The critical link of hypervolemia and hyponatremia in heart failure and the potential role of arginine vasopressin antagonists. J Card Fail. 2010;16:419-431. [PMID: 20447579 DOI: 10.1016/j.cardfail.2009.12.021]

Papel dos Níveis de Sódio na Fibrilação Atrial na Insuficiência Cardíaca: Jogador Ativo ou Bystander?

Fundamento

Objetivo

Métodos

Resultados

Conclusão

Copeptin as a predictive marker of incident heart failure

Aims

Heart failure (HF) is a common disease with increasing prevalence and poor prognosis. The vasopressin (VP) marker copeptin predicts development of diabetes mellitus, diabetic heart disease, coronary artery disease, and premature mortality. Copeptin is elevated in HF patients and predicts a worse outcome. This study aims to investigate whether copeptin can predict HF development.

Methods

Copeptin was analysed in 5297 individuals (69.6% men) without prevalent HF from the Malmö Preventive Project, a population‐based prospective cohort. Cox proportional hazards models were used to analyse risk of incident HF by copeptin levels after adjusting for conventional cardiovascular risk factors.

Results

During a median follow‐up time of 11.1 years, 350 subjects (6.6%) were diagnosed with HF. Of these events, 99 were classified as myocardial infarction (MI) related HF and 251 as non‐MI‐related HF. Individuals in the top quartile of copeptin had, after multivariate adjustment for conventional risk factors (age, sex, systolic blood pressure, diabetes mellitus, body mass index, antihypertensive therapy, smoking, low‐density lipoprotein cholesterol, and high‐density lipoprotein cholesterol), a significantly increased risk of developing HF by 1.63 [confidence interval (CI) 1.20–2.21] for HF compared with the reference quartile 1. After adjustment for conventional risk factors, the hazard ratio (HR) per standard deviation increase of log‐transformed copeptin for any HF was 1.30 (95% CI 1.17–1.46), whereas it was 1.39 (CI 1.13–1.71) for MI‐related HF and 1.26 (CI 1.11–1.44) for non‐MI‐related HF. The associations remained after additional adjustment for estimated glomerular filtration rate [HR 1.24 (95% CI: 1.10–1.40)] and for pro atrial natriuretic peptide on top of conventional risk factors [HR 1.14 (95% CI: 1.02–1.28)].

Conclusions

Elevated copeptin predicts development of HF in older adults. Copeptin is a risk marker of VP‐driven HF susceptibility and a candidate to guide prevention efforts of HF targeting the VP system.

Estimated plasma volume status in heart failure: clinical implications and future directions

Congestion is one of the main predictors of poor outcome in patients with heart failure (HF). Assessing and monitoring congestion is essential for optimizing HF therapy. Among the various available methods, serial measurements of estimated plasma volume (ePVS) using routine blood count and/or body weight (e.g., the Strauss, Duarte, Hakim formulas) may be useful in HF management. Further prospective study is warranted to determine whether ePVS can help optimize decongestion therapy (loop diuretics, mineralocorticoid receptor antagonists, SGLT2i) in various HF settings. This narrative review summarizes the recent evidence supporting the association of ePVS with clinical congestion and outcome(s) and discusses future directions for monitoring ePVS in HF.

Proposal for New Classification and Practical Use of Diuretics According to Their Effects on the Serum Chloride Concentration: Rationale Based on the "Chloride Theory"

Currently, diuretic therapy for heart failure (HF) pathophysiology is primarily focused on the sodium and water balance. Over the last several years, however, chloride (Cl) has been recognized to have an important role in HF pathophysiology, as both a prognostic marker and a possible central factor regulating the body fluid status. I recently proposed a unifying hypothesis for HF pathophysiology, called the "chloride theory", during HF worsening and recovery, as follows. Chloride is the key electrolyte for regulating both reabsorption of tubular electrolytes and water in the kidney through the renin-angiotensin-aldosterone system and distributing body fluid in each compartment of the body. As changes between the serum Cl concentration and plasma volume are intimately associated with worsening HF and its recovery after decongestive therapy, modulation of the serum Cl concentration by careful selection and combination of various diuretics and their doses could become an attractive therapeutic option for HF. In this review, I will propose a new classification and practical use of diuretics according to their effects on the serum Cl concentration. Diuretic use according to this classification is expected to be a useful strategy for the treatment of patients with HF.

