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Major advances have been made in coronary artery stent technology over the last decades. Drug-eluting stents reduced in-stent restenosis and have shown better outcomes compared with bare metal stents, yet some limitations still exist to their use. Because they delay healing of the vessel wall, longer dual antiplatelet therapy is mandatory to mitigate against stent thrombosis and this limitation is most concerning in subjects at high risk for bleeding. The COBRA PzF nanocoated coronary stent has been associated with accelerated endothelialization relative to drug-eluting stents, reduced inflammation and thromboresistance in preclinical studies, suggesting more flexible dual antiplatelet therapy requirement with potential benefits especially in those at high bleeding risk. Here, we discuss the significance of COBRA PzF in light of recent experimental and clinical studies.Coronary artery disease occurs when the inner walls of the coronary arteries thicken due to plaque build-up. As the plaque develops, the inside of the artery narrows, and blood flow to the heart muscle is restricted. Coronary stents act as a miniature circular scaffolding that flexes to fit the shape of the artery. In the COBRA PzF nanocoated coronary stent, Polyzene F nanocoating (PzF) has been applied to the stent’s surface. Experimental studies have shown that PzF nanocoatings promote healing after stent implantation and reduce the attachment of platelets and inflammatory cells. The principal safety and effectiveness for the COBRA PzF stent has been proven by clinical studies, showing that the COBRA PzF stent was as safe and effective as other approved bare metal coronary stents. Here, we summarize the findings of experimental and clinical studies with the COBRA PzF stent and discuss potential future directions of anti-platelet and anti-coagulant medications following COBRA PzF stent implantation.

INTRODUCTION Late stent thrombosis caused by delayed vascular healing and prolonged local inflammation were major drawbacks of 1st generation drug-eluting stents (DES). Strut design, biocompatibility of polymer, and drug-release profiles were improved in 2nd and 3rd generation DES. Accordingly, the indications for percutaneous coronary intervention with DES have been expanded to more complex patients and lesions. Despite these improvements, significant barriers such as greater flexibility in the duration of dual-antiplatelet therapy (DAPT) as well as reducing long-term stent-related events remain. To achieve ideal short- and long-term results, these existing limitations need to be overcome. AREAS COVERED We will discuss the current limitations of coronary DES and how they might be overcome from pathological and clinical viewpoints. EXPERT OPINION Optimizing DAPT duration after stent implantation and prevention of in-stent neoatherosclerosis are two major issues in current DES. Overcoming these drawbacks is a prerequisite towards achieving better short- and long-term clinical outcomes. New technologies including platform design, polymer types, and anti-proliferative agent itself might lead to further improvements. Although the initial experience with bioresorbable scaffold/stents (BRS) was disappointing, positive results of clinical studies regarding novel BRS are raising expectations. Overall, further device innovation is desired for overcoming the limitations of current DES.

Background In peripheral artery disease, two different types of calcification are frequently observed, i.e., medial and intimal calcification. Aims The aim of this study was to determine the ability of intravascular ultrasound (IVUS) imaging and optical frequency domain imaging (OFDI) to detect medial and intimal calcification in human peripheral arteries. Methods We performed ex vivo intravascular imaging of cadaveric human peripheral arteries with calcifications. IVUS and OFDI images were co-registered with histology. A total of 12 legs from nine patients were examined, and 438 cross-sectional images were co-registered with histology. Results OFDI could detect 183 of 231 intimal calcifications by histology, whereas IVUS could detect 194 (OFDI: sensitivity 79%, specificity 86%, area under the curve [AUC] 0.83; IVUS: sensitivity 84%, specificity 85%, AUC 0.85). Of 245 medial calcifications by histology, 160 and 164 were detected by OFDI and IVUS, respectively (OFDI: sensitivity 65%, specificity 85%, AUC 0.75; IVUS: sensitivity 67%, specificity 80%, AUC 0.74). Medial calcification with overlying intimal calcification (overlapped calcification) and an unclear border between intima and media were the main reasons for misdiagnosis. Without those 89 overlapped calcifications, sensitivity in both OFDI and IVUS was improved (OFDI: sensitivity 81%, specificity 85%, AUC 0.83; IVUS: sensitivity 88%, specificity 80%, AUC 0.84). Conclusions There are limitations in detecting medial calcification in overlapped intimal calcification and with an unclear border between intima and media by both IVUS and OFDI. It is important to distinguish medial calcification from intimal calcification before proceeding with endovascular therapy since different approaches will be required.

Catheter-based renal denervation is a novel treatment approach for patients with hypertension and initial unblinded trials have shown promising results. The Paradise™ Ultrasound Renal Denervation System (ReCor Medical, CA, USA) is an ultrasound-based catheter with a distal balloon that acts as a coolant to protect the renal arterial wall. This device received CE-mark in 2012. Randomized, sham-controlled trials and postmarket studies have shown promising efficacy and safety results. Currently, three additional ongoing randomized, sham-controlled trials are underway in the USA, Europe, Japan and Korea, and the results will be pivotal in device approval in some of these countries. These studies with larger numbers of patients and longer duration of follow-up are needed to further confirm the safety and efficacy of this device.

Introduction Cerebrovascular events are one of the most serious consequences after transcatheter aortic valve replacement (TAVR). More than half of the cerebrovascular events following TAVR are due to procedure-related emboli. Embolic protection devices (EPDs) have the potential to decrease cerebrovascular events during TAVR procedure. However, randomized controlled trials (RCTs) have not conclusively determined if EPDs are effective, likely because of small number of patients enrolled. However, meta-analyses and propensity-matched analyses from large registries have shown efficacy and suggest the importance of EPDs in prevention of stroke during TAVR and perhaps other structural heart procedures. Areas covered This review will focus on clinical and histopathologic studies examining the efficacy, safety, and histopathologic device capture findings in the presence and absence of EPDs during TAVR procedures. Expert opinion Clinical studies have not conclusively determined the efficacy of EPDs. Current ongoing large-scale RCT (PROTECTED TAVR [NCT04149535]) has the potential to prove their efficacy. Histopathological evaluation of debris captured by EPDs contributes to our understanding of the mechanisms of TAVR procedure-related embolic events and suggests the importance of preventing cerebral embolization of debris released during this and other structural heart procedures.

