Ioannis Drosos

Background: Percutaneous left atrial appendage occlusion (LAAO) represents an alternative stroke prevention method in patients with atrial fibrillation and an increased bleeding risk, chronic kidney disease or contraindications to oral anticoagulants. Aim of our study was to evaluate the feasibility and safety of percutaneous LAAO in high-risk, frail patients having undergone transcatheter aortic valve implantation (TAVI). Methods: Thirty-one patients having undergone TAVI and scheduled for LAAO were prospectively included in our study. Results: Implantation was successful in 29 of 31 cases (93.5%).There were no patients that developed a major acute cardiovascular event, stroke, or device dislocation/embolization. There was a single case of major bleeding (3.2%) and 3 cases of acute kidney injury (9.7%). At 3 months, no patients experienced a stroke, one patient had a device-related thrombus (3.4%), one patient showed a significant peri-device leak, and one patient had a persistent iatrogenic atrial septal defect. Conclusions: Our study shows that percutaneous LAAO may represent a feasible alternative strategy for stroke prevention, that can be safely performed in high-risk, multimorbid patients with high bleeding risk or contraindications to oral anticoagulation.

Cardiovascular risk factors may act by modulating the composition and function of the adventitia. Here we examine how age affects perivascular adipose tissue (PVAT) and its paracrine activities during neointima formation. Aortic tissue and PVAT or primary aortic smooth muscle cells from male C57BL/6JRj mice aged 52 weeks (“middle-aged”) were compared to tissue or cells from mice aged 16 weeks (“adult”). Vascular injury was induced at the carotid artery using 10% ferric chloride. Carotid arteries from the middle-aged mice exhibited smooth muscle de-differentiation and elevated senescence marker expression, and vascular injury further aggravated media and adventitia thickening. Perivascular transplantation of PVAT had no effect on these parameters, but age-independently reduced neointima formation and lumen stenosis. Quantitative PCR analysis revealed a blunted increase in senescence-associated proinflammatory changes in perivascular tissue compared to visceral adipose tissue and higher expression of mediators attenuating neointima formation. Elevated levels of protein inhibitor of activated STAT1 (PIAS1) and lower expression of STAT1- or NFκB-regulated genes involved in adipocyte differentiation, inflammation, and apoptosis/senescence were present in mouse PVAT, whereas PIAS1 was reduced in the PVAT of patients with atherosclerotic vessel disease. Our findings suggest that age affects adipose tissue and its paracrine vascular activities in a depot-specific manner. PIAS1 may mediate the age-independent vasculoprotective effects of perivascular fat.

Experimental and human autopsy studies have associated adventitial lymphangiogenesis with atherosclerosis. An analysis of perivascular lymphangiogenesis in patients with coronary artery disease is lacking. Here, we examined lymphangiogenesis and its potential regulators in perivascular adipose tissue (PVAT) surrounding the heart (C-PVAT) and compared it with PVAT of the internal mammary artery (IMA-PVAT). Forty-six patients undergoing coronary artery bypass graft surgery were included. Perioperatively collected C-PVAT and IMA-PVAT were analyzed using histology, immunohistochemistry, real time PCR, and PVAT-conditioned medium using cytokine arrays. C-PVAT exhibited increased PECAM-1 (platelet endothelial cell adhesion molecule 1)-positive vessel density. The number of lymphatic vessels expressing lymphatic vessel endothelial hyaluronan receptor-1 or podoplanin was also elevated in C-PVAT and associated with higher inflammatory cell numbers, increased intercellular adhesion molecule 1 (ICAM1) expression, and fibrosis. Significantly higher expression of regulators of lymphangiogenesis such as vascular endothelial growth factor (VEGF)-C, VEGF-D, and VEGF receptor-3 was observed in C-PVAT compared to IMA-PVAT. Cytokine arrays identified angiopoietin-2 as more highly expressed in C-PVAT vs. IMA-PVAT. Findings were confirmed histologically and at the mRNA level. Stimulation of human lymphatic endothelial cells with recombinant angiopoietin-2 in combination with VEGF-C enhanced sprout formation. Our study shows that PVAT surrounding atherosclerotic arteries exhibits more extensive lymphangiogenesis, inflammation, and fibrosis compared to PVAT surrounding a non-diseased vessel, possibly due to local angiopoietin-2, VEGF-C, and VEGF-D overexpression.