Hyponatremia in Heart Failure: Pathogenesis and Management

Hyponatremia is a very common electrolyte abnormality, associated with poor short- and long-term outcomes in patients with heart failure (HF). Two opposite processes can result in hyponatremia in this setting: Volume overload with dilutional hypervolemic hyponatremia from congestion, and hypovolemic hyponatremia from excessive use of natriuretics. These two conditions require different therapeutic approaches. While sodium in the form of normal saline can be lifesaving in the second case, the same treatment would exacerbate hyponatremia in the first case. Hypervolemic hyponatremia in HF patients is multifactorial and occurs mainly due to the persistent release of arginine vasopressin (AVP) in the setting of ineffective renal perfusion secondary to low cardiac output. Fluid restriction and loop diuretics remain mainstay treatments for hypervolemic/dilutional hyponatremia in patients with HF. In recent years, a few strategies, such as AVP antagonists (Tolvaptan, Conivaptan, and Lixivaptan), and hypertonic saline in addition to loop diuretics, have been proposed as potentially promising treatment options for this condition. This review aimed to summarize the current literature on pathogenesis and management of hyponatremia in patients with HF.

Acetazolamide as a potent chloride-regaining diuretic: short- and long-term effects, and its pharmacologic role under the 'chloride theory' for heart failure pathophysiology

According to the "chloride theory" for heart failure (HF) pathophysiology, manipulation of the serum chloride concentration is an important therapeutic target. This study determined the short- and long-term effects of acetazolamide (Diamox), a potential chloride-regaining diuretic, on peripheral blood, serum electrolytes, and renal function. Effects of low-dose Diamox (250-500 mg/day) were evaluated in 30 HF patients for whom Diamox was added as de-novo/add-on decongestion therapy for acutely worsening HF (n = 18) or as modification therapy for serum hypochloremia in stable HF ( < 100 mEq/L; n = 12). Peripheral hematologic tests were performed at baseline, and at short- ( ≤ 10 days) and long-term ( ~ 60 days) time-points. In all 30 study patients of both groups, the serum chloride concentration increased in the short-term and even further over the long-term. The serum potassium concentration constantly decreased throughout the study period. Both the blood urea nitrogen and serum creatinine concentrations increased in the short-term, but returned to baseline levels over the long-term. Responders to Diamox (n = 13; defined by HF resolution and body weight loss ≥ 1 kg) in the decongestion group exhibited reduced serum b-type natriuretic peptide levels and a markedly increased serum chloride concentration, but the hemoglobin/hematocrit and serum creatinine concentrations did not change after treatment. In conclusion, acetazolamide is a potent candidate "chloride-regaining diuretic" for treating HF patients under the "chloride theory". Its effect to enhance the serum chloride concentration occurred within 10 days and persisted for at least ~ 60 days. Plasma volume and renal function were preserved under adequate diuretic treatment with acetazolamide.

The prognosis of heart failure patients: Does sodium level play a significant role?

Introduction

Heart failure (HF), a major cardiovascular disorder, remains a grievous clinical condition regardless of advances in medical care. Hyponatremia is classified as a serum sodium concentration of <135 mEq/L, and the prevalence, clinical impact and prognostic factor of hyponatremia in heart failure patients varies widely. The current study was conducted with the aim of assessing the prevalence of hyponatremia in patients hospitalized with a diagnosis of HF and comparing baseline clinical characteristic of HF patients based on their sodium status. Survival difference between patients with hyponatremia and normonatremia was also assessed and the clinical prognostic indicators of overall mortality in HF patients were evaluated.

Method

A retrospective cohort study was conducted to assess medical records of heart failure patients who were admitted to Gondar University Referral Hospital. Patients were categorized based on their sodium level status at their first admission to the internal medicine department. Each patient was assigned to either of the following groups: hyponatremia if sodium < 135 mmol/L, or normonatremia if sodium ≥ 135 mmol/L.

Result

Among 388 participants, the prevalence of hyponatremia in the study cohorts was 51.03%. Kaplan-Meier survival curves showed that there was a significant difference in survival status of HF patients among the two cohorts (Log—Rank test, P <0.0001). Hence, patients with normal sodium levels had a higher chance of survival over hyponatremic patients. Multivariate Cox regression has revealed a statistically significant association of mortality with the following variables: advanced age (AHR = 1.035 (1.012–1.058), P = 0.003), hyponatremia (AHR = 4.003 (1.778–9.009), P = 0.001), higher creatinine level (AHR = 1.929 (1.523–2.443), P = <0.0001) and, prescription of angiotensin-converting enzyme inhibitors (AHR = 0.410 (0.199–0.842), P = 0.015) and spironolactone (AHR = 0.511 (0.275–0.949), P = 0.033.