Objective: Reported associations between kidney risk variants (G1 and G2) in APOL1 (apolipoprotein L1), encoding APOL1, and cardiovascular disease have been conflicting. We sought to explore associations of APOL1 risk variants with cause of sudden death using the CVPath Sudden Death Autopsy Registry. Approach and Results: APOL1 haplotypes and causes of sudden death, as determined through autopsy and histopathology, were obtained for 764 Black subjects. Genotyping revealed APOL1 risk alleles in 452 of 764 (59%) subjects with 347 (77%) subjects carrying one risk allele and 105 (23%) subjects harboring 2 risk alleles. APOL1 risk allele carrier status was associated with a significantly increased risk of coronary thrombosis due to plaque rupture, versus noncarriers (odds ratio for rupture, 1.655 [95% CI, 1.079–2.539]; P =0.021). Histological examinations showed coronary plaques in carriers of 2 APOL1 risk alleles had larger necrotic cores compared with noncarriers (necrotic core area/total plaque area: 46.79%±6.47% versus 20.57%±5.11%; P =0.0343 in ruptured plaques, and 41.48%±7.49% versus 18.93%±3.97%; P =0.0342 in nonruptured plaques), and immunohistochemical and immunofluorescent staining revealed APOL1-positive areas localized primarily to the necrotic core. Conclusions: APOL1 risk alleles were independently associated with an increased risk of thrombotic coronary death due to plaque rupture. Our results suggest that carriers of both 1 and 2 APOL1 risk alleles have greater accumulation of APOL1 protein within culprit plaques and greater necrotic core sizes than noncarriers. These findings suggest that APOL1 plays a role in determining plaque stability.

The three most common mechanisms of thrombosis in acute coronary syndrome (ACS) are plaque rupture, plaque erosion and calcified nodule. Plaque erosion occurs over an intact fibrous cap, commonly over pathological intimal thickening (PIT) rather than thin cap fibroatheroma (TCFA), and is more common among younger and female patients.1 A very rare mechanism of ACS is spontaneous coronary artery dissection (SCAD), resulting from the formation of an intramural hematoma and/or intimal disruption.2 We present a case of sudden coronary death with the appearance of SCAD on coronary computed tomography angiography (CCTA).

BACKGROUND: The relative thrombogenicity and albumin adsorption and retention of different durable polymers used in coronary stents has not been tested. AIMS: This study sought to compare the thromboresistance and albumin binding capacity of different durable polymer drug-eluting stents (DES) using dedicated preclinical and in vitro models. METHODS: In an ex vivo swine arteriovenous shunt model, a fluoropolymer everolimus-eluting stent (FP-EES) (n=14) was compared with two durable polymer DES, the BioLinx polymer-coated zotarolimus-eluting stent (BL-ZES) (n=9) and a CarboSil elastomer polymer-coated ridaforolimus-eluting stent (EP-RES) (n=6), and bare metal stents (BMS) (n=10). Stents underwent immunostaining using a cocktail of antiplatelet antibodies and a marker for inflammation and were then evaluated by confocal microscopy (CM). Albumin retention was assessed using a flow loop model with labelled human serum albumin (FP-EES [n=8], BL-ZES [n=4], EP-RES [n=4], and BMS [n=7]), and scanned by CM. RESULTS: The area of platelet adherence (normalised to total stent surface area) was lower in the order FP-EES (9.8%), BL-ZES (32.7%), EP-RES (87.6%) and BMS (202.0%), and inflammatory cell density was least for FP-EES

Objective: The role of glycolytic enzyme PKM2 (pyruvate kinase muscle 2) in smooth muscle cell (SMC) phenotype switching and neointimal hyperplasia is poorly understood. We determined the role of PKM2 in SMC phenotype switching and neointimal hyperplasia. Approach and Results: We show that PKM2 is expressed in the SMC-rich neointima of the murine carotid artery and peri-strut areas in bare-metal stented human coronary arteries. PDGF-BB (platelet-derived growth factor-BB) stimulation upregulates the expression of PKM2 in cultured murine and human coronary SMC. To provide conclusive evidence for PKM2 in SMC function, we generated SMC-specific PKM2 −/− mutant strain. We report that PKM2 deletion in SMC reduces injury-induced neointimal hyperplasia by inhibiting SMC proliferation and migration, suppressing synthetic phenotype, and reducing aerobic glycolysis associated with decreased ERK (extracellular signal-regulated kinase), mTOR (mammalian target of rapamycin), and STAT3 (signal transducer and activator of transcription 3) signaling. Furthermore, we show that nuclear PKM2 interacts with STAT3 and β-catenin and regulates transcription of MEK5 (mitogen/extracellular signal-regulated kinase kinase-5), cyclin D1, GLUT1 (glucose transporter 1), and LDHA (lactate dehydrogenase A). Treatment of human coronary SMC with ML265, an activator that induces PKM2 tetramerization and blocks its nuclear translocation, inhibited proliferation, migration, and phenotypic switching. Perivascular application of PKM2 activator reduced neointimal hyperplasia in mice. Conclusions: These findings reveal that PKM2 is a key regulator of SMC function in vascular remodeling and implicates PKM2 as a potential target to reduce neointimal hyperplasia.

