Hyponatremia in Patients with Heart Failure beyond the Neurohormonal Activation Associated with Reduced Cardiac Output: A Holistic Approach.

BACKGROUND: Heart failure (HF) is considered an epidemic disease with considerable morbidity, mortality, and immense healthcare costs. Electrolyte abnormalities are often encountered in patients with HF, posing a diagnostic and therapeutic challenge for clinicians. Hyponatremia affects up to one-third of HF patients and represents an unfavorable prognostic factor. SUMMARY: Low sodium levels in HF are mainly attributed to the neurohormonal activation secondary to decreased effective circulating volume. However, patients with HF often have several comorbidities which may cause or exacerbate the preexisting hyponatremia. Factors that provoke HF, such as alcohol overconsumption, may also be involved in hyponatremia development. Furthermore, drugs which are frequently prescribed to HF patients, especially diuretics, are potential culprits of hyponatremia and should always be addressed since their withdrawal may reverse hyponatremia. Despite the great prevalence and deleterious effects of hyponatremia in these patients, it is often overlooked and consequently undertreated. In this review, we present the mechanisms involved in the development of hyponatremia focusing on those besides neurohormonal activation. We also discuss the proper management of this electrolyte disorder which is frequently complex in patients with HF. KEY MESSAGES: Hyponatremia in patients with HF is not only the result of neurohormonal activation; several comorbidities and frequently used drugs should also be addressed. Hence, a holistic approach is required both for the diagnosis and optimal treatment.

Hyponatremia in Acute Stroke Patients: Pathophysiology, Clinical Significance, and Management Options.

BACKGROUND: Hyponatremia is frequent in acute stroke patients, and it is associated with worse outcomes and increased mortality. SUMMARY: Nonstroke-related causes of hyponatremia include patients' comorbidities and concomitant medications, such as diabetes mellitus, chronic kidney disease, heart failure, and thiazides. During hospitalization, "inappropriate" administration of hypotonic solutions, poor solute intake, infections, and other drugs, such as mannitol, could also lower sodium levels in patients with acute stroke. On the other hand, secondary adrenal insufficiency due to pituitary ischemia or hemorrhage, syndrome of inappropriate antidiuretic hormone secretion, and cerebral salt wasting are additional stroke-related causes of hyponatremia. Although it is yet unclear whether the appropriate restoration of sodium level improves outcomes in patients with acute stroke, the restoration of the volume depletion remains the cornerstone of treatment in hypovolemic hyponatremia. In case of hyper- and euvolemic hyponatremia, apart from the correction of the underlying cause (e.g., withdrawal of an offending drug), fluid restriction, administration of hypertonic solution, loop diuretics, and vasopressin-receptor antagonists (vaptans) are among the therapeutic options. Key Messages: Hyponatremia is frequent in patients with acute stroke. The plethora of underlying etiologies warrants a careful differential diagnosis which should take into consideration comorbidities, concurrent medication, findings from the clinical examination, and laboratory measurements, which in turn will guide management decisions. However, it is yet unclear whether the appropriate restoration of sodium level improves outcomes in patients with acute stroke.

Effects of Angiopoietin-Like 3 on Triglyceride Regulation, Glucose Homeostasis, and Diabetes.

Angiopoietin-like 3 (ANGPTL3) is a regulator of plasma triglyceride (TRG) levels due to its inhibitory action on the activity of lipoprotein lipase (LPL). ANGPTL3 is proteolytically cleaved by proprotein convertases to generate an active N-terminal domain, which forms a complex with ANGPTL8 orchestrating LPL inhibition. ANGPTL3-4-8 mouse model studies indicate that these three ANGPTL family members play a significant role in partitioning the circulating TRG to specific tissues according to nutritional states. Recent data indicate a positive correlation of ANGPTL3 with plasma glucose, insulin, and homeostatic model assessment of insulin resistance (HOMA-IR) in insulin-resistant states. The aim of this review is to critically present the metabolic effects of ANGPTL3, focusing on the possible mechanisms involved in the dysregulation of carbohydrate homeostasis by this protein. Heterozygous and homozygous carriers of ANGPTL3 loss-of-function mutations have reduced risk for type 2 diabetes mellitus. Suggested mechanisms for the implication of ANGPTL3 in carbohydrate metabolism include the (i) increment of free fatty acids (FFAs) owing to the enhancement of lipolysis in adipose tissue, which can induce peripheral as well as hepatic insulin resistance; (ii) promotion of FFA flux to white adipose tissue during feeding, leading to the attenuation of de novo lipogenesis and decreased glucose uptake and insulin sensitivity; (iii) induction of hypothalamic LPL activity in mice, which is highly expressed throughout the brain and is associated with enhanced brain lipid sensing, reduction of food intake, and inhibition of glucose production (however, the effects of ANGPTL3 on hypothalamic LPL in humans need more clarification); and (iv) upregulation of ANGPTL4 expression (owing to the plasma FFA increase), which possibly enhances insulin resistance due to the selective inhibition of LPL in white adipose tissue leading to ectopic lipid accumulation and insulin resistance. Future trials will reveal if ANGPTL3 inhibition could be considered an alternative therapeutic target for dyslipidemia and dysglycemia.

Novel Hypolipidaemic Drugs: Mechanisms of Action and Main Metabolic Effects.