Background: Intraplaque hemorrhage promotes atherosclerosis progression, and erythrocytes may contribute to this process. In this study we examined the effects of red blood cells on smooth muscle cell mineralization and vascular calcification and the possible mechanisms involved. Methods: Erythrocytes were isolated from human and murine whole blood. Intact and lysed erythrocytes and their membrane fraction or specific erythrocyte components were examined in vitro using diverse calcification assays, ex vivo by using the murine aortic ring calcification model, and in vivo after murine erythrocyte membrane injection into neointimal lesions of hypercholesterolemic apolipoprotein E–deficient mice. Vascular tissues (aortic valves, atherosclerotic carotid artery specimens, abdominal aortic aneurysms) were obtained from patients undergoing surgery. Results: The membrane fraction of lysed, but not intact human erythrocytes promoted mineralization of human arterial smooth muscle cells in culture, as shown by Alizarin red and van Kossa stain and increased alkaline phosphatase activity, and by increased expression of osteoblast-specific transcription factors (eg, runt-related transcription factor 2, osterix) and differentiation markers (eg, osteopontin, osteocalcin, and osterix). Erythrocyte membranes dose-dependently enhanced calcification in murine aortic rings, and extravasated CD235a-positive erythrocytes or Perl iron-positive signals colocalized with calcified areas or osteoblast-like cells in human vascular lesions. Mechanistically, the osteoinductive activity of lysed erythrocytes was localized to their membrane fraction, did not involve membrane lipids, heme, or iron, and was enhanced after removal of the nitric oxide (NO) scavenger hemoglobin. Lysed erythrocyte membranes enhanced calcification to a similar extent as the NO donor diethylenetriamine-NO, and their osteoinductive effects could be further augmented by arginase-1 inhibition (indirectly increasing NO bioavailability). However, the osteoinductive effects of erythrocyte membranes were reduced in human arterial smooth muscle cells treated with the NO scavenger 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide or following inhibition of NO synthase or the NO receptor soluble guanylate cyclase. Erythrocytes isolated from endothelial NO synthase–deficient mice exhibited a reduced potency to promote calcification in the aortic ring assay and after injection into murine vascular lesions. Conclusions: Our findings in cells, genetically modified mice, and human vascular specimens suggest that intraplaque hemorrhage with erythrocyte extravasation and lysis promotes osteoblastic differentiation of smooth muscle cells and vascular lesion calcification, and also support a role for erythrocyte-derived NO.

Background: With this study, we sought to investigate the prognostic value of echocardiographic tissue imaging markers in predicting tamponade among patients with large malignant pericardial effusion compared to routinely used echocardiographic signs.Methods: A total of 96 consecutive patients with large malignant pericardial effusion, not in clinical cardiac tamponade, underwent an echocardiographic examination and were prospectively assessed for 1 month. Clinically evident cardiac tamponade was considered as the study endpoint. The prognostic performance of tricuspid valve annular plane systolic excursion (TAPSE) and peak systolic annular velocity at the lateral margin of the tricuspid valve annulus (S_TV) was assessed and compared to routinely used imaging signs.Results: During follow‐up, 37 patients (39%) developed clinically evident cardiac tamponade. TAPSE (area under the curve [AUC] 0.958) and S_TV (AUC 0.948) had excellent predictive accuracy for tamponade. Multivariate analysis showed that TAPSE (Hazard ratio [HR] 3.03; 95% CI 1.60–5.73, P=.001) and S_TV (HR 1.17; 95% CI 1.05–1.29, P=.005) remained independent significant predictors of cardiac tamponade. Reclassification analysis and decision curve analysis showed additive prognostic value and adjunct clinical benefit of these markers when added to a recently published triage pericardiocentesis score.Conclusion: Echocardiographic tissue imaging markers such as TAPSE and S_TV are characterized by an excellent prognostic ability for development of cardiac tamponade and better prognostic value compared to routine echocardiographic signs in patients with large malignant pericardial effusion. Incorporating these markers to a recent triage pericardiocentesis score resulted in additional prognostic value and increased clinical benefit.