Conclusion

In conclusion, hyponatremia is one of the crucial factors in the clinical prognosis of heart failure patients. However, as other prognostic factors (i.e. medication, creatine level, and age) also played vital roles in overall survival, well-controlled clinical trials (complete with medication dosing, laboratory outputs and long-term prospective follow up) are required to further study the impact of hyponatremia in HF patient’s prognosis in low income nations.

Dynamic changes in serum chloride concentrations during worsening of heart failure and its recovery following conventional diuretic therapy: A single-center study

BACKGROUND AND AIMS

Few data are available regarding the dynamic changes in the serum chloride concentrations in heart failure (HF) pathophysiology. The aim of the present study was to investigate changes in the serum chloride concentration under worsening HF and its recovery following conventional diuretic therapy.

METHODS

Blood test data, including measurements of serum albumin/solutes and b-type natriuretic peptide, at both worsening and recovery of HF status, were obtained from 47 patients with definite HF.

RESULTS

Ambulatory patients with HF were enrolled and followed up at the outpatient clinic of Nishida Hospital between June 2003 and March 2009. From clinically stable to worsening HF, the serum sodium concentration increased from (mean ± SD) 139 ± 4.1 to 141 ± 5.07 mEq/L (P < 0.05, two-way analysis of variance) and the serum chloride concentration increased from 101 ± 5.36 to 104 ± 5.44 mEq/L (P < 0.01) among all patients. After resolution of worsening HF by treatment with conventional diuretics, both the serum sodium concentration and serum chloride concentration decreased significantly to 138 ± 5.12 and 99.5 ± 5.33 mEq/L, respectively (P < 0.0001 for each). The absolute changes in the serum sodium concentration from clinically stable HF to worsening HF appeared to be lesser than those in the serum chloride concentration (1.70 ± 4.34 vs 2.72 ± 6.02 mEq/L, P = 0.079, t test), but this was not statistically significant. Absolute changes in the serum sodium concentration from worsening HF to its recovery following treatment with conventional diuretics were lesser than those in the serum chloride concentration (-2.87 ± 4.38 vs -4.45 ± 5.23 mEq/L, P = 0.0068, t test).

CONCLUSION

Under conventional diuretic therapy, greater changes occur in the serum chloride concentration than in the serum sodium concentration under HF state transitions, suggesting that chloride dynamics might contribute more to HF pathophysiology under such therapeutic circumstance.

Prognostic Significance of Baseline Serum Sodium in Heart Failure With Preserved Ejection Fraction

BACKGROUND

The purpose of this study was to evaluate the relationship between serum sodium at the time of diagnosis and long term clinical outcomes in a large national cohort of patients with heart failure with preserved ejection fraction.

METHODS AND RESULTS

We studied 25 440 patients with heart failure with preserved ejection fraction treated at Veterans Affairs medical centers across the United States between 2002 and 2012. Serum sodium at the time of heart failure diagnosis was analyzed as a continuous variable and in categories as follows: low (115.00-134.99 mmol/L), low-normal (135.00-137.99 mmol/L), referent group (138.00-140.99 mmol/L), high normal (141.00-143.99 mmol/L), and high (144.00-160.00 mmol/L). Multivariable Cox regression and negative binomial regression were performed to estimate hazard ratios (95% confidence interval [CI]) and incidence density ratios (95% CI) for the associations of serum sodium with mortality and hospitalizations (heart failure and all-cause), respectively. The average age of patients was 70.8 years, 96.2% were male, and 14% were black. Compared with the referent group, low, low-normal, and high sodium values were associated with 36% (95% CI, 28%-44%), 6% (95% CI, 1%-12%), and 9% (95% CI, 1%-17%) higher risk of all-cause mortality, respectively. Low and low-normal serum sodium were associated with 48% (95% CI, 10%-100%) and 38% (95% CI, 8%-77%) higher risk of number of days of heart failure hospitalizations per year, and with 44% (95% CI, 32%-56%) and 18% (95% CI, 10%-27%) higher risk of number of days of all-cause hospitalizations per year, respectively.

CONCLUSIONS

Both elevated and reduced serum sodium, including values currently considered within normal range, are associated with adverse outcomes in patients with heart failure with preserved ejection fraction.

Proposal for heart failure progression based on the 'chloride theory': worsening heart failure with increased vs. non-increased serum chloride concentration

AIMS

Chloride (Cl) is an established key electrolyte for the activation of the renin-angiotensin-aldosterone system. Recent studies have shown the serum Cl as a key electrolyte for the regulation of body fluid distribution in heart failure (HF) patients. The clinical differences of worsening HF status according to the changes in serum Cl concentration are unclear.