Background Calcified nodule (CN) has a unique plaque morphology, in which an area of nodular calcification causes disruption of the fibrous cap with overlying luminal thrombus. CN is reported to be the least frequent cause of acute coronary thrombosis, and the pathogenesis of CN has not been well studied. Objectives The purpose of this study is to provide a comprehensive morphologic assessment of the CN in addition to providing an evolutionary perspective as to how CN causes acute coronary thrombosis in patients with acute coronary syndromes. Methods A total of 26 consecutive CN lesions from 25 subjects from our autopsy registry were evaluated. Detailed morphometric analysis was performed to understand the plaque characteristics of CN and nodular calcification. Results The mean age was 70 years, with a high prevalence of diabetes and chronic kidney disease. CNs were equally distributed between men and women, with 61.5% of CNs found in the right coronary artery (n = 16), mainly within its mid-portion (56%). All CNs demonstrated surface nonocclusive luminal thrombus, consisting of multiple nodular fragments of calcification, protruding and disrupting the overlying fibrous cap, with evidence of endothelial cell loss. The degree of circumferential sheet calcification was significantly less in the culprit section (89° [interquartile range: 54° to 177°]) than in the adjacent proximal (206° [interquartile range: 157° to 269°], p = 0.0034) and distal (240° [interquartile range: 178° to 333°], p = 0.0004) sections. Polarized picrosirius red staining showed the presence of necrotic core calcium at culprit sites of CNs, whereas collagen calcium was more prevalent at the proximal and distal regions of CNs. Conclusions Our study suggests that fibrous cap disruption in CN with overlying thrombosis is initiated through the fragmentation of necrotic core calcifications, which is flanked—proximally and distally—by hard, collagen-rich calcification in coronary arteries, which are susceptible to mechanical stress.

Objective: Persons with HIV have double the risk of developing cardiovascular disease compared with the general population. A persistent and heightened immune response to cytomegalovirus coinfection may be one contributing factor, but the relationship between cytomegalovirus replication, virus-specific immune cells, and plaque burden is unclear. Approach and Results: We assessed the relationship between CD4 + T-cell subsets and carotid plaque burden in a cohort of 70 HIV-positive participants with sustained viral suppression on a single antiretroviral regimen and without known cardiovascular disease. We evaluated relationships between immune parameters, carotid plaque burden, and brachial artery flow-mediated vasodilation using multivariable linear and logistic regression models. We found that participants with carotid plaque had increased circulating CX3CR1 + ~GPR56 + ~CD57 + (ie, C~G~C) + CD4 + T cells ( P =0.03), which is a marker combination associated with antiviral and cytotoxic responses. In addition, a median of 14.4% (IQR, 4.7%–32.7%) of the C~G~C + CD4 + T-cells expressed antigen receptors that recognized a single cytomegalovirus glycoprotein-B epitope. Using immunofluorescence staining, we found that CX3CR1 + CD4 + T cells were present in coronary plaque from deceased HIV-positive persons. C~G~C + CD4 + T cells were also present in cells isolated from the aorta of HIV-negative donors. Conclusions: HIV-positive persons with carotid atheroma have a higher proportion of circulating CD4 + T-cells expressing the C~G~C surface marker combination associated with antiviral and cytotoxic responses. These cells can be cytomegalovirus-specific and are also present in the aorta.

Background Short-term dual antiplatelet therapy (DAPT) is a suitable strategy after stent implantation especially in patients at high risk for bleeding. The thromboresistant characteristics and the healing profile permanent polymer stents such as the Resolute Onyx- drug-eluting stent (DES) has never been tested against the current approved stents for short-term DAPT, the polymer free (PF) biolimus-eluting stent (PF-BES) and bare metal stents (BMS) in dedicated preclinical models. Methods An ex-vivo porcine arteriovenous shunt and in-vivo flow loop model were used to evaluate thromboresistance. The healing profile was assessed in the rabbit model at 28 days by confocal microscopy (CM), scanning electron microscopy (SEM) and histology. Onyx-DES was separately compared with Onyx-BMS in first experiment and PF-BES in second experiment. Results In an ex-vivo shunt model, CM and SEM showed significantly less platelet adhesion for Onyx-DES relative to Onyx-BMS and PF-BES. In a flow loop model using human blood, platelet adhesion was also significantly less in Onyx-DES as compared to PF-BES and Onyx-BMS. In the healing study, Onyx-BMS showed significantly greater healing profile relative to Onyx-DES as expected, whereas Onyx-DES showed equivalent endothelial coverage by SEM and significantly less Evan's blue uptake and comparable colocalization of p120 and vascular endothelial-cadherin when compared with PF-BES. Conclusions Onyx-DES showed qualities of thomboresistance and healing which appear to be compatible with short-term DAPT. Thromboresistance was superior to PF-BES and healing was equivalent to PF-BES in this pre-clinical study. Onyx-DES might provide advantages when considering short-term DAPT especially in patients at high risk of bleeding.

Introduction: In-stent restenosis (ISR) has been one of the biggest limitations to the success of percutaneous coronary intervention for the treatment of coronary artery disease (CAD). The introduc...

To co-register conventional computed tomography angiography (CTA), with ex vivo micro-computed tomography (microCT) and histology of popliteal atherosclerotic plaques. Improving the non-invasive imaging capabilities may be valuable to advance patient care with peripheral arterial obstructive disease towards lesion and individual based treatment.In this prospective observational study, 12 popliteal arteries from 11 symptomatic patients who had undergone transfemoral amputations for chronic limb threatening ischaemia and who had pre-operative CTA, were analysed ex vivo by microCT and histology. A total of 353 histological cross sections were co-registered with microCT and CTA, and classified as: lipid rich (LP, n = 26), fibrous (FP, n = 80), or calcific (CP, n = 247) plaques. CTA and microCT plaque density was calculated in 791 regions of interest as Hounsfield units (HU).CTA and microCT could identify plaque components that were confirmed by histology such as fibrous tissue (FP), lipid pool/core (LP), and calcification (CP). MicroCT densities were 77.8 HU for FP (IQR 52.8, 129.5 HU), -28.4 HU for LP (IQR -87.1, 13.2 HU), and 3826.0 HU for CP (IQR 2989.0, 4501.0 HU). CTA densities of the three components of the plaque were: 78.0 HU for FP (IQR 59.5, 119.8 HU), 32.5 HU for LP (IQR 15.0, 42 HU), and 641.5 HU for CP (IQR 425.8, 1135 HU). The differences were statistically significant between the HU densitometric characteristics among the three groups (p .0001) for both imaging modalities. Overall, microCT performed better diagnostically than conventional CTA for the three types of plaques: areas under the receiving operator characteristics curve were greater for microCT than CTA for FP (0.97 vs. 0.90), for LP (0.88 vs. 0.67), and for CP (0.97 vs. 0.90).CTA and microCT can be used to identify histological atherosclerotic plaque components, with better diagnostic performance for microCT. This study demonstrates the feasibility of using microCT to assess plaque morphology lesions in a manner that approaches histology thus becoming a useful tool for ex vivo assessment of atherosclerosis and towards lesion based treatment.

