Determinants and treatments of heart failure after transcatheter aortic valve implantation: moving up a notch

Transcatheter aortic valve implantation (TAVI) has become an alternative to surgical aortic valve replacement for patients with symptomatic severe aortic stenosis in elderly and comorbid population. Significant improvement in heart function has been observed in patients undergoing TAVI, but numerous patients are readmitted to hospital for heart failure (HF). Moreover, repeat HF hospitalization is strongly associated with an adverse prognosis and increases the financial burden of health care. Although studies have identified pre-existing and post-procedural factors that contribute to HF hospitalization after TAVI, there is a paucity of data regarding optimal post-procedural pharmacological treatments. This review aims to provide an overview of the current understanding of mechanisms, determinants, and potential treatments of HF following TAVI. We first review the pathophysiology of left ventricular (LV) remodelling, coronary microcirculation disorder, and endothelial dysfunction in patients with aortic stenosis and then examine the impact of TAVI on these conditions. We then present evidence of various factors and complications that may interplay with LV remodelling and contribute to HF events after TAVI. Next, we describe the triggers and predictors of early and late HF rehospitalizations following TAVI. Lastly, we discuss the potential of conventional pharmacological treatments, including renin-angiotensin blockers, beta-blockers, and diuretics in TAVI patients. The paper explores the potential of newer drugs, including sodium-glucose co-transporter 2 inhibitors, anti-inflammatory drugs, and ion supplementation. Comprehensive knowledge in this field may aid in recognizing successful existing therapies, developing effective new treatments, and establishing dedicated patient care strategies during follow-up after TAVI.

Aortic stenosis and the hemostatic system

Aortic stenosis (AS) affects more than 10% of the population over 80 years of age and constitutes a major risk factor for heart failure, thromboembolic stroke, and death. A better understanding of the disease, including its interaction with the hemostatic system, is a prerequisite to develop prophylactic treatments. AS pathogenesis is a dynamic process involving endothelial dysfunction, inflammation, fibrosis, and calcification. Several studies support the interplay between the components of the hemostatic system such as platelets, the coagulation system, von Willebrand factor, and extracellular microparticles at each pathophysiological stage of AS. Previous reports have evidenced persistent biological activity of the native valve after transcatheter aortic valve replacement (TAVR) and the subsequent development of microthrombosis that may impact the function of the newly implanted valve. Here, we review the current evidence on the interplay between AS and prothrombotic activity, and we emphasize the clinical consequences of these interactions after aortic valve replacement.

Enrichment in procoagulant microparticles in calcified human aortic valve – role in valvular endothelium alterations and enhanced thrombogenicity

Background

Aortic stenosis (AS) is characterized by endothelial dysfunction (ED), inflammatory cell infiltration, myofibroblastic and osteoblastic differentiation. Subclinical leaflet thrombosis was recently linked to higher rates of stroke and transient ischemic attack after transcatheter aortic valve implantation (TAVI). Procoagulant microparticles (MPs) are associated with ED, inflammation and clot formation. There is limited evidence regarding intra-valvular MPs content and their potential biological effects. This question is particularly relevant in TAVI in which the residing native valve could constitute a source of thrombotic activity enhancing leaflet thrombosis and valve dysfunction.

Purpose

Therefore, we hypothesized that MPs trapped within the native aortic valve contribute to valvular dysfunction including enhanced thrombogenicity.

Methods

Human valves were collected from patients undergoing surgical valve replacement for AS or aortic insufficiency (AI). Pro-thrombotic, pro-inflammatory, and ED markers were identified in the calcified vs non-calcified part of the valves by Western-blot. Calcium content was measured through colorimetric method. MPs were extracted from human pathological valves, and quantified through their prothrombinase activity. Primary cultures of porcine valvular endothelial cells (VEC) were treated with the MPs (10 nmol/L) or thrombin (1U/ml) for 24hrs. Phenotypic change was appreciated through gene expression pattern assessed by RT-qPCR. IL-8 secretion was measured by ELISA.

Results

The phenotype of the AS valve was characterized through increased expression of thrombogenic (tissue factor, thrombomodulin, PAI-1), adhesive (VCAM-1, ICAM-1) and inflammatory (COX-1, COX-2) molecules in the calcified part of the valve. Moreover, MPs content was increased in the calcified vs non-calcified part of the valve or AI valves. MPs levels was correlated with valvular calcium content (R=0.3862: p<0.001). Tissue factor was increased in MPs extracted from AS vs AI. The biological effect of MPs was tested on VEC in-vitro. Results showed dramatic increase in expression of inflammatory cytokines (CXCL10, CCL11, CXCL8, MCP1) adhesion molecules (VCAM-1, ICAM-1, SELP, SELE) and proangiogenic factors (VEGFR2, ANGPTL4) in VEC exposed to MPs (24h) from AS vs AI. Enhanced secretory phenotype was evidenced through IL-8 determination in the supernatant of VEC stimulated with MPs from AS valve.

