Response of Novel Biomarkers to BNP Infusion in Patients with Decompensated Heart Failure: A Multimarker Paradigm

Antidiuretic Hormone and Serum Osmolarity Physiology and Related Outcomes: What Is Old, What Is New, and What Is Unknown?

CONTEXT

Although the physiology of sodium, water, and arginine vasopressin (AVP), also known as antidiuretic hormone, has long been known, accumulating data suggest that this system operates as a more complex network than previously thought.

EVIDENCE ACQUISITION

English-language basic science and clinical studies of AVP and osmolarity on the development of kidney and cardiovascular disease and overall outcomes.

EVIDENCE SYNTHESIS

Apart from osmoreceptors and hypovolemia, AVP secretion is modified by novel factors such as tongue acid-sensing taste receptor cells and brain median preoptic nucleus neurons. Moreover, pharyngeal, esophageal, and/or gastric sensors and gut microbiota modulate AVP secretion. Evidence is accumulating that increased osmolarity, AVP, copeptin, and dehydration are all associated with worse outcomes in chronic disease states such as chronic kidney disease (CKD), diabetes, and heart failure. On the basis of these pathophysiological relationships, an AVP receptor 2 blocker is now licensed for CKD related to polycystic kidney disease.

CONCLUSION

From a therapeutic perspective, fluid intake may be associated with increased AVP secretion if it is driven by loss of urine concentration capacity or with suppressed AVP if it is driven by voluntary fluid intake. In the current review, we summarize the literature on the relationship between elevated osmolarity, AVP, copeptin, and dehydration with renal and cardiovascular outcomes and underlying classical and novel pathophysiologic pathways. We also review recent unexpected and contrasting findings regarding AVP physiology in an attempt to explain and understand some of these relationships.

Utility of copeptin for predicting long-term clinical outcomes in patients with heart failure

BACKGROUND

Copeptin, a surrogate marker of pro-arginine vasopressin, is expected to be a marker in cardiovascular diseases. Its utility for predicting long-term clinical outcomes in heart failure (HF), however, has not been adequately evaluated in daily clinical practice in Japan.

METHODS

To assess the relationship of serum copeptin at admission with long-term clinical outcomes, we evaluated serum copeptin at admission in consecutive 107 patients hospitalized for HF between April 2011 and July 2012. The primary outcome measure was defined as a composite of all-cause death and re-admission for HF (all-cause death/HF).

RESULTS

In this study population, median serum copeptin at admission was 15.5 (6.7-32.0)pmol/L. As compared with the low-copeptin group (<18pmol/L, N=60), the high-copeptin group (≥18pmol/L, N=47) included more male patients and those with prior myocardial infarction, prior HF, low left ventricular ejection fraction, and chronic kidney disease. During median 4.5 (1.0-5.5) years of clinical follow-up, the cumulative incidence of all-cause death/HF was significantly higher in the high-copeptin than in the low-copeptin group (63.4% versus 33.0% at 1 year, and 85.2% versus 77.2% at 5 years, log-rank p=0.03). After adjusting for confounders, high-copeptin was still an independent predictor for all-cause death/HF [hazard ratio (95% confidence interval): 1.77 (1.04-3.01), p=0.03].

CONCLUSION

Copeptin was suggested as a useful marker for predicting long-term clinical outcomes in patients with HF.

Prognostic role of copeptin with all-cause mortality after heart failure: a systematic review and meta-analysis

BACKGROUND

As the C-terminal section of vasopressin precursor, copeptin has been recently suggested as a new prognostic biomarker after heart failure (HF). Thus, the aim of this study was to evaluate the prognostic value of plasma copeptin level with all-cause mortality in patients with HF.

METHODS

Comprehensive strategies were used to search relevant studies from electronic databases. Pooled hazard ratios (HRs) and standardized mean differences (SMDs) together with their 95% confidence intervals (CIs) were calculated. Subgroup analysis and sensitivity analysis were performed to find the potential sources of heterogeneity.

RESULTS

A total of 5,989 participants from 17 prospective studies were included in this meta-analysis. A significant association was observed between circulating copeptin levels and risk of all-cause mortality in patients with HF (categorical copeptin: HR =1.69, 95% CI =1.42-2.01; per unit copeptin: HR =1.03, 95% CI =1.00-1.07; log unit copeptin: HR =3.26, 95% CI =0.95-11.25). Pooled SMD showed that copeptin levels were significantly higher in patients with HF who died during the follow-up period than in survivors (SMD =1.19, 95% CI =0.81-1.57). Subgroup analyses also confirmed this significant association, while sensitivity analyses indicated that the overall results were stable.

CONCLUSION

This study demonstrated that circulating copeptin seemed to be a novel biomarker to provide better prediction of all-cause mortality in patients with HF.