Supplemental Digital Content is available in the text., Background: Rupture and erosion of advanced atherosclerotic lesions with a resultant myocardial infarction or stroke are the leading worldwide cause of death. However, we have a limited understanding of the identity, origin, and function of many cells that make up late-stage atherosclerotic lesions, as well as the mechanisms by which they control plaque stability. Methods: We conducted a comprehensive single-cell RNA sequencing of advanced human carotid endarterectomy samples and compared these with single-cell RNA sequencing from murine microdissected advanced atherosclerotic lesions with smooth muscle cell (SMC) and endothelial lineage tracing to survey all plaque cell types and rigorously determine their origin. We further used chromatin immunoprecipitation sequencing (ChIP-seq), bulk RNA sequencing, and an innovative dual lineage tracing mouse to understand the mechanism by which SMC phenotypic transitions affect lesion pathogenesis. Results: We provide evidence that SMC-specific Klf4- versus Oct4-knockout showed virtually opposite genomic signatures, and their putative target genes play an important role regulating SMC phenotypic changes. Single-cell RNA sequencing revealed remarkable similarity of transcriptomic clusters between mouse and human lesions and extensive plasticity of SMC- and endothelial cell-derived cells including 7 distinct clusters, most negative for traditional markers. In particular, SMC contributed to a Myh11-, Lgals3+ population with a chondrocyte-like gene signature that was markedly reduced with SMC-Klf4 knockout. We observed that SMCs that activate Lgals3 compose up to two thirds of all SMC in lesions. However, initial activation of Lgals3 in these cells does not represent conversion to a terminally differentiated state, but rather represents transition of these cells to a unique stem cell marker gene–positive, extracellular matrix-remodeling, “pioneer” cell phenotype that is the first to invest within lesions and subsequently gives rise to at least 3 other SMC phenotypes within advanced lesions, including Klf4-dependent osteogenic phenotypes likely to contribute to plaque calcification and plaque destabilization. Conclusions: Taken together, these results provide evidence that SMC-derived cells within advanced mouse and human atherosclerotic lesions exhibit far greater phenotypic plasticity than generally believed, with Klf4 regulating transition to multiple phenotypes including Lgals3+ osteogenic cells likely to be detrimental for late-stage atherosclerosis plaque pathogenesis.

Evaluation of coronary artery disease (CAD) using coronary computed tomography angiography (CCTA) has seen a paradigm shift in the last decade. Evidence increasingly supports the clinical utility of CCTA across various stages of CAD, from the detection of early subclinical disease to the assessment of acute chest pain. Additionally, CCTA can be used to noninvasively quantify plaque burden and identify high-risk plaque, aiding in diagnosis, prognosis, and treatment. This is especially important in the evaluation of CAD in immune-driven conditions with increased cardiovascular disease prevalence. Emerging applications of CCTA based on hemodynamic indices and plaque characterization may provide personalized risk assessment, affect disease detection, and further guide therapy. This review provides an update on the evidence, clinical applications, and emerging technologies surrounding CCTA as highlighted at the 2019 National Heart, Lung and Blood Institute CCTA Summit.

Supplemental Digital Content is available in the text.

Sudden death is the most abrupt clinical presentation of acute coronary syndrome. The presence of acute luminal thrombosis is the histopathological hallmark of sudden coronary death. There are 3 main etiologies that can give rise to an acute luminal thrombus: plaque rupture, plaque erosion and, less frequently, eruptive calcified nodules. Coronary computed tomography angiography (CCTA) has the ability to identify high-risk plaque features of coronary artery disease that are associated with future adverse cardiac events. In this report, we illustrate 2 cases of suspected sudden coronary death with a thorough description of how CCTA can be employed to detect high-risk plaque features using histopathology as a gold standard.

Objectives The objective of this study was to comprehensively evaluate the pathology of acute and chronic femoral stenting in symptomatic atherosclerotic patients and to understand the causes of stent failure (SF) using multimodality imaging including micro–computed tomography. Background Although the pathology of coronary stenting has been well studied, the pathology of lower extremity femoral stenting remains poorly understood. Methods Twelve stented femoral lesions removed at surgery (n = 10) and at autopsy (n = 2) were obtained from 10 patients (median age 74 years; interquartile range [IQR]: 66 to 82 years) with histories of peripheral artery disease (critical limb ischemia in 7) (7 men and 3 women). All specimens underwent radiography, micro–computed tomography, and histological assessment. Results The median duration of implantation was 150 days (IQR: 30 to 365 days), the median stent diameter was 5.90 mm (IQR: 5.44 to 7.16 mm), and the median stent length was 39.5 mm (IQR: 27 to 107.5 mm). Of the 12 stented lesions, 2 had drug-eluting stents, and 10 had bare-metal stents. SF was observed in 8 of 12 lesions. The major cause of SF was acute thrombosis (6 of 8), but causes varied (delayed healing, stent underexpansion, false lumen stenting, and fracture), and 2 had restenosis. Stent fractures were observed in 3 cases by micro–computed tomography. Both drug-eluting stents, implanted for >1 year, showed delayed healing with circumferential peristrut fibrin deposition and SF. Conclusions This histological study is the first to examine the pathological cause of SF. Stent thrombosis was the major cause of SF. Delayed healing was a common feature of bare-metal stents implanted for 1 year, showed delayed healing.

