Hyponatremia and vasopressin antagonism in congestive heart failure

Admission hyponatraemia as heart failure events predictor in patients with acute heart failure

AIMS

Heart failure remained consistent as one of the biggest cardiovascular problems in Indonesia. Hyponatraemia is a common electrolyte disorder among patients presented with heart failure; however, the prognostic value for worsening heart failure has not been well defined.

METHODS AND RESULTS

We studied 134 patients admitted with acute heart failure and investigated the relationship between admission serum sodium and the composite clinical outcomes of all-cause mortality and hospitalization ambispectively with a follow-up duration of 6 months. We also try to look for low sodium-level impacts in several conditions. Among 134 patients, 84 patients presented with low sodium during admission, defined as a serum sodium level of <135 mEq/L, and it was associated with higher composite clinical outcome risk [odds ratio (OR), 5.9; 95% confidence interval (CI), 2.8-12.0; P < 0.001]. Moreover, hyponatraemia impacts on composite endpoints were driven by both parameters; it was independently associated with mortality (OR, 3.1; 95% CI, 1.4-6.8; P = 0.003) and rehospitalization (OR, 5.3; 95% CI, 2.4-11.7; P < 0.001). This result remained consistent in most subgroups.

CONCLUSIONS

On-admission hyponatraemia is a predictor for 6 month mortality and rehospitalization. Further work is needed to determine if correction of hyponatraemia translates into clinical benefit.

Rise of first follow-up sodium in patients hospitalized with acute heart failure is associated with better outcomes

INTRODUCTION

The prognostic effect of the direction of change in sodium (Na) level from admission to subsequent check in patients with acute heart failure (HF) has not been previously explored.

METHODS

The ESCAPE trial data was utilized to study whether the rise of 1^st follow-up Na (at day 3) relative to admission (among patients with admission hyponatremia) is associated with favorable outcomes. The study endpoints were all-cause rehospitalization and a composite of death, rehospitalization and cardiac transplant, both up to 6-month after discharge.

RESULTS

Patients with rise of 1^st follow-up Na (n = 43) had an average admission Na of 130.1 meq/L which increased to 134 meq/L at day 3 (P < 0.001), while patients without rise of 1^st follow up Na (n = 46) had an admission Na of 131 meq/L which decreased to 128.9 meq/L at day 3 (P < 0.001). There was an inverse association between the magnitude of change in Na level from admission to day 3 and the magnitude of change in blood urea nitrogen (BUN, r = -0.304, P = 0.004), creatinine (r = -0.401, P < 0.001) and weight (r = -0.279, P = 0.011) during the same time frame. Among those 89 cases, 56 (63%) were rehospitalized and 70 (79%) experienced the composite endpoint. Patients without rise in 1^st follow-up Na had higher frequency of rehospitalization (76.1% vs. 48.8%, univariate Odds ratio (OR) 1.778, 95% CI 1.174-2.693, P = 0.009) and composite endpoint (89.1% vs. 67.4%, univariate OR 1.779, 95% CI 1.208-2.619, P = 0.017), compared with those with Na rise. Cox regression analysis showed that rise in 1^st follow-up Na was independently associated with reduced rehospitalization (Hazard ratio (HR) 0.429, 95% CI 0.191-0.960, P = 0.04) and the composite endpoint (HR 0.430, 95% CI 0.201-0.920, P = 0.03) after covariate adjustment.

CONCLUSION

Rise of first follow-up Na in patients with HF decompensation and hyponatremia on admission is associated with favorable intermediate-term outcomes.