METHODS AND RESULTS

Data from 47 chronic HF patients were analysed. Upon worsening HF, each patient exhibited at least two HF-related signs. Blood tests included haemoglobin (Hb), haematocrit (Ht), mean red blood cell volume (MCV), albumin, serum solutes, and b-type natriuretic peptide. The relative change in the plasma volume (%PV) from stable to worsening HF was estimated as follows: 100 × {Hb (stable) × [1 - Ht (worse)]}/{Hb (worse) × [1 - Ht (stable)]} - 100. When patients were divided into two groups based on changes in serum Cl concentration from stable to worsening HF, the pathophysiologic features of the patients with increased Cl (range 1-23 mEq/L; n = 31) included a greater increase in serum sodium (2.94 ± 4.15 vs. -0.69 ± 3.75 mEq/L, P = 0.005), higher vascular expansion (12 ± 11.1 vs. 4.81 ± 7.94%, P = 0.026), a tendency towards a greater MCV (1.23 ± 2.36 vs. -0.06 ± 1.88 fL, P = 0.065), and preserved renal function defined by the absence of an increase of serum creatinine (-0.24 ± 0.39 vs. -0.05 ± 0.12 mg/dL, P = 0.057) compared to patients with non-increased Cl (range -9 to 0 mEq/L; n = 16). Clinically, the increased Cl group had fewer HF signs (2.65 ± 0.71 vs. 3.31 ± 0.79, P = 0.005) although the change in symptoms did not differ between groups (48% vs. 63%, P = 0.54).

CONCLUSIONS

The present study suggests a new clinical entity of worsening HF status, that is, HF with increased vs. non-increased serum Cl concentration from clinical stability to worsening HF.

Efficacy and safety of dapagliflozin in patients with type 2 diabetes and concomitant heart failure

AIM

We investigated the efficacy and safety of dapagliflozin, a sodium-glucose cotransporter 2 inhibitor, in patients with type 2 diabetes mellitus (T2DM) and heart failure (HF).

METHODS

Data for patients randomized to dapagliflozin 10mg or placebo with a history of HF were pooled from five clinical trials. HbA_1c, weight and systolic blood pressure (SBP; two studies) were examined up to 52weeks using longitudinal repeated-measures models. Composite cardiovascular outcomes, hospitalizations for HF (HHF), and adverse events (AEs) were also assessed.

RESULTS

Patients (mean age 64years, T2DM duration ~14years, HbA_1c 8.2%, ~50% with New York Heart Association Class ≥II) received dapagliflozin (N=171) or placebo (N=149). Dapagliflozin produced clinically meaningful placebo-adjusted reductions in HbA_1c (-0.55%; 95% confidence interval [CI]: -0.80, -0.30), weight (-2.67kg; 95% CI: -3.88, -1.47), and SBP (-2.05mmHg; 95% CI: -5.68, 1.57) over 52weeks. HHF was rare, but numerically lower with dapagliflozin (n=1 [0.6%]) vs placebo (n=7 [4.7%]). Point estimates for hazard ratios of composite cardiovascular outcomes favored dapagliflozin vs placebo, although 95% CIs crossed unity.

CONCLUSIONS

Dapagliflozin produced clinically meaningful reductions in HbA_1c, weight, and SBP in patients with T2DM and HF, and was well tolerated.

Vasopressin and Vasopressin Antagonists in Heart Failure

Despite the introduction of multiple new pharmacological agents over the past three decades in the field of heart failure (HF), overall prognosis remains poor. Hyponatremia is prevalent in HF patients and has been suggested as a contributor to poor response to standard therapy. Elevated levels of arginine vasopressin (AVP), a peptide hormone produced in the hypothalamus, play a role in development of hyponatremia, and AVP and its surrogate, copeptin, are related to changes in osmolality, hemodynamics, neuro-hormones as well as in overall outcome in HF patients. Of current pharmacological interest are the selective and non-selective vasopressin receptor antagonists (VRAs), which inhibit vasoconstriction and cardiac remodeling mediated by the V_1a receptors in smooth blood vessels, and water retention (increased urine osmolality and decreased water excretion) by increasing aquaporin-2 water channels mediated by the V₂ receptors in the renal collecting tubules. The optimal use of VRAs is yet to be determined, especially in patients with congestive HF. Although long-term effects on improvement in mortality have not been shown in the Efficacy of Vasopressin Antagonism in Heart Failure Outcome Study with Tolvaptan (EVEREST) trial, the only long-term outcome trial to date, many short-term studies indicate beneficial aquaretic- and hemodynamic-effects of the VRAs. In contrast to loop diuretics, these new agents tend to increase urine flow and the excretion of electrolyte-free water (so-called aquaresis) in patients with HF, without substantial changes in sodium or potassium excretion. This chapter reviews the role of AVP and copeptin in HF, and the treatment potential of VRAs in HF.