Supplemental Digital Content is available in the text., Objective: Atherosclerosis is the underlying cause of most cardiovascular disease, but mechanisms underlying atherosclerosis are incompletely understood. Ultrasound measurement of the carotid intima-media thickness (cIMT) can be used to measure vascular remodeling, which is indicative of atherosclerosis. Genome-wide association studies have identified many genetic loci associated with cIMT, but heterogeneity of measurements collected by many small cohorts have been a major limitation in these efforts. Here, we conducted genome-wide association analyses in UKB (UK Biobank; N=22 179), the largest single study with consistent cIMT measurements. Approach and Results: We used BOLT-LMM software to run linear regression of cIMT in UKB, adjusted for age, sex, and genotyping chip. In white British participants, we identified 5 novel loci associated with cIMT and replicated most previously reported loci. In the first sex-specific analyses of cIMT, we identified a locus on chromosome 5, associated with cIMT in women only and highlight VCAN as a good candidate gene at this locus. Genetic correlations with body mass index and glucometabolic traits were also observed. Two loci influenced risk of ischemic heart disease. ConclusionS: These findings replicate previously reported associations, highlight novel biology, and provide new directions for investigating the sex differences observed in cardiovascular disease presentation and progression.

Vascular and valvular calcification are commonly encountered in clinical medicine and a greater understanding of their significance and pathophysiology remain a subject of immense importance. In the coronary arteries, vascular calcification burden correlates with the severity of luminal stenosis and atherosclerotic plaque burden. While in progressive lesions, the presence of coronary calcification is not binary but rather depends on the type of calcification. Racial and gender differences, and comorbidities like diabetes mellitus and chronic kidney disease, all affect the presence and severity of calcification. The peripheral arteries of the lower extremities are affected by both medial calcification and intimal calcification, and the former barely contributes to luminal stenosis. The character of atherosclerosis differs between above-knee and below-knee lesions. Valvular calcification generally occurs on the aortic valve leaflets, and pathologic findings range from minimal fibrocalcific changes in early disease to end-stage lesions characterized by fibrotic thickening and nodular calcification. Valvular calcification is similar to atherosclerotic changes, in terms of lipid deposition, inflammation, osteogenic differentiation of valvular interstitial cells, and oxidative stress. However, the mechanisms of vascular and valvular calcification are still not well understood. A deeper understanding of vascular and valvular calcification is needed in order to develop effective anti-calcification therapies and to improve outcomes in these patients.

Histopathological studies have revealed key processes of atherosclerotic plaque thrombosis. However, the diversity and complexity of lesion types highlight the need for improved sub- phenotyping. We hypothesized that unbiased clustering of plaques based on gene expression results in an alternative categorization of late-stage atherosclerotic lesions.We analyzed the gene expression profiles of 654 advanced human carotid plaques. The unsupervised, transcriptome-driven clustering revealed five dominant plaque types. These novel plaque phenotypes associated with clinical presentation (pIn conclusion, the definition of the plaque at risk for a thrombotic event can be fine-tuned by in- depth transcriptomic based phenotyping. These differential plaque phenotypes prove clinically relevant for both carotid and coronary artery plaques and point to differential underlying biology of symptomatic lesions.

Background: The safety and efficacy of catheter-based radio frequency (RF) renal denervation (RDN) have been demonstrated in randomized, sham-controlled trials. Long-term durability of blood pressure reduction following RDN has also been demonstrated by all-comer registries, although published pre-clinical reports of functional renal nerve regrowth are not consistent. We quantified the processes that support RDN procedural durability utilizing animal models. Methods: Animal studies were conducted in accordance with published guidelines. RDN was performed (4 lesions in the main renal artery) in normotensive swine using the Symplicity Spyral™ RDN system (Medtronic, Santa Rosa, CA, USA). Two additional groups not undergoing RDN served as control. Serial histological tissue samples were obtained in separate groups at 7 (n=12/group) and 180 (N=16/group) days post-procedure in all animals followed by bioanalytical quantification of cortical norepinephrine (NE) levels and immunohistochemical analysis of renal cortical axon density in matched samples. Results: Renal cortical axon density and NE levels were significantly reduced at 7 days and persisted through 180 days following RDN compared with control ( Figure ). Nerve fibrosis and necrosis were observed in the region of ablation, while nerve body atrophy was apparent distal to ablation location at 180 days. Conclusions: Reductions in both NE and renal cortical axon density were sustained at 7 and 180 days post-RDN procedure using RF renal denervation in a normotensive swine model. These data confirm and extend other pre-clinical and clinical evidence of long-term durability of the RDN procedure using RF energy.

Radiation is associated with tissue damage and increased risk of atherosclerosis, but there are currently no treatments and a very limited mechanistic understanding of how radiation impacts tissue repair mechanisms. We uncovered that radiation significantly delayed temporal resolution programs that were associated with decreased efferocytosis in vivo. Resolvin D1 (RvD1), a known proresolving ligand, promoted swift resolution and restored efferocytosis in sublethally irradiated mice. Irradiated macrophages exhibited several features of senescence, including increased expression of p16INK4A and p21, heightened levels of SA-β-gal, COX-2, several proinflammatory cytokines/chemokines, and oxidative stress (OS) in vitro, and when transferred to mice, they exacerbated inflammation in vivo. Mechanistically, heightened OS in senescent macrophages led to impairment in their ability to carry out efficient efferocytosis, and treatment with RvD1 reduced OS and improved efferocytosis. Sublethally irradiated Ldlr−/− mice exhibited increased plaque necrosis, p16INK4A cells, and decreased lesional collagen compared with nonirradiated controls, and treatment with RvD1 significantly reduced necrosis and increased lesional collagen. Removal of p16INK4A hematopoietic cells during advanced atherosclerosis with p16-3MR mice reduced plaque necrosis and increased production of key intraplaque-resolving mediators. Our results demonstrate that sublethal radiation drives macrophage senescence and efferocytosis defects and suggest that RvD1 may be a new therapeutic strategy to limit radiation-induced tissue damage.