Over the last 3 decades, hypolipidaemic treatment has significantly reduced both Cardiovascular (CV) risk and events, with statins being the cornerstone of this achievement. Nevertheless, residual CV risk and unmet goals in hypolipidaemic treatment make novel options necessary. Recently marketed monoclonal antibodies against proprotein convertase subtilisin/kexin type 9 (PCSK9) have shown the way towards innovation, while other ways of PCSK9 inhibition like small interfering RNA (Inclisiran) are already being tested. Other effective and well tolerated drugs affect known paths of lipid synthesis and metabolism, such as bempedoic acid blocking acetyl-coenzyme A synthesis at a different level than statins, pemafibrate selectively acting on peroxisome proliferator-activated receptor (PPAR)- alpha receptors and oligonucleotides against apolipoprotein (a). Additionally, other novel hypolipidaemic drugs are in early phase clinical trials, such as the inhibitors of apolipoprotein C-III, which is located on triglyceride (TG)-rich lipoproteins, or the inhibitors of angiopoietin-like 3 (ANGPTL3), which plays a key role in lipid metabolism, aiming to beneficial effects on TG levels and glucose metabolism. Among others, gene therapy substituting the loss of essential enzymes is already used for Lipoprotein Lipase (LPL) deficiency in autosomal chylomicronaemia and is expected to eliminate the lack of Low- Density Lipoprotein (LDL) receptors in patients with homozygous familial hypercholesterolaemia. Experimental data of High-Density Lipoprotein (HDL) mimetics infusion therapy have shown a beneficial effect on atherosclerotic plaques. Thus, many novel hypolipidaemic drugs targeting different aspects of lipid metabolism are being investigated, although they need to be assessed in large trials to prove their CV benefit and safety.

Apolipoprotein CIII and diabetes. Is there a link?

Apolipoprotein CIII (ApoCIII), a small protein that resides on the surface of lipoprotein particles, is a key regulator of triglyceride metabolism. The inhibition of lipoprotein lipase (LPL), the increased assembly and secretion of very low-density lipoproteins (VLDL) and the decreased reuptake of triglyceride-rich lipoproteins (TRLs) by the liver are mechanisms associating elevated serum ApoCIII levels and hypertriglyceridemia. ApoCIII concentration is high in individuals with diabetes mellitus, indicating a possible positive correlation with impairment of glucose metabolism. The aim of this review (based on a Pubmed search until August 2018) is to present the possible mechanisms linking ApoCIII and deterioration of carbohydrate homeostasis. ApoCIII enhances pancreatic ß-cells apoptosis via an increase of the cytoplasmic Ca2+ levels in the insulin-producing cells. In addition, overexpression of ApoCIII enhances non-alcoholic fatty liver disease and exacerbates inflammatory pathways in skeletal muscles, affecting insulin signalling and thereby inducing insulin resistance. Moreover, recent studies reveal a possible mechanism of body weight increase and glucose production through a potential ApoCIII-induced LPL inhibition in the hypothalamus. Also, the presence of ApoCIII on the surface of high-density lipoprotein particles is associated with impairment of their antiglycemic and atheroprotective properties. Modulating ApoCIII may be a potent therapeutic approach to manage hypertriglyceridemia and improve carbohydrate metabolism.

Pleiotropic effects of proprotein convertase subtilisin/kexin type 9 inhibitors?

PURPOSE OF REVIEW: Current data suggest that proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors may affect many metabolic pathways beyond lowering LDL cholesterol. The aim of the present manuscript is to present these so-called pleiotropic effects of PCSK9 inhibitors. RECENT FINDINGS: PCSK9 may affect the activity of other receptors beyond LDL receptors (LDLR), such as cluster of differentiation 36 (CD36), very-low-density-lipoprotein (VLDL) receptors, apolipoprotein (Apo) E receptors, LDLR-related protein 1 (LRP-1) and ATP-Binding Cassette Transporter (ABCA1). Thus, a role of PCSK9 in the development of atherosclerosis, in vascular wall inflammation and in platelet function has been suggested. Additionally, PCSK9 inhibitors may affect lipid variables beyond LDL cholesterol, carbohydrate variables, as well as they may affect brain and kidney function. Additionally, a controversial role of PCSK9 in sepsis, hepatitis C infection and Alzheimer's disease has been suggested. SUMMARY: These possible pleiotropic effects of PCSK9 inhibitors need further research, as they may affect cardiovascular risk and provide further insights in the development of atherosclerosis and other diseases such as Alzheimer's disease or chronic viral infection and sepsis.

Non-hemorrhage-related adverse effects of rivaroxaban.

The direct oral anticoagulant rivaroxaban is useful in various indications that include venous deep vein thrombosis prophylaxis/treatment after knee/hip replacement surgery and prevention of stroke in patients with non-valvular atrial fibrillation. Its mechanism of action has been mostly associated with hemorrhage-related adverse effects; thus a number of non-hemorrhage-related adverse effects of the drug have received less attention or go unrecognized. These adverse effects mainly include liver injury, hypersensitivity reactions, leukocytoclastic vasculitis and hair loss. Clinicians should be aware of these rare adverse reactions and advise their patients to contact them as soon as they observe any unexpected clinical response.