Approach to Hyponatremia in Congestive Heart Failure: A Survey of Canadian Specialist Physicians and Trainees

Background

Hyponatremia is a recognized complication of congestive heart failure (CHF) and is associated with reduced survival. Therefore, early identification and appropriate management of hyponatremia is important. The aim of this study was to determine the general approach amongst Canadian healthcare practitioners and trainees to the identification and management of hyponatremia complicating CHF.

Methods

Respondents completed 15 multiple-choice style questions in 3 case scenarios regarding the approach to management of hyponatremia complicating CHF using an online survey on UKidney.com between November 2012 and May 2013. Results were presented as a proportion of averaged correct/incorrect responses amongst Canadian nephrologists, cardiologists, internists and trainees in each of two domains; pathophysiology and management. Management was further subdivided into correct and incorrect use of diuretic therapy, hypertonic saline, oral urea tablets, vasopressin receptor antagonists (vaptans) and rate of sodium correction. Correct responses were determined by an expert panel of Canadian nephrologists and cardiologists based on review of evidence informed guidelines and current recommendations.

Results

There were 1757 responses to our online survey amongst 455 Canadian respondents, 1139 of which were from cardiologists, nephrologists, general internists, or trainees. Overall, the pathophysiology governing hyponatremia in CHF was correctly identified 68.7 % of the time (n = 380 responses, averaged over 4 questions). Hyponatremia was managed inappropriately 43.6 % of the time, with trainees scoring best overall with correct responses 60.3 % of the time (n = 759 responses, over 11 questions). Importantly, an incorrect rate for sodium correction was selected 61.1 % of the time overall, (n = 211 responses, averaged over 3 questions).

Conclusions

This study identified that there are differences in the understanding of pathophysiology and management strategies for hyponatremia in the context of CHF amongst Canadian specialist physicians and trainees. A more consistent approach to hyponatremia is required and might best be achieved through formal knowledge translation.

Electronic supplementary material

The online version of this article (doi:10.1186/s40697-016-0094-9) contains supplementary material, which is available to authorized users.

Hyponatremia during hospitalization and in-hospital mortality in patients hospitalized from heart failure

Background

To date, the majority of studies on hyponatremia focussed on hyponatremia at admission, and came from developed countries. This study aimed to identify the prevalence of hyponatremia during hospitalization in patients hospitalized for HF and its association with in-hospital mortality.

Methods

This was an observational study using retrospective data from patients’ records between 2010–2013. It focused on those patients carrying an ICD-10 code of 150.0(Congestive Heart Failure) as their primary diagnosis.

Hyponatremia during hospitalization was defined as serum sodium level lower than 135 mEq/L obtained from a blood chemistry measurement on the next days after admission. Patients’ characteristics were examined and the association between hyponatremia during hospitalization and in-hospital mortality was analyzed.

Results

Among 464 patients hospitalized for HF, hyponatremia during hospitalization was observed in 22 % of patients with 44 % of this group had normal serum sodium level on admission.

Hyponatremia during hospitalization was associated with lower blood pressure on admission, both systolic and diastolic, peripheral oedema, ascites and fatigue. Patients having history of hospitalization for cardiac diseases and renal failure were higher in patients developing hyponatremia during hospitalization. In this group, amiodarone, heparin, insulin and antibiotics were administered more frequently. Factors potentially increase the risk of hyponatremia during hospitalization include history of fatigue (OR = 3.23, 95 % CI 1.79–5.82), presence of ascites (4.14, 1.84–9.31), and administration of heparin (3.85, 1.78–8.31) and antibiotics (3.08, 1.71–5.53). Length of hospital stay was significantly longer in patients with hyponatremia during hospitalization and in-hospital mortality was also higher compared to non-hyponatremic patients, 7.7 % and 29.1 %, respectively.

Conclusion

This study found that the prevalence of hyponatremia during hospitalization in patients hospitalized for HF was almost the same as hyponatremia on admission and administration of heparin and antibiotics can potentially worsen hyponatremia during hospitalization. In this study population, hyponatremia during hospitalization was found to be associated with in-hospital mortality.

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.