Prognostic Significance of Discharge Hyponatremia in Heart Failure Patients With Normal Admission Sodium (from the ESCAPE Trial)

Hyponatremia in acute decompensated heart failure (HF) is indicative of a poor prognosis and predicts morbidity and mortality. We explored the predictive utility of hyponatremia at the time of hospital discharge among HF patients with normal admission sodium (Na). Characteristics and outcomes of HF patients enrolled in the Evaluation Study of Congestive Heart Failure and Pulmonary Artery Catheterization Effectiveness trial, who had normal Na on admission, were compared between those who were hyponatremic (Na <135 meq/L) or normonatremic on discharge. Three hundred six patients with normal admission Na had either hyponatremia (n = 86) or normal Na (n = 220) on discharge. Compared with patients with normal Na on discharge, hyponatremic patients were younger (p = 0.004), with lower discharge systolic (p <0.001) and diastolic (p = 0.004) blood pressure, higher discharge blood urea nitrogen (p = 0.011) despite similar creatinine (p = 0.566), lower ejection fraction (p = 0.007), and higher left ventricular end-diastolic (p = 0.028) and end-systolic (p = 0.007) dimensions. Despite comparable congestion on hospital admission, patients with discharge hyponatremia had a higher degree of decongestion throughout hospitalization evident in the significantly greater admission to discharge weight loss (p = 0.044) and admission to discharge reduction in inferior vena cava diameter (p = 0.014). Despite longer initial hospitalization (p = 0.004), total duration in hospital at 30 days (p = 0.004) and 6 months (p = 0.045), there were no significant differences between patients with discharge hyponatremia versus normal Na on discharge regarding rehospitalization (p = 0.386), all-cause mortality (p = 0.440), and composite of death, cardiac rehospitalization, and cardiac transplant (p = 0.799), all up to 6-month following randomization. Restricted cubic spline analysis also showed no significant relationships between discharge Na and the aforementioned 3 outcomes. Cox proportional hazards regressions showed that discharge hyponatremia did not significantly predict any of the 3 outcomes after adjustment for imbalances at baseline. Among patients with discharge hyponatremia, a poor outcome was more likely if they were also hyponatremic on admission: the composite end point occurred in 69.2% of those also hyponatremic on admission versus 51.2% of those with normal Na on admission but decreased Na on discharge (p = 0.045). Because the median discharge Na level in the discharge hyponatremia group was 132 meq/L, our findings suggest a benign nature of mild discharge hyponatremia in HF patients with normal admission Na.

Relationship and mechanism of Kv2.1 expression to ADH secretion in rats with heart failure

OBJECTIVE

To explore the mechanisms of Kv2.1 on the secretion of ADH in rats with heart failure.

METHODS

In the animal study, 70 healthy male SD rats were selected. Ligation of coronary heart failure model surgery was performed in 60 rats and sham surgery was performed in the other 10 rats. Q-PCR was used to detect the mRNA expression of Kv2.1 in hypothalamus and heart. The protein expression of Kv2.1 and ADH was detected by western blot. In the cell culture study, hypothalamic neurons were cultured and divided into 7 groups. The mRNA expression of Kv2.1 and ADH was detected by Q-PCR. The protein expression of Kv2.1, CamKII, phosphorylation SynapsinI, dephosphorylation SynapsinI and ADH was detected by western blot.

RESULTS

Compared with the control group of heart failure, LVEDD, LVESD, LVEDV and LVESV were significantly decreased (P < 0.01), and LVEF and LVFS were significantly increased (P < 0.01) in the Kv2.1 agonist group; in the Kv2.1 inhibitor group, LVEDD, LVESD, LVEDV and LVESV were significantly increased (P < 0.01), and LVEF and LVFS were significantly decreased (P < 0.01). In cell culture study, after the different concentrations of Kv2.1 inhibitor gradient down the expression of Kv2.1, intracellular Ca²⁺ concentration gradient increased (P < 0.01), CamKII and phosphorylation of SynapsinI protein expression gradient increased (P < 0.01), dephosphorylation of SynapsinI protein expression gradient decreased (P < 0.01), and the ADH mRNA and protein expression of gradient increased (P < 0.01).