Background: The aim of this pilot clinical study is to evaluate the safety and efficacy of the Selution Sustained Limus Release (SLR)™ sirolimus-coated balloon (M.A. MedAlliance SA, Nyon, Switzerland) for improving the patency of failing arterio-venous fistulas (AVF) in hemodialysis patients. We also present herein a pre-clinical pharmacokinetic and safety evaluation of Selution™ to justify its first use in hemodialysis patients for endovascular access salvage. Methods and results: This is an investigator-initiated prospective single-center, non-blinded single-arm trial. Forty patients with clinically significant de novo or recurrent stenoses in a mature AVF circuit will be recruited. All stenotic lesions will be prepared with high pressure non-compliant conventional balloon angioplasty (CBA) prior to deployment of the Sustained-Release Selution™ sirolimus drug-eluting balloon. The primary efficacy endpoint is 6-month target lesion primary patency and the primary safety endpoint is freedom from localized or systemic serious adverse events through 30 days. Secondary endpoints of interest include technical and clinical success rates and circuit access patency at 3 and 6 months. Follow-up will occur for 2 years for those patients whose AVFs remain patent. Pharmacokinetic and histological animal safety studies performed with the Selution™ coating formulation showed prolonged arterial tissue retention of sirolimus with therapeutic levels up to 60 days and non-toxic and rapidly declining blood levels. Histological results in animal models demonstrated safety, freedom from intraluminal thrombus, reduction in restenosis by sirolimus elution compared to CBA, and no evidence of embolic phenomena indicative of adverse particulate effects. Discussion: Long release sirolimus coated balloons may serve as a promising novel alternative therapy to paclitaxel-based technology for treating conduit stenosis secondary to neointimal hyperplasia. Pre-clinical pharmacokinetic and histological animal data are encouraging and provide suggestion of safety and efficacy in this setting. This single-center trial will provide a first step toward demonstration of efficacy and safety of this device for treatment of stenotic fistulas.

Objective: Healing processes, particularly reendothelialization, are essential for vascular homeostasis after plain old balloon angioplasty and stent implantation. Drug-eluting stents (DES) are commonly used for percutaneous coronary intervention because restenosis rates are reduced as compared with bare metal stents (BMS). However, in addition to understanding the nature of regenerated endothelial cells, concerns over incomplete stent healing persist, and the molecular effects of antiproliferative drug coatings on endothelium remain poorly understood. Approach and Results: We used the rabbit iliac artery model to analyze differences in stent endothelialization in BMS and DES. Histology and immunohistochemistry confirmed that stent coverage was significantly greater in BMS than in DES at 30 days after stent implantation. Single-cell RNA sequencing revealed a more immature transcriptomic signature of neointimal endothelial cell harvested from stented arteries in comparison with native and plain old balloon angioplasty–treated arteries. Whereas the genetic signature of BMS was overall proangiogenic with enrichment of genes involved in endothelial proliferation, sprouting, and migration, as well as extracellular matrix assembly, DES-derived endothelial cell showed upregulation of genes associated with angiogenesis inhibition and endothelial activation. Conclusions: Single-cell RNA sequencing analysis identified unique transcriptional changes within regenerated endothelium after plain old balloon angioplasty and stent implantation. These data suggest unique endothelial transcriptional differences, which characterize the different response of the endothelium to vascular injury and may help explain why long-term responses in DES remain suboptimal.

Radiation is associated with tissue damage and increased risk of atherosclerosis but there are currently no treatments and a very limited mechanistic understanding of how radiation impacts tissue repair mechanisms. We uncovered that radiation significantly delayed temporal resolution programs that was associated with decreased efferocytosis in vivo. Resolvin D1 (RvD1), a known pro-resolving ligand, promoted swift resolution and restored efferocytosis in sub-lethally irradiated mice. Irradiated macrophages exhibited several features of senescence, including increased expression of p16INK4A and p21, heightened levels of SA-β-gal, COX-2, and oxidative stress (OS) in vitro, and when transferred to mice exacerbated inflammation in vivo. Mechanistically, heightened OS in senescent macrophages led to impairment in their ability to carry out efficient efferocytosis and treatment with RvD1 reduced OS and improved efferocytosis. Sub-lethally irradiated Ldlr-/- mice exhibited increased plaque necrosis and p16INK4A cells compared with non-irradiated controls and treatment with RvD1 significantly reduced these endpoints. Removal of p16INK4A hematopoietic cells during advanced atherosclerosis with p16-3MR mice reduced plaque necrosis and increased production of key intraplaque resolving mediators. Our results demonstrate that sub-lethal radiation drives macrophage senescence and efferocytosis defects and suggest that RvD1 may be a new therapeutic strategy to limit radiation-induced tissue damage.

Drug-coated balloons (DCBs) have become an established therapy for the treatment of above-the-knee peripheral artery disease. The paclitaxel DCB has shown clinical benefit in terms of patency and freedom from re-intervention in multiple randomised trials. However, a recent meta-analysis has suggested an association between mortality and the use of paclitaxel-coated devices. Sirolimus is another potential choice of anti-proliferative agent for use in DCBs because of its wider therapeutic index and lower risk for dose-dependent toxicity. More recently, encapsulating sirolimus in micro-reservoirs or polymers has facilitated the development of effective sirolimus DCBs, some of which are available in Europe and Asia. In this review, the authors focus on paclitaxel and sirolimus DCB technologies from the standpoint of drug characteristics and clinical trials.

Iron is fundamental for life-essential processes. However, it can also cause oxidative damage, which is thought to trigger numerous pathologies, including cardiovascular diseases. The role of iron in the pathogenesis of atherosclerosis is still not completely understood. Macrophages are both key players in the handling of iron throughout the body and in the onset, progression and destabilization of atherosclerotic plaques. Iron itself might impact atherosclerosis through its effects on macrophages. However, while targeting iron metabolism within macrophages may have some beneficial effects on preventing atherosclerotic plaque progression there may also be negative consequences. Thus, the prevailing view of iron being capable of accelerating the progression of coronary disease through lipid peroxidation may not fully take into account the multi-faceted role of iron in pathogenesis of atherosclerosis. In this review, we will summarize the current understanding of iron metabolism in the context of the complex interplay between iron, inflammation, and atherosclerosis. Keywords: Iron metabolism, Hepcidin-ferroportin axis, Atherosclerosis, Intraplaque haemorrhage, Macrophages