Evaluation of lixivaptan in euvolemic and hypervolemic hyponatremia and heart failure treatment

INTRODUCTION

Lixivaptan is a selective vasopressin type 2 (V2) receptor antagonist that induces aquaresis, the electrolytes sparing excretion of water. Its ability to correct hyponatremia has been demonstrated in experimental animal studies as well as in clinical trials in humans. Recently, three Phase III, double-blind, randomized, placebo-controlled studies have been completed. In two studies, patients with euvolemic hyponatremia were enrolled, one in the inpatient and the other in the outpatient setting and the third study involved patients with hypervolemic hyponatremia hospitalized for decompensated heart failure (HF). The trials confirmed the efficacy of lixivaptan in raising serum sodium but raised concern about its safety in patients hospitalized with decompensated HF.

AREAS COVERED

The authors review original publications on lixivaptan and summarize their findings. Specifically, the authors present information regarding its structure, pharmacodynamics and kinetics, metabolism as well as its efficacy and safety in laboratory animals and human studies. Furthermore, the FDA website was accessed to obtain information presented at the September 13, 2012 meeting of the Cardiovascular and Renal Drugs Advisory Committee.

EXPERT OPINION

The published data indicate that lixivaptan raises sodium levels in hyponatremic patients and supports its use in patients with euvolemic hyponatremia. However, the authors note that more safety data are still needed specifically in patients with decompensated HF.

Association of hyponatremia and elevated copeptin with death and need for transplantation in ambulatory patients with chronic heart failure

Baseline values, serial measurements, or both of multiple biomarkers (copeptin, a peptide co-secreted with arginine vasopressin; hyponatremia; B-type natriuretic peptide [BNP]; and cardiac troponin T [cTnT]) may improve risk stratification in outpatients with chronic heart failure. A cohort of 157 patients with class III or IV heart failure was prospectively evaluated every 3 months over 2 years with regard to biomarker levels and risk for death or cardiac transplantation. Copeptin ≥40 pmol/L (cohort fourth quartile value), hyponatremia (≤135 mEq/L), BNP >3 times the upper range limitation of normal adjusted for age and gender, and cTnT ≥0.01 ng/ml were pre hoc determined cut points. After multivariate time-dependent regression analysis, copeptin (hazard ratio [HR] 2.26, 95% confidence interval [CI] 1.2 to 4.3, p = 0.014) and BNP (HR 1.89, 95% CI 1.0 to 3.5, p = 0.047), but not hyponatremia, were associated with the primary end point of death or cardiac transplantation. In contrast to univariate prediction of mortality and transplantation, hyponatremia (HR 1.74, 95% CI 0.9 to 3.4, p = 0.099) and cTnT ≥0.01 ng/ml (HR 1.89, 95% CI 1.0 to 3.7, p = 0.064) were not predictive in multivariate models. Interaction models of copeptin with hyponatremia, adjusted for BNP and cTnT, improved the predictive capacity of serial measurements (HR 4.20, 95% CI 1.6 to 8.9, p = 0.004). In conclusion, marked elevations of copeptin, particularly in serial measurements, are independent predictors of poor outcomes. The combination of elevated copeptin with hyponatremia, when adjusted for BNP and cTnT, is an even stronger predictor. These markers appear to reflect activation of the arginine vasopressin system present even in the absence of overt clinical changes. A strategy of serial monitoring of copeptin in combination with hyponatremia may be valuable in identifying higher risk patients with heart failure.

Copeptin in the assessment of acute lung injury and cardiogenic pulmonary edema

BACKGROUNDS

Copeptin has been studied as an excellent predictor of outcome in a variety of diseases, its value is even superior to that of B-type natriuretic peptide (BNP) in heart failure, but little is known about its characteristics in acute respiratory distress syndrome (ARDS)/acute lung injury (ALI). We sought to assess the diagnostic and prognostic value of copeptin together with N-terminal pro-BNP (NT-proBNP) in patients with ARDS/ALI or cardiogenic pulmonary edema (CPE).

METHODS

Measurement of copeptin and NT-proBNP levels in plasma from 121 consecutive patients with either ARDS/ALI or CPE enrolled in a prospective single center study.

RESULTS

In a derivation cohort of 87 patients with ARDS/ALI and 34 patients with CPE, a copeptin threshold of >40.11 pmol/L provided a specificity of 88.2% and a sensitivity of 60.9% for the diagnosis of ARDS/ALI, a NT-proBNP cut point of <2813 pg/ml had a specificity of 79.4% and sensitivity of 65.5% for it. Multivariate Cox regression analysis showed that copeptin was the strongest predictor for mortality in patients with ARDS/ALI [hazard ratio (HR) = 4.72, P < 0.001] and CPE (HR = 3.52, P = 0.019), the association between increasing copeptin and death was statistically significant in patients with ARDS/ALI (HR = 2.64, P = 0.035) and patients with CPE (HR = 1.62, P = 0.029).