CONCLUSIONS

Kv2.1 agonist can prevent the calcium overload by reducing the intracellular Ca²⁺ concentration, so that the phosphorylation of SynapsinI reduces and exocytosis in hypothalamic neurons is inhibited, which ease the secretion of ADH.

Predictors of Long-Term Mortality in Patients With Acute Heart Failure

To investigate parameters which were related with long-term mortality in patients hospitalized for acute heart failure (AHF).A total of 287 patients with AHF presenting to the First Affiliated Hospital of Nanjing Medical University were enrolled into the registry from April 2012 to January 2015. The primary endpoint was all-cause mortality within 1 year; the association between variables and prognosis was assessed after 1 year.Among the 287 patients, 17 did not continue follow-up and 47 (17.4%) passed away. Baseline NT-proBNP and sST2 concentrations were higher amongst deceased than among survivors (P < 0.001). Serum sodium concentrations of patients who died were lower (P < 0.001). In receiver operator characteristics (ROC) analyses, the area under the curve (AUC) values for NT-proBNP, sST2, and serum sodium to predict 1-year mortality were 0.699 (95%CI 0.639-0.755), 0.692, (95%CI 0.634-0.747), and 0.694 (95%CI 0.634-0.750), respectively. The optimal cut-off points for NT-proBNP, sST2, and serum sodium were 2137.0 ng/L, 35.711 ng/mL, and 136.6 mmol/L, respectively. In Cox regression analysis, ln-transformed NT-proBNP (HR 1.546, P = 0.039), ln-transformed sST2 (HR1.542, P = 0.049), and serum sodium (HR 0.880, P = 0.000) values reliably predicted long-term mortality after multivariable adjustment.In patients with acute heart failure, NT-proBNP, sST2 and serum sodium are potential predictors of 1-year mortality.

Advanced Heart Failure: Prevalence, Natural History, and Prognosis

Heart failure is a complex clinical syndrome. The natural history of this syndrome is progressive. Advanced heart failure is present when a patient has signs and symptoms of heart failure that are refractory to therapy. Patients with the most advanced disease and worst prognosis can be identified using iterative, integrated clinical assessment of symptom burden, effort intolerance, and cardiac dysfunction. Recognizing the transition to advanced heart failure is necessary for referral to an advanced heart disease program. Advanced heart disease specialists can tailor medical therapies, perform risk stratification, and evaluate candidacy for mechanical support, transplantation, or end-of-life palliative treatment options.

Efficacy and safety of angiotensin-converting enzyme inhibitors in patients with left ventricular systolic dysfunction and hyponatremia

BACKGROUND

The presence of hyponatremia has been perceived to increase the risk of adverse events on initiation of treatment with angiotensin-converting enzyme inhibition in heart failure patients. The aim of this study was to investigate if baseline hyponatremia (plasma Na(+) <135 mmol/L) predicts development of hypotension and renal impairment in patients with myocardial infarction (MI) and left ventricular dysfunction (LVD) treated with angiotensin-converting enzyme inhibitors.

METHODS AND RESULTS

A retrospective analysis was performed with data from the Trandolapril Cardiac Evaluation (TRACE) a double-blind randomized study. Plasma sodium levels were available in 1,731 patients, who were considered as the study population. Patients 3-7 days after MI with left LVD (LVEF ≤0.35), were randomized to trandolapril (n = 876) or placebo (n = 873). Baseline hyponatremia did not predict development of hypotension or worsening renal function after 1 month in patients treated with trandolapril compared with placebo (122 ± 19.1 mm Hg vs 123.2 ± 20.4 mm Hg [P = .84]; and creatinine clearance 57.4 ± 21.4 mL/min vs 55.2 ± 21.0 mL/min [P = .8]). There was no interaction between hyponatremia and the effect of trandolapril (P = .68).

CONCLUSIONS

Mild hyponatremia was not a contraindication for the initiation of treatment with angiotensin-converting enzyme inhibitors in patients with post-MI heart failure.

