4.5F/40MHz coronary near-infrared fluorescence (NIRF)-IVUS catheters were engineered to enable accurate co-registrtation of biological and morphological readings simultaneously in vivo. A correction algorithm utilizing IVUS information was developed to account for the distance-related fluorescence attenuation due to through-blood imaging. Corrected NIRF (cNIRF)-IVUS was applied for in vivo imaging of angioplasty-induced vascular injury in swine peripheral arteries and experimental fibrin deposition on coronary artery stents, and of atheroma in a rabbit aorta, revealing feasibility to intravascularly assay plaque structure and inflammation. The addition of ICG-enhanced NIRF assessment improved the detection of angioplasty-induced endothelial damage compared to standalone IVUS. In addition, NIRF detection of coronary stent fibrin by in vivo cNIRF-IVUS imaging illuminated stent pathobiology that was concealed on standalone IVUS. Fluorescence reflectance imaging and microscopy of resected tissues corroborated the in vivo findings. CONCLUSIONS: Integrated cNIRF-IVUS enables simultaneous co-registered through-blood imaging of disease related morphological and biological alterations in coronary and peripheral arteries in vivo. Clinical translation of cNIRF-IVUS may significantly enhance knowledge of arterial pathobiology, leading to improvements in clinical diagnosis and prognosis, and helps to guide the development of new therapeutic approaches for arterial diseases.

Targeted Near-Infrared Fluorescence Imaging of Atherosclerosis: Clinical and Intracoronary Evaluation of Indocyanine Green.

OBJECTIVES: This study sought to determine whether indocyanine green (ICG)-enhanced near-infrared fluorescence (NIRF) imaging can illuminate high-risk histologic plaque features of human carotid atherosclerosis, and in coronary atheroma of living swine, using intravascular NIRF-optical coherence tomography (OCT) imaging. BACKGROUND: New translatable imaging approaches are needed to identify high-risk biological signatures of atheroma. ICG is a U.S. Food and Drug Administration-approved NIRF imaging agent that experimentally targets plaque macrophages and lipid in areas of enhanced endothelial permeability. However, it is unknown whether ICG can target atheroma in patients. METHODS: Eight patients were enrolled in the BRIGHT-CEA (Indocyanine Green Fluorescence Uptake in Human Carotid Artery Plaque) trial. Five patients were injected intravenously with ICG 99 ± 25 min before clinically indicated carotid endarterectomy. Three saline-injected endarterectomy patients served as control subjects. Excised plaques underwent analysis by intravascular NIRF-OCT, reflectance imaging, microscopy, and histopathology. Next, following ICG intravenous injection, in vivo intracoronary NIRF-OCT and intravascular ultrasound imaged 3 atheroma-bearing coronary arteries of a diabetic, cholesterol-fed swine. RESULTS: ICG was well tolerated; no adverse clinical events occurred up to 30 days post-injection. Multimodal NIRF imaging including intravascular NIRF-OCT revealed that ICG accumulated in all endarterectomy specimens. Plaques from saline-injected control patients exhibited minimal NIRF signal. In the swine experiment, intracoronary NIRF-OCT identified ICG uptake in all intravascular ultrasound-identified plaques in vivo. On detailed microscopic evaluation, ICG localized to plaque areas exhibiting impaired endothelial integrity, including disrupted fibrous caps, and within areas of neovascularization. Within human plaque areas of endothelial abnormality, ICG was spatially related to localized zones of plaque macrophages and lipid, and, notably, intraplaque hemorrhage. CONCLUSIONS: This study demonstrates that ICG targets human plaques exhibiting endothelial abnormalities and provides new insights into its targeting mechanisms in clinical and experimental atheroma. Intracoronary NIRF-OCT of ICG may offer a novel, clinically translatable approach to image pathobiological aspects of coronary atherosclerosis. (Indocyanine Green Fluorescence Uptake in Human Carotid Artery Plaque [BRIGHT-CEA]; NCT01873716).

Imaging inflammation and neovascularization in atherosclerosis: clinical and translational molecular and structural imaging targets.

PURPOSE OF REVIEW: The purpose of this study is to showcase advances in molecular imaging of atheroma biology in living individuals. RECENT FINDINGS: F-fluorodeoxyglucose (FDG) PET/computed tomography (CT) continues to be the predominant molecular imaging approach for clinical applications, particularly in the large arterial beds. Recently, there has been significant progress in imaging of neovascularization and inflammation to delineate high-risk atheroma and to evaluate drug efficacy. In addition, new hardware detection technology and imaging agents are enabling in-vivo imaging of new targets on diverse imaging platforms. SUMMARY: In this review, we present recent exciting developments in molecular and structural imaging of atherosclerotic plaque inflammation and neovascularization. Building upon prior studies, these advances develop key technology that will play an important role in propelling new diagnostic and therapeutic strategies identifying high-risk plaque phenotypes and assessing new plaque stabilization therapies in clinical trials.