B-type natriuretic peptide-guided treatment for heart failure

BACKGROUND

Heart failure is a condition in which the heart does not pump enough blood to meet all the needs of the body. Symptoms of heart failure include breathlessness, fatigue and fluid retention. Outcomes for patients with heart failure are highly variable; however on average, these patients have a poor prognosis. Prognosis can be improved with early diagnosis and appropriate use of medical treatment, use of devices and transplantation. Patients with heart failure are high users of healthcare resources, not only due to drug and device treatments, but due to high costs of hospitalisation care. B-type natriuretic peptide levels are already used as biomarkers for diagnosis and prognosis of heart failure, but could offer to clinicians a possible tool to guide drug treatment. This could optimise drug management in heart failure patients whilst allaying concerns over potential side effects due to drug intolerance.

OBJECTIVES

To assess whether treatment guided by serial BNP or NT-proBNP (collectively referred to as NP) monitoring improves outcomes compared with treatment guided by clinical assessment alone.

SEARCH METHODS

Searches were conducted up to 15 March 2016 in the Cochrane Central Register of Controlled Trials (CENTRAL) in the Cochrane Library; MEDLINE (OVID), Embase (OVID), the Database of Abstracts of Reviews of Effects (DARE) and the NHS Economic Evaluation Database in the Cochrane Library. Searches were also conducted in the Science Citation Index Expanded, the Conference Proceedings Citation Index on Web of Science (Thomson Reuters), World Health Organization International Clinical Trials Registry and ClinicalTrials.gov. We applied no date or language restrictions.

SELECTION CRITERIA

We included randomised controlled trials of NP-guided treatment of heart failure versus treatment guided by clinical assessment alone with no restriction on follow-up. Adults treated for heart failure, in both in-hospital and out-of-hospital settings, and trials reporting a clinical outcome were included.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected studies for inclusion, extracted data and evaluated risk of bias. Risk ratios (RR) were calculated for dichotomous data, and pooled mean differences (MD) (with 95% confidence intervals (CI)) were calculated for continuous data. We contacted trial authors to obtain missing data. Using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach, we assessed the quality of the evidence and GRADE profiler (GRADEPRO) was used to import data from Review Manager to create a 'Summary of findings' table.

MAIN RESULTS

We included 18 randomised controlled trials with 3660 participants (range of mean age: 57 to 80 years) comparing NP-guided treatment with clinical assessment alone. The evidence for all-cause mortality using NP-guided treatment showed uncertainty (RR 0.87, 95% CI 0.76 to 1.01; patients = 3169; studies = 15; low quality of the evidence), and for heart failure mortality (RR 0.84, 95% CI 0.54 to 1.30; patients = 853; studies = 6; low quality of evidence).The evidence suggested heart failure admission was reduced by NP-guided treatment (38% versus 26%, RR 0.70, 95% CI 0.61 to 0.80; patients = 1928; studies = 10; low quality of evidence), but the evidence showed uncertainty for all-cause admission (57% versus 53%, RR 0.93, 95% CI 0.84 to 1.03; patients = 1142; studies = 6; low quality of evidence).Six studies reported on adverse events, however the results could not be pooled (patients = 1144; low quality of evidence). Only four studies provided cost of treatment results, three of these studies reported a lower cost for NP-guided treatment, whilst one reported a higher cost (results were not pooled; patients = 931, low quality of evidence). The evidence showed uncertainty for quality of life data (MD -0.03, 95% CI -1.18 to 1.13; patients = 1812; studies = 8; very low quality of evidence).We completed a 'Risk of bias' assessment for all studies. The impact of risk of bias from lack of blinding of outcome assessment and high attrition levels was examined by restricting analyses to only low 'Risk of bias' studies.

AUTHORS' CONCLUSIONS

In patients with heart failure low-quality evidence showed a reduction in heart failure admission with NP-guided treatment while low-quality evidence showed uncertainty in the effect of NP-guided treatment for all-cause mortality, heart failure mortality, and all-cause admission. Uncertainty in the effect was further shown by very low-quality evidence for patient's quality of life. The evidence for adverse events and cost of treatment was low quality and we were unable to pool results.

Copeptin in Heart Failure

Heart failure (HF) is one of the most common causes of hospitalization and mortality in the modern Western world and an increasing proportion of the population will be affected by HF in the future. Although HF management has improved quality of life and prognosis, mortality remains very high despite therapeutic options. Medical management consists of a neurohormonal blockade of an overly activated neurohormonal axis. No single marker has been able to predict or monitor HF with respect to disease progression, hospitalization, or mortality. New methods for diagnosis, monitoring therapy, and prognosis are warranted. Copeptin, a precursor of pre-provasopressin, is a new biomarker in HF with promising potential. Copeptin has been found to be elevated in both acute and chronic HF and is associated with prognosis. Copeptin, in combination with other biomarkers, could be a useful marker in the monitoring of disease severity and as a predictor of prognosis and survival in HF.