Angiotensin II induces membrane trafficking of natively expressed transient receptor potential vanilloid type 4 channels in hypothalamic 4B cells

Transient receptor potential vanilloid family type 4 (TRPV4) channels are expressed in central neuroendocrine neurons and have been shown to be polymodal in other systems. We previously reported that in the rodent, a model of dilutional hyponatremia associated with hepatic cirrhosis, TRPV4 expression is increased in lipid rafts from the hypothalamus and that this effect may be angiotensin dependent. In this study, we utilized the immortalized neuroendocrine rat hypothalamic 4B cell line to more directly test the effects of angiotensin II (ANG II) on TRPV4 expression and function. Our results demonstrate the expression of corticotropin-releasing factor (CRF) transcripts, for sex-determining region Y (SRY) (male genotype), arginine vasopressin (AVP), TRPV4, and ANG II type 1a and 1b receptor in 4B cells. After a 1-h incubation in ANG II (100 nM), 4B cells showed increased TRPV4 abundance in the plasma membrane fraction, and this effect was prevented by the ANG II type 1 receptor antagonist losartan (1 μM) and by a Src kinase inhibitor PP2 (10 μM). Ratiometric calcium imaging experiments demonstrated that ANG II incubation potentiated TRPV4 agonist (GSK 1016790A, 20 nM)-induced calcium influx (control 18.4 ± 2.8% n = 5 and ANG II 80.5 ± 2.4% n = 5). This ANG II-induced increase in calcium influx was also blocked by 1 μM losartan and 10 μM PP2 (losartan 26.4 ± 3.8% n = 5 and PP2 19.7 ± 3.9% n = 5). Our data suggests that ANG II can increase TRPV4 channel membrane expression in 4B cells through its action on AT1R involving a Src kinase pathway.

Hyponatremia in patients with heart failure

The present review analyses the mechanisms relating heart failure and hyponatremia, describes the association of hyponatremia with the progress of disease and morbidity/mortality in heart failure patients and presents treatment options focusing on the role of arginine vasopressin (AVP)-receptor antagonists. Hyponatremia is the most common electrolyte disorder in the clinical setting and in hospitalized patients. Patients with hyponatremia may have neurologic symptoms since low sodium concentration produces brain edema, but the rapid correction of hyponatremia is also associated with major neurologic complications. Patients with heart failure often develop hyponatremia owing to the activation of many neurohormonal systems leading to decrease of sodium levels. A large number of clinical studies have associated hyponatremia with increased morbidity and mortality in patients hospitalized for heart failure or outpatients with chronic heart failure. Treatment options for hyponatremia in heart failure, such as water restriction or the use of hypertonic saline with loop diuretics, have limited efficacy. AVP-receptor antagonists increase sodium levels effectively and their use seems promising in patients with hyponatremia. However, the effects of AVP-receptor antagonists on hard outcomes in patients with heart failure and hyponatremia have not been thoroughly examined.

Significance of hyponatremia in heart failure

Heart failure is one of the most common, costly, disabling and growing diseases (McMurray and Pfeffer in Lancet 365(9474):1877-1889, 2005). Hyponatremia, conventionally defined as a serum-sodium concentration equal or less than 135 mmol/l (American Heart Association in Heart disease and stroke statistics--2007 update. American Heart Association, Dallas, 2007; Stewart et al. in Eur J Heart Fail 4:361-371, 2002), is a common phenomenon in patients with heart failure, with an incidence of 20-25% (Krumholz et al. in Arch Intern Med 157:e99-e104, 1997; Rosamond et al. in Circulation 117(4):e25-e146, 2008; Adrogue and Madias in N Engl J Med 342:1581-1589, 2000) and seems to be of prognostic importance in patients with heart failure (Luca et al. in Am J Cardiol 96:19L-23L, 2005; Gheorghiade et al. in Eur Heart J 28:980-988, 2007; Gheorghiade et al. in Arch Intern Med 167:1998-2005, 2007). So far treatment strategies have been limited and burdened by side effects. The development of hyponatremia in the setting of heart failure is related to the arginine vasopressin (AVP) dysregulation. Thus, AVP receptor antagonists are a promising approach to treatment. However, several questions remain: whether there is a cause-and-effect mechanism, if the correction of hyponatremia improves outcomes, and defining the specific cut-off level of serum-sodium that should be used to define hyponatremia. In this review, we aim to summarize the literature on hyponatremia in patients with heart failure within several aspects: incidence in clinical trials and registries, prognostic value, underlying mechanisms, therapeutic options, and possible future perspectives.