Objectives The aim of this study was to comprehensively evaluate the pathology of the lower extremity arteries across their entire length in subjects dying with abundant risk factors and to evaluate the clinical and imaging implications of the pathological characteristics. Background Lower extremity peripheral arterial disease is a major cause of cardiovascular morbidity, but a systematic characterization of the pathology has never been undertaken. Methods Twelve legs were obtained from 8 cadavers with histories of coronary risk factors (median age 82 years, 6 men); 8 of 12 legs were evaluated using computed tomography before the major peripheral arteries were dissected along their entire length. Dissected arteries were cut serially at 3 to 4 mm, and a total of 2,987 sections were examined. Results Luminal irregularities and stenosis were more commonly seen in computed tomography images of above-the-knee (AK) arteries. Atherosclerotic lesions were histologically confirmed and were more common in AK (95.7%) than below-the-knee (BK) (56.8%) arteries. Occluded vessels were observed at 18 sites, including 8 AK and 10 BK arteries. Pathologically, acute thrombus was observed in all 8 AK sites, of which 3 were associated with plaque rupture and 5 were related to calcified nodules. The 10 occluded BK arteries revealed chronic total occlusions, of which one-half were embolic in origin and one-half were associated with atherosclerotic lesions. Intimal (75.3%) and medial (86.2%) calcifications were commonly encountered. Proportionate to the neointimal atherosclerosis, intimal calcification was more severe in AK arteries; the severity of medial calcification was no different between AK and BK arteries. Calcification was significantly greater in arteries excised from subjects with compared with those without diabetes. Conclusions Atherosclerosis occurs more commonly in AK arteries and luminal occlusion from acute thrombosis secondary to rupture or calcified nodules. BK occlusion was chronic in nature, and at least one-half of lesions were embolic in origin. Medial calcification was similarly common in AK and BK arteries but more prevalent in subjects with diabetes.

Implantation of drug-eluting stents (DES) is the dominant treatment strategy for patients with symptomatic coronary artery disease. However, the first-generation DES had substantial drawbacks, including delayed healing, local hypersensitivity reactions and neoatherosclerosis, which all led to a steady increase in major adverse cardiovascular events over time. Subsequently, newer-generation DES were introduced with thinner struts, different scaffold designs (to improve deliverability while maintaining radial strength), different durable and biodegradable polymers - and in some cases no polymer (to improve vascular biocompatibility) - and new antiproliferative drug types and doses. Currently, >30 different DES are commercially available in Europe, with fewer available in the USA but with many new entrants coming onto the US market in the next few years. Never before have cardiologists been faced with so many choices of stent, each with its own unique design. In this Review, we detail preclinical and pathology studies for each stent design, examining thromboresistance, speed of neointimal coverage and completeness of healing, including endothelialization. We conclude by discussing how these design characteristics might affect the potential for shortening the minimum duration of dual antiplatelet therapy needed after coronary intervention.

Endovascular therapy has evolved as a main treatment option especially in patients with short (

Purpose To investigate morphometric characteristics and differences in particulate embolization between 3 drug-coated balloons (DCBs). Materials and Methods Effects of 3 overlapping DCBs (IN.PACT, Ranger, and Stellarex) were assessed in 24 femoral arteries of 12 swine with 28-day follow-up. Histologic analysis of treated arterial wall site and downstream skeletal muscle and coronary band changes were assessed for evidence of emboli. Paclitaxel concentration for downstream skeletal muscle and coronary band and vessel diameters with downstream changes were also measured. Results Signs of drug effect, such as medial smooth muscle cell (SMC) loss in depth and circumference, were not significantly different for all 3 DCBs (IN.PACT vs Ranger vs Stellarex: SMC loss depth, 2.8 [interquartile range [IQR]: 2.1–3.6] vs 3.2 [IQR: 2.3–3.8] vs 3.5 [IQR: 2.6–3.8], P = .7; SMC loss circumference, 1.0 [IQR: 1.0–1.0] vs 1.3 [IQR: 1.0–1.8] vs 1.0 [IQR: 1.0–1.2], P = .08). Percentage of sections with vascular changes in downstream nontarget tissues from arteries was similar in all 3 DCBs (42.9% vs 25.0% vs 28.6%, P = .2). Downstream levels of paclitaxel concentration in skeletal muscle were significantly higher for IN.PACT (216.5 ng/g vs 91.5 ng/g vs 101.9 ng/g, P = .01). Median vessel diameters with evidence of downstream changes were smallest for IN.PACT compared with Ranger and Stellarex (57 μm vs 74 μm vs 64 μm). Conclusions All 3 DCBs exhibited no significant difference in local target site drug effect based on histologic analysis. Downstream effects of paclitaxel and/or downstream emboli were highest for IN.PACT compared with Ranger and Stellarex, whereas vessel diameters with evidence of downstream changes were smaller for IN.PACT vs Ranger and Stellarex.

Background Recent clinical studies have suggested the feasibility of 1-month dual antiplatelet therapy (DAPT) for patients receiving drug-eluting stent (DES). Although our previous ex-vivo swine arteriovenous (AV) shunt studies under low dose heparin treatment suggested superior thromboresistance of fluoropolymer-coated everolimus-eluting stent (FP-EES) when compared to other polymer-based DESs, the relative thromboresistance of different DESs under single antiplatelet therapy (SAPT) has never been examined. This study aimed to evaluate platelet adhesion under SAPT in competitive DESs in the in vitro flow loop model and ex vivo swine AV shunt model. Methods The thrombogenicity of FP-EES, BioLinx polymer zotarolimus-eluting stent (BL-ZES), and biodegradable polymer everolimus-eluting stent (BP-EES) was assessed acutely using the swine AV shunt model under aspirin or clopidogrel SAPT. Stents were immunostained using antibodies against platelets and inflammatory markers and evaluated by confocal microscopy. Also, the adhesion of platelet and albumin on the three DESs was assessed by an in-vitro flow loop model using human platelets under aspirin SAPT and fluorescent albumin, respectively. Results In the shunt model, FP-EES showed significantly less platelet and inflammatory cell adhesion than BL-ZES and BP-EES. In the flow loop model, FP-EES showed significantly less platelet coverage and more albumin adsorption than BL-ZES and BP-EES. Conclusions These results suggest FP-EES may have particular advantage for short-term DAPT compared to other DESs.