Copeptin as a biomarker in heart failure

Increased neurohormonal activation is a key feature of heart failure (HF). Copeptin is a surrogate marker for proarginine vasopressin and the prognostic value of copeptin has been reported for multiple disease states of both nonvascular and cardiovascular etiology. Elevated plasma copeptin in HF has been associated with adverse outcomes such as increased mortality, risk of hospitalization and correlates with the severity of HF. Copeptin may add prognostic information to already established predictors such as clinical variables and natriuretic peptides in HF. In addition, copeptin has been found to be a superior marker when compared with BNP and NT-proBNP in HF patients discharged after hospitalization caused by HF or myocardial infarction (MI). The optimal use of copeptin in HF remains unresolved and future appropriately sized and randomized trials must determine the role of copeptin in HF as a marker of adverse outcomes, risk stratification or as a target in biomarker-guided therapy with arginine vasopressin-antagonists in individualized patient treatment and everyday clinical practice.

Prediction of all-cause mortality with copeptin in cardio-cerebrovascular patients: A meta-analysis of prospective studies

BACKGROUND

Measurement of the biomarker copeptin may help identify disease severity and risk of mortality for a various diseases. This study sought to determine the relationship between copeptin and all-cause mortality of patients with cardio-cerebrovascular disease.

METHODS

Database of Medline and Web of Science were searched for studies with data involving the baseline copeptin levels and subsequent all-cause mortality outcomes. The pooled HRs of all-cause mortality were calculated and presented with 95%CIs. Subgroup analysis and sensitivity analysis were conducted to explore the possible sources of heterogeneity.

RESULTS

Data from 14,395 participants were derived from 28 prospective studies. Higher copeptin significantly increased the risk of all-cause mortality (per unit copeptin: HR=1.020, 95%CI=1.004-1.036; log unit copeptin: HR=2.884, 95%CI=1.844-4.512; categorical copeptin: HR=3.371, 95%CI=2.077-5.472). Subgroup analysis indicated that the risk of all-cause death was higher in cerebrovascular patients (per unit copeptin: HR=2.537, 95%CI=0.956-6.731; log unit copeptin: HR=3.419, 95%CI=2.391-4.888) than cardiovascular patients (per unit copeptin: HR=1.011, 95%CI=1.002-1.020; log unit copeptin: HR=2.009, 95%CI=1.119-3.608).

CONCLUSION

Copeptin is associated with all-cause mortality of patients with cardiovascular and cerebrovascular disease. Our study suggests that copeptin seems to be a promising novel biomarker for prediction of mortality in cardio-cerebrovascular patients, especially for cerebrovascular patients.

Emerging biomarkers in heart failure and cardiac cachexia

Biomarkers are objective tools with an important role for diagnosis, prognosis and therapy optimization in patients with heart failure (HF). To date, natriuretic peptides are closest to optimal biomarker standards for clinical implications in HF. Therefore, the efforts to identify and test new biomarkers in HF are reasonable and justified. Along the natural history of HF, cardiac cachexia may develop, and once at this stage, patient performance and prognosis is particularly poor. For these reasons, numerous biomarkers reflecting hormonal, inflammatory and oxidative stress pathways have been investigated, but only a few convey relevant information. The complex pathophysiology of HF appears far too complex to be embraced by a single biomarker; thus, a combined approach appears reasonable. With these considerations, we have reviewed the recent developments in the field to highlight key candidates with diagnostic, prognostic and therapy optimization properties, either alone or in combination.

Copeptin: a new marker in cardiology

Copeptin, the C-terminal part of the prohormone of vasopressin (AVP), is released together with AVP in stoichiometric concentrations reflecting an individual's stress level. Copeptin has come to be regarded as an important marker for identifying high-risk patients and predicting outcomes in a variety of diseases. It improves the clinical value of commonly used biomarkers and the tools of risk stratification. Elevated AVP activation and higher copeptin concentrations have been previously described in acute systemic disorders. However, the field that could benefit the most from the introduction of copeptin measurements into practice is that of cardiovascular disease. Determination of copeptin level emerges as a fast and reliable method for differential diagnosis, especially in acute coronary syndromes. A particular role in the diagnosis of acute myocardial infarction (AMI) is attributed to the combination of copeptin and troponin. According to available sources, such a combination allows AMI to be ruled out with very high sensitivity and negative predictive value. Moreover, elevated copeptin levels correlate with a worse prognosis and a higher risk of adverse events after AMI, especially in patients who develop heart failure. Some authors suggest that copeptin might be valuable in defining the moment of the introduction of treatment and its monitoring in high-risk patients. The introduction of copeptin into clinical practice might also provide a benefit on a larger scale by suggesting changes in the allocation of financial resources within the health system. Although very promising, further larger trials are required in order to assess the clinical benefits of copeptin in everyday practice and patient care.

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.