Relation between serum sodium levels and prognosis in outpatients with chronic heart failure: neutral effect of treatment with beta-blockers and angiotensin-converting enzyme inhibitors: data from the Italian Network on Congestive Heart Failure (IN-CHF database)

INTRODUCTION

The predictive role of hyponatremia has been tested in acute and chronic heart failure. Sodium level is inversely related with renin-angiotensin-aldersterone system (RAAS) and sympathetic nervous activity but important issues remain unresolved. Our aim was to define the level of hyponatremia able to predict 1-year outcomes and investigate the relation between sodium levels and mortality and the effect of beta-blockers and angiotensin-converting enzyme (ACE) inhibitors on this relation.

METHODS

We analyzed 4670 patients enrolled in the IN-CHF Italian Registry. We controlled the predictivity of hyponatremia, testing it either as a continuous variable and dividing the study sample into three severity groups: group 1 (≥136  mEq/l; n = 4207), group 2 (131-135  mEq/l; n = 389) and group 3 (≤130  mEq/l; n = 74). The linearity of the relationship between sodium levels and mortality was also tested.

RESULTS

Mild-to-moderate and severe hyponatremia (groups 2 and 3) independently predicted the 1-year mortality. The relation between sodium concentration and death was not linear and a decrease of 1  mEq/l of sodium increased death rate only for values of sodium 142.9  mEq/l or less. This relationship was not modified by beta-blocker and ACE inhibitor therapies.

CONCLUSION

Our data confirm the negative prognostic value of hyponatremia, even of moderate degree, independently of the use of recommended treatments for heart failure.

Targeting hyponatremia and hemodynamics in acute decompensated heart failure: is there a role for vasopressin antagonists?

Current treatment of acute decompensated heart failure (ADHF) has not reduced the significant morbidity or mortality associated with this disease, and has promoted drug development aimed at neurohormonal targets. Hypervolemic hyponatremia, which is linked to the nonosmotic release of arginine vasopressin, is associated with a poor prognosis in patients with heart failure (HF). Vasopressin acts on V(2) and V(1a) receptors to cause water retention and vasoconstriction, respectively. Clinical trials have demonstrated that vasopressin receptor antagonists (VRAs) are effective in treating hypervolemic hyponatremia in ADHF without a negative impact on renal function. The small hemodynamic benefit seen with VRA use appeared to result from V(2)-receptor antagonist-induced increase in urine output rather than from a vasodilatory drug effect. VRA use in ADHF trials was associated with minimal symptomatic improvement and no impact on morbidity or mortality. At present, clinical trial evidence does not support the routine use of VRAs in ADHF. Given the favorable renal profile of VRAs, studies on the possible benefit of VRAs in ADHF patients with renal insufficiency and diuretic resistance appear warranted.

Hyponatremia and long-term outcomes in chronic heart failure--an observational study from the Duke Databank for Cardiovascular Diseases

BACKGROUND

Hyponatremia is a well known predictor of short-term outcomes in heart failure (HF); however, its impact on long-term survival in HF patients with systolic dysfunction is not well established.