Background Cytokine storm-related hypercoagulation may be important in the pathogenesis of stent thrombosis in patients with SARS-CoV-2. Whether stent polymers behave differently under such conditions has never been explored. Methods Fluorinated polymer-nanocoated and uncoated COBRA stents (CeloNova), BioLinx-polymer-coated Resolute Onyx stents (Medtronic), and Synergy stents (Boston Scientific), which are abluminally coated with a bioabsorbable polymer, were exposed to human blood from healthy donors which was supplemented with 400 pg/mL IL-6 and 100 pg/mL TNF-α, similar to what is seen in cytokine storm caused by SARS-CoV-2. Platelet adhesion and neutrophil activation, assessed by immunofluorescence, were compared under cytokine storm and control conditions (untreated blood) (n = 4 experimental runs). Results Platelet adhesion values, defined as %platelet-covered area x staining intensity, were significantly lower in coated and uncoated COBRA and in Resolute Onyx than in Synergy under control conditions (1.28 × 107 ± 0.43 × 107 vs. 2.92 × 107 ± 0.49 × 107 vs. 3.57 × 107 ± 0.73 × 107 vs. 9.94 × 107 ± 0.99 × 107; p ≤0.0001). In cytokine storm, platelet adhesion values remained low in coated COBRA-PzF (1.78 × 107 ± 0.38 × 107) compared to all other devices (uncoated COBRA: 5.92 × 107 ± 0.96 × 107; Resolute Onyx: 7.27 × 107 ± 1.82 × 107; Synergy: 11.28 × 107 ± 1.08 × 107; p ≤0.0001). Although cytokine storm conditions significantly increased neutrophil activation in all stents, it was significantly less in coated and uncoated COBRA, and in Resolute Onyx than in Synergy. Conclusions Blood-biomaterials interactions may determine the thrombogenic potential of stents. Under simulated cytokine storm conditions, fluoropolymer-coated stents showed the most favorable anti-thrombogenic and anti-inflammatory properties., Graphic abstract Severe COVID-19 infection is associated with overproduction of cytokines by macrophages, activated T-cells, and neutrophils. Especially IL-6 and TNF-α trigger hypercoagulation, potentially playing a role in the pathogenesis of MI. PCI in this situation holds an increased risk of ST. Under in vitro simulated cytokine storm conditions, stents with fluoropolymer coatings had less platelet adhesion and neutrophil activation than uncoated and BioLinx polymer-coated stents and compared with stents abluminally coated with bioabsorbable polymers.Unlabelled Image

Background: Cardiac injury is common in patients who are hospitalized with coronavirus disease 2019 (COVID-19) and portends poorer prognosis. However, the mechanism and the type of myocardial damage associated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) remain uncertain. Methods: We conducted a systematic pathological analysis of 40 hearts from hospitalized patients dying of COVID-19 in Bergamo, Italy, to determine the pathological mechanisms of cardiac injury. We divided the hearts according to presence or absence of acute myocyte necrosis and then determined the underlying mechanisms of cardiac injury. Results: Of the 40 hearts examined, 14 (35%) had evidence of myocyte necrosis, predominantly of the left ventricle. Compared with subjects without necrosis, subjects with necrosis tended to be female, have chronic kidney disease, and have shorter symptom onset to admission. The incidence of severe coronary artery disease (ie, >75% cross-sectional narrowing) was not significantly different between those with and without necrosis. Three of 14 (21.4%) subjects with myocyte necrosis showed evidence of acute myocardial infarction, defined as ≥1 cm 2 area of necrosis, whereas 11 of 14 (78.6%) showed evidence of focal (>20 necrotic myocytes with an area of ≥0.05 mm 2 but 2 ) myocyte necrosis. Cardiac thrombi were present in 11 of 14 (78.6%) cases with necrosis, with 2 of 14 (14.2%) having epicardial coronary artery thrombi, whereas 9 of 14 (64.3%) had microthrombi in myocardial capillaries, arterioles, and small muscular arteries. We compared cardiac microthrombi from COVID-19–positive autopsy cases to intramyocardial thromboemboli from COVID-19 cases as well as to aspirated thrombi obtained during primary percutaneous coronary intervention from uninfected and COVID-19–infected patients presenting with ST-segment–elevation myocardial infarction. Microthrombi had significantly greater fibrin and terminal complement C5b-9 immunostaining compared with intramyocardial thromboemboli from COVID-19–negative subjects and with aspirated thrombi. There were no significant differences between the constituents of thrombi aspirated from COVID-19–positive and –negative patients with ST-segment–elevation myocardial infarction. Conclusions: The most common pathological cause of myocyte necrosis was microthrombi. Microthrombi were different in composition from intramyocardial thromboemboli from COVID-19–negative subjects and from coronary thrombi retrieved from COVID-19–positive and –negative patients with ST-segment–elevation myocardial infarction. Tailored antithrombotic strategies may be useful to counteract the cardiac effects of COVID-19 infection.

Primary percutaneous coronary intervention (PPCI) has dramatically changed the outcome of patients with ST-elevation myocardial infarction (STEMI). However, despite improvements in interventional technology, registry data show little recent change in the prognosis of patients who survive STEMI, with a significant incidence of cardiogenic shock, heart failure, and cardiac death. Despite a technically successful PPCI procedure, a variable proportion of patients experience suboptimal myocardial reperfusion. Large infarct size and coronary microvascular injury, as the consequence of ischaemia–reperfusion injury and distal embolization of atherothrombotic debris, account for suboptimal long-term prognosis of STEMI patients. In order to address this unmet therapeutic need, a broad-range of device-based treatments has been developed. These device-based therapies can be categorized according to the pathophysiological pathways they target: (i) techniques to prevent distal atherothrombotic embolization, (ii) techniques to prevent or mitigate ischaemia/reperfusion injury, and (iii) techniques to enhance coronary microvascular function/integrity. This review is an overview of these novel technologies with a focus on their pathophysiological background, procedural details, available evidence, and with a critical perspective about their potential future implementation in the clinical care of STEMI patients.

COVID-19 infection appeared to be associated with increased risk of thrombotic events, ranging from microvascular thrombosis to venous thromboembolic disease (including deep vein thrombosis and pulmonary embolism), and stroke [1].