Obesity is associated with an increased cardiovascular risk, but the mechanisms underlying the link between increased body weight and vascular disease are incompletely understood. Over the past 15 years, perivascular adipose tissue has emerged as active component of the vessel wall involved in vascular homeostasis. However, perivascular adipose tissue can adopt detrimental properties under the influence of obesity and other factors and contribute actively to the pathophysiology of cardiovascular disease. Conversely, changes of the vessel wall may negatively affect perivascular adipose tissue qualities. In this review, we will discuss the recent literature on the possible direct and indirect connections between perivascular fat alterations and cardiovascular pathologies. In addition to clinical evidence on the association between perivascular fat mass and morphology and anthropometric measures of obesity or the reciprocal connection between perivascular fat and cardiometabolic risk factors and disease, special emphasis will be placed on results in rodent and other models and the possible direct contribution of local fat depots to vascular dysfunction, neointima formation or atherosclerosis. We will briefly highlight results from human and murine genome, miRNome and proteome-wide expression analyses of potential candidate mediators involved in its paracrine activities and present data on how the cardiovascular risk factors obesity, age or diabetes, but also the preventive measures weight loss or exercise impact on perivascular expression patterns. A better understanding of this unique adipose tissue depot, its properties and regulatory mechanisms, may create opportunities for novel diagnostic and therapeutic strategies to combat the cardiovascular consequences of increased body weight.

Contrast-induced acute kidney injury (CI-AKI) is a common complication of intravascular administration of contrast media used in coronary angiography, percutaneous coronary intervention and other diagnostic and interventional procedures. This review article aims at summarizing the published literature regarding the prevention of CI-AKI, by focusing on available high-quality meta-analyses addressing this matter. Apart from adequate hydration, a number of pharmacologic agents have been proposed as potential candidates to be included in the routine preparation, prior to the patient’s arrival in the cardiac catheterization laboratory. Among them, statins and N-acetylcysteine appear to be the most extensively studied ones. Throughout this article we present the available data on CI-AKI prevention and provide a critical clinical appraisal, as well as a summary of currently available guidelines.

Aim The factors mediating the paracrine effects of perivascular adipose tissue (PVAT) in atherosclerosis are largely unknown. The adipokine leptin has been implicated in the increased cardiovascular risk in obesity and may locally promote neointima formation independently of circulating leptin levels. In patients with established coronary artery disease, we examined the expression of leptin as well as of its possible inducers in ‘cardiac’ PVAT surrounding the aortic root and coronary arteries (C-PVAT), and compared it to the PVAT surrounding the internal mammary artery (IMA-PVAT), a vessel resistant to atherosclerosis. Methods and results Tissue specimens collected from male patients undergoing coronary artery bypass surgery were processed for real-time PCR, ELISA, in situ hybridization, and immunohistochemistry analysis. Leptin protein expression was elevated in C-PVAT compared to IMA-PVAT, independent of serum leptin levels. Compared to IMA-PVAT, C-PVAT exhibited more pronounced angiogenesis and inflammation, as indicated by significantly higher numbers of PECAM1-positive vessels and CD68-positive macrophages, and was characterized by a greater extent of fibrosis and hypoxia. Increased expression of hypoxia-inducible factor-1α and Fos-like antigen (FOSL)2, factors known to enhance leptin gene transcription, was observed in C-PVAT. As a proof of concept, exposure of human adipocytes to chemical hypoxia resulted in significantly increased FOSL2 and leptin mRNA levels. Conclusions A higher degree of local tissue hypoxia and up-regulation of leptin expression in the perivascular adipose tissue, along with increased vascularization, inflammation, and fibrosis, may contribute to the increased atherosclerotic plaque burden in the coronary arteries compared to the IMA.

Contrast-induced acute kidney injury (CI-AKI) is defined as an abrupt deterioration in renal function associated with the administration of iodinated contrast media. This type of acute kidney injury is frequently encountered as a complication of percutaneous coronary intervention (PCI) and is associated with adverse short- and long-term outcomes including mainly mortality, cardiovascular morbidity and prolongation of hospitalization. The incidence of CI-AKI after PCI ranges from 2 to 20 % according to baseline kidney function. It may also range according to the clinical setting, being higher after emergency PCI. The primary manifestation is a small decline in kidney function, occurring 1 to 3 days after the procedure. Kidney function usually returns to preexisting levels within 7 days. Incidence of acute renal failure requiring dialysis following PCI is rare (<1 %). The present article aims to review up-to-date published data concerning diagnosis, definition, epidemiology and prognosis of this novel in-hospital epidemic.