METHODS AND RESULTS

Using the Duke Databank for Cardiovascular Diseases, we identified 1,045 patients with HF and systolic dysfunction undergoing cardiac catheterization from January 2000 through December 2008. The effect of hyponatremia as independent predictor of all-cause death and cardiovascular death/rehospitalization was examined using a multivariable Cox proportional regression model. Hyponatremia was present in 107/1,045 patients (10.2%). Hyponatremic patients were older, more likely to be anemic, with higher heart rate and levels of blood urea nitrogen, lower blood pressure, and more severe HF. Using an unadjusted analysis, hyponatremia was associated with higher risk of all-cause death (hazard ratio [HR] 1.89, 95% confidence interval [CI] 1.44-2.49; P < .0001) and of cardiovascular death/rehospitalization (HR 1.40, 95% CI 1.11-1.77; P = .005) at 4.5 years. When entered into a multivariable Cox model, hyponatremia remained significant for all-cause death (HR 1.42, 95% CI 1.07-1.88) and for cardiovascular death/rehospitalization (HR 1.45, 95% CI 1.14-1.86).

CONCLUSIONS

Hyponatremia is relatively common in HF patients with LV dysfunction and is independently associated with increased risk of all-cause mortality and cardiovascular mortality/rehospitalization.

Lixivaptan: a novel vasopressin receptor antagonist

Arginine vasopressin, also known as antidiuretic hormone, is a neuropeptide that functions in the maintenance of body water homeostasis. Inappropriate secretion of vasopressin has been implicated in the pathophysiology of multiple diseases, including polycystic kidney disease, syndrome of inappropriate antidiuretic hormone (SIADH) secretion, and the hyponatremia commonly associated with cirrhosis and congestive heart failure. Vasopressin receptor antagonists are novel agents that block the physiologic actions of vasopressin. Lixivaptan is a vasopressin receptor antagonist with high V2 receptor affinity and is now undergoing Phase III clinical trials. Studies so far have demonstrated that lixivaptan is efficacious in the correction of hyponatremia in SIADH, heart failure and liver cirrhosis with ascites, and few adverse effects have been noted. Thus, lixivaptan remains a promising therapeutic modality for the treatment of multiple diseases and prevention of the associated morbidity and mortality associated with hyponatremia.

Inpatient management of patients with volume overload and high filling pressures

The majority of patients with acute decompensated heart failure are admitted with symptoms of congestion. The classic symptoms of "congestive" heart failure reflect fluid overload, that is, orthopnea, paroxysmal nocturnal dyspnea, and peripheral edema; these symptoms can be so dramatic that it is not surprising that patients seek hospitalization. Activation of the renin angiotensin system coupled with sympathetic hyperactivity results in marked sodium retention and high filling pressures that ultimately bring about these congestive symptoms. The treatment goal of patients hospitalized with volume overload and high filling pressures is to improve symptoms by normalizing the filling pressure and volume status without worsening renal function. The current use of diuretics, vasodilators, and ultrafiltration, as well as potential future use of investigational agents such as oral vasopressin antagonists and adenosine A1-receptor antagonists, is surrounded by the important issues of when to stop intravenous therapy in hospitalized patients and the exact mechanism by which the filling pressures are normalized. New data from evidence-based clinical trials and optimal strategies for monitoring fluid overload will help define this issue and ultimately reduce mortality in these patients.

Physiology and pathophysiology of the vasopressinergic system

Arginine vasopressin, a hypothalamic peptide hormone, has multiple physiological functions, including body water regulation, control of blood pressure and effects on body temperature, insulin release, corticotropin release, memory and social behaviour. These functions are achieved via at least three specific G-protein-coupled vasopressin receptors. Development of specific vasopressin receptor antagonists in recent years is helping to elucidate the precise actions of vasopressin at each of these receptor types. The complex signalling and messenger processes which take place after receptor stimulation are now more clearly understood. Vasopressin dysregulation can occur in various disease processes, and a better understanding of the mechanisms underlying physiological synthesis, release and regulation of vasopressin will help in the development of therapies to treat these conditions.