Conclusion

Calcified aortic valve is a potent reservoir of MPs, acting as a pro-thrombogenic source per se and promoting a switch of VEC phenotype toward prothrombotic, proinflammatory and proangiogenic pattern. These data suggest that MPs released from the native valve constitute an important source of mediators involved in enhanced thrombogenicity and valvular remodeling.

Funding Acknowledgement

Type of funding sources: Other. Main funding source(s): GERCA-Groupe Etudes Reali Commercia Avignon

Protective effects of dapagliflozin on vascular remodeling in the carotid artery following balloon injury – potential role of angiotensin and purinergic signaling

Introduction

Sodium-glucose co-transporter 2 (SGLT2) inhibitors have been shown to reduce the risk of cardiovascular events independently of glycemic control. The possibility that SGLT2 inhibitors improve endothelial regeneration and vascular restenosis is unknown.

Purpose

To examine whether dapagliflozin, a selective SGLT2 inhibitor, could prevent neointima thickening induced by balloon injury and, if so, to determine the underlying mechanisms. The effect of dapagliflozin was compared to that of losartan, an angiotensin type 1 receptor (AT1R) antagonist.

Methods

Saline, dapagliflozin (1.5 mg/kg/day), or losartan (30 mg/kg/day) were administered orally for 5 weeks to male Wistar rats. Balloon injury of the left carotid artery was performed 1 week after starting the treatment and sacrificed 4 weeks later. Vascular reactivity was assessed on left (injured) and right (healthy) carotid artery rings. The extent of neointima was assessed by histomorphometric analysis, changes of target factors by immunofluorescence, RT-qPCR and histochemistry.

Results

Dapagliflozin and losartan treatments reduced neointima thickening by 32% and 27%, respectively. Blunted contractile responses to phenylephrine and relaxations to acetylcholine and down-regulation of eNOS were observed in the injured artery. These effects were not modified by the dapagliflozin or the losartan treatments. RT-qPCR investigations indicated an increased in gene expression of inflammatory (IL-1beta, ITGAM, VCAM-1), oxidative (p47phox, p22phox) and fibrotic (TGF-beta1) markers and a decreased of eNOS in the injured carotid. However, these changes were not affected by the pharmacological treatments. By contrast, significant increased levels of AT1R angiotensin receptor and NTPDase1 (CD39) ectonucleotidase were observed in the restenotic carotid artery of the dapagliflozin group. Histochemical analysis evidenced important NTPDase1 activity in the neointima.

Conclusions

Dapagliflozin effectively reduced neointimal thickening. As the contribution of AT1R and P2Y2 ATP receptor in smooth muscle cell proliferation and neointima formation has been reported in the literature, the present data suggest that dapagliflozin prevents restenosis through interfering with angiotensin and/or extracellular nucleotides signaling. SGLT2 transporter represent potential new target for limiting vascular restenosis.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): This work was supported by AstraZeneca

The adiponectin agonist, AdipoRon, inhibits steroidogenesis and cell proliferation in human luteinized granulosa cells

During obesity, excess body weight is not only associated with an increased risk of type 2-diabetes, but also several other pathological processes, such as infertility. Adipose tissue is the largest endocrine organ of the body that produces adipokines, including adiponectin. Adiponectin has been reported to control fertility through the hypothalamic-pituitary-gonadal axis, and folliculogenesis in the ovaries. In this study, we focused on a recent adiponectin-like synthetic agonist called AdipoRon, and its action in human luteinized granulosa cells. We demonstrated that AdipoRon activated the adenosine monophosphate-activated protein kinase (AMPK) and peroxisome proliferator-activated receptor alpha (PPAR) signalling pathways in human luteinized granulosa cells. A 25 μM AdipoRon stimulation reduced granulosa cell proliferation by inducing cell cycle arrest in G₁, associated with PTEN and p53 pathway activation. In addition, AdipoRon perturbed cell metabolism by decreasing mitochondrial activity and ATP production. In human luteinized granulosa cells, AdipoRon increased phosphodiesterase activity, leading to a drop in cyclic adenosine monophosphate (cAMP) production, aromatase expression and oestrogens secretion. In conclusion, AdipoRon impacted folliculogenesis by altering human luteinized granulosa cell function, via steroid production and cell proliferation. This agonist may have applications for improving ovarian function in metabolic disorders or granulosa cancers.