CONCLUSION

Copeptin of >40.11 pmol/L had a high specificity for the diagnosis of ARDS/ALI in patients presenting with ARDS/ALI or CPE. Compared to NT-proBNP, copeptin was a stronger prognostic marker for short-term mortality.

Preoperative hyponatremia predicts outcomes after cardiac surgery

OBJECTIVE

To study the effect of preoperative hyponatremia (Na <135 mEq/L) on outcomes after cardiac surgery.

METHODS

From 2002 to 2008, 4370 patients had cardiac surgery at our institution (CABG in 2238, valve in 597, CABG valve in 537, other in 998). The institution electronic medical records, STS database, and Social Security death index data were analyzed. The association of hyponatremia with mortality, hospital length of stay (LOS), and complications was analyzed using regression analysis.

RESULTS

Prevalence of hyponatremia was 21%. Patients with preoperative hyponatremia had lower left ventricular ejection fraction (39% ± 17% versus 46% ± 14%, P < 0.001) and glomerular filtration rate (69 ± 32 mg/min/1.73 m(2)versus 74 ± 27 mg/min/1.73 m(2), P < 0.001) and higher median EuroSCORE (19% versus 9%, P < 0.001), NYHA class 3-4 (77% versus 65%, P < 0.001), prevalence of chronic obstructive pulmonary disease (25% versus 18%, P < 0.001), and arteriopathy (20% versus 13%, P < 0.001). Hyponatremia was associated with increased early mortality (9% versus 4%, P < 0.001), late mortality (24% versus 16%, P < 0.001), and LOS (13 versus 8 d, P < 0.001). Mortality increased with the severity of hyponatremia. After adjusting for baseline and operative variables, hyponatremia was associated with increased hazard of mortality (hazard ratio [HR] 1.31, 95% confidence interval [CI] 1.14-1.52, P < 0.001), risk of early mortality (odds ratio [OR] 1.52, 95% CI 1.09-2.12, P < 0.001), late mortality (HR 1.37, 95% CI 1.16-1.62, P < 0.001), LOS (multiplier 1.26, 95% CI 1.15-1.39, P < 0.001), operative complications (OR 1.30, 95% CI 1.00-1.69, P = 0.051), and dialysis (OR 1.64, 95% CI 1.11-2.44, P = 0.013).

CONCLUSIONS

Preoperative hyponatremia is common, especially in high-risk patients. It is an independent risk factor for mortality, prolonged hospitalization, and complications after cardiac surgery.

Management of hyponatremia in heart failure: role of tolvaptan

BACKGROUND

Asymptomatic or clinically mild hyponatremia commonly occurs in the setting of heart failure, especially among elderly and severely decompensated, fluid-overloaded patients, and is associated with increased morbidity and mortality. Successful detection and treatment of hyponatremia by cardiovascular and advanced practice nurses caring for patients with heart failure are part of multidisciplinary team care. Nurses should be able to detect signs and symptoms of hyponatremia and, even when patients are asymptomatic, initiate appropriate treatment promptly to prevent complications.

PURPOSE

In this review, the epidemiology and pathophysiology of hyponatremia in heart failure, and signs and symptoms are described. In patients with heart failure, challenges involved in determining the type of hyponatremia (hypervolemic, hypovolemic, or euvolemic) and in correctly managing hyponatremia to prevent serious complications are presented. Conventional treatment options and their limitations are reviewed, and the vasopressin-receptor antagonist tolvaptan, an emerging oral therapy option, is introduced and discussed.

CONCLUSIONS

Hyponatremia is a marker of morbidity and mortality in patients with heart failure. Nurses working collaboratively with other healthcare providers must be able to recognize the condition and understand treatment options, including potential adverse effects of current and emerging therapies. One emerging therapy--tolvaptan--can be used in hypervolemic and euvolemic hyponatremic patients with heart failure to correct serum sodium level without negatively affecting renal function.

CLINICAL IMPLICATIONS

Improved nurse understanding of hyponatremia in patients with heart failure may promote nurse-initiated or nurse-facilitated detection and management, which could decrease mortality and morbidity.

The efficacy and safety of lixivaptan in outpatients with heart failure and volume overload: results of a multicentre, randomized, double-blind, placebo-controlled, parallel-group study

AIMS

Volume overload is the dominant feature of decompensated heart failure (HF) and it often results in adverse clinical outcomes. Vasopressin receptor antagonists such as lixivaptan may provide effective volume unloading. This study assessed weight loss after 1 day and 8 weeks of treatment with lixivaptan in outpatients with HF and volume overload.

