Use of natriuretic peptides to guide and monitor heart failure therapy

The inflammatory markers sST2, HSP27 and hsCRP as a prognostic biomarker panel in chronic heart failure patients

BACKGROUND

The inflammatory markers sST2, HSP27 and hsCRP have already been identified as prognostic markers in chronic heart failure (HF). Though individual biomarkers have proven their value in mortality risk prediction, the role of a multimarker strategy needs further evaluation.

MATERIALS AND METHODS

This is an exploratory reanalysis in chronic HF patients. Plasma HSP27, sST2 and hsCRP in outpatients with chronic HF were analysed. Patients were followed for a minimum of twelve months for the endpoint cardiovascular mortality and unplanned HF associated hospitalisation (=event). 15 year overall mortality was assessed retrospectively. The prognostic impact was assessed using a Cox proportional hazard model.

RESULTS

113 chronic HF patients were included. Median follow up time was 614 days and 37 patients (32.7%) experienced an event. A Kaplan-Meier analysis revealed that patients with increased sST2, HSP27 and hsCRP levels have significantly worse prognosis (p < 0.001). The use of a three-biomarker combination was superior in an independent risk prediction of an event (one high vs. two high: HR = 4.5, 95% CI: 1.3-15.5, p = 0.018; and one high vs. all high: HR = 9.8, 95% CI: 2.8-34.3, p < 0.001) as shown in a multivariable cox proportional hazard model. However, the biomarker panel did not predict 15 year overall mortality, in contrast to elevated HSP27 levels (p = 0.012).

CONCLUSIONS

The combination of all three markers is an independent predictor of cardiovascular death and unplanned HF associated hospitalisation but not overall mortality. Our findings suggest that adding those markers in combination to well established risk assessment parameters may improve risk stratification.

Venom natriuretic peptides guide the design of heart failure therapeutics

Heart failure (HF) affects over 26 million people world-wide. It is a syndrome triggered by loss of normal cardiac function due to many acute (eg myocardial infarction) and/or chronic (eg hypertension) causes and characterized by mixed beneficial and deleterious activation of a complex of multifaceted neurohormonal systems the net effect of which frequently is further adverse disruption of pressure-volume homeostasis. Unlike the situation in chronic heart failure, current strategies for treatment of acute heart failure are empirical and lack a strong evidence base. Management includes any of a combination of vasodilators, diuretics and ionotropic agents depending on the hemodynamic profile of the patient. Despite the improvement in the options available to improve outcomes in patients with chronic HF, for several decades little gain has been made in the treatment of the acute decompensated state. Morbidity and mortality rates remain high necessitating new therapeutic agents. The cardiac natriuretic peptides (NPs) are key hormones in pressure-volume homoeostasis. There are three isoforms of mammalian NPs, namely ANP, BNP and CNP. These peptides bind to membrane-bound NP receptors (NPRs) on the heart, vasculature and kidney to lower blood pressure and circulating volume. Intravenous infusion of NPs in HF patients improves hemodynamic status but is associated with occasional severe hypotension. Apart from mammalian NPs, snake venom NPs are an excellent source of pharmacologically distinct ligands that offer the possibility of engineering NPs for therapeutic purposes. Venom NPs have