METHODS AND RESULTS

This phase II, 8-week, multicentre, double-blind, parallel-group study randomized participants (2:1) to receive lixivaptan 100 mg or placebo once daily (in addition to standard HF therapy). Body weight and cardiovascular assessments were made at baseline, Day 1 (not cardiovascular), Weeks 1, 2, 4, and 8, and 7 days post-treatment. The Trail-making Test, part B (TMT-B) and the Medical Outcomes Survey 6-item cognitive function scale (MOS-6) were assessed at baseline and Week 4. The study randomized 170 participants (lixivaptan, n = 111; placebo, n = 59). Most (97.1%) were receiving pharmacological therapy for HF at baseline. Demographic characteristics were generally similar between the two groups. Body weight decreased significantly from baseline to Day 1 with lixivaptan vs. placebo (least-square mean change ± standard error: - 0.38 ± 0.08 kg vs. +0.13 ± 0.11 kg; P < 0.001) and at Weeks 1, 2, and 4 (P < 0.01). Cardiovascular changes were generally similar in both groups, though orthopnoea and dyspnoea improved in the lixivaptan group vs. placebo. The TMT-B and MOS-6 showed no significant differences between groups. Lixivaptan was well tolerated-thirst and polyuria occurred more frequently vs. placebo.

CONCLUSIONS

In outpatients with HF and volume overload, lixivaptan 100 mg once daily, when added to standard therapy, reduced body weight, improved dyspnoea and orthopnoea, and was well tolerated.

TRIAL REGISTRATION

NCT01055912.

Oxytocin and vasopressin agonists and antagonists as research tools and potential therapeutics

We recently reviewed the status of peptide and nonpeptide agonists and antagonists for the V(1a), V(1b) and V(2) receptors for arginine vasopressin (AVP) and the oxytocin receptor for oxytocin (OT). In the present review, we update the status of peptides and nonpeptides as: (i) research tools and (ii) therapeutic agents. We also present our recent findings on the design of fluorescent ligands for V(1b) receptor localisation and for OT receptor dimerisation. We note the exciting discoveries regarding two novel naturally occurring analogues of OT. Recent reports of a selective VP V(1a) agonist and a selective OT agonist point to the continued therapeutic potential of peptides in this field. To date, only two nonpeptides, the V(2) /V(1a) antagonist, conivaptan and the V(2) antagonist tolvaptan have received Food and Drug Administration approval for clinical use. The development of nonpeptide AVP V(1a), V(1b) and V(2) antagonists and OT agonists and antagonists has recently been abandoned by Merck, Sanofi and Pfizer. A promising OT antagonist, Retosiban, developed at Glaxo SmithKline is currently in a Phase II clinical trial for the prevention of premature labour. A number of the nonpeptide ligands that were not successful in clinical trials are proving to be valuable as research tools. Peptide agonists and antagonists continue to be very widely used as research tools in this field. In this regard, we present receptor data on some of the most widely used peptide and nonpeptide ligands, as a guide for their use, especially with regard to receptor selectivity and species differences.

Prevalence and prognostic significance of hyponatraemia in outpatients with chronic heart failure

AIM

Hyponatraemia has been reported to be a potent predictor of poor outcome in patients hospitalized for heart failure (HF). The aim of the study was to determine the prevalence and prognostic significance of hyponatraemia in a large cohort of HF outpatients followed in clinics participating in the Danish Heart Failure Clinics Network.

METHODS AND RESULTS

The study population consisted of consecutive patients referred for HF management in 18 Danish heart failure clinics. Overall, 2863 patients (83%) had a normal plasma sodium (p-sodium) level and 602 patients (17%) had hyponatraemia with a p-sodium level <136 mmol/L. Outcome data were obtained from a validated, national registry. Patients were elderly with a mean age of 68 years. The mean P-[Na+] was 139.6 ± 2.4 mmol/L among patients with normonatraemia and 132.4 ± 3.2 mmol/L among patients with hyponatraemia. In multivariate Cox Proportional Hazard Models adjusted for confounders (age, gender, hospitalization within the last 90 days, loop diuretics, creatinine level, systolic blood pressure, New York Heart Association class III-IV, left ventricular ejection fraction <0.46, ischaemic heart disease and diabetes) hyponatraemic patients had increased risk of hospitalization or death [hazard ratio (HR) 1.2 (95% confidence interval (CI) 1.0-1.4, P = 0.011)]. Hyponatraemia was also an independent predictor of all-cause mortality [HR 1.5 (95% CI 1.2-1.9, P< 0.001)]. There was no interaction between hyponatraemia and the covariables on outcome in the multivariable models.

CONCLUSION

The presence of hyponatraemia in outpatients with HF is associated with increased risk of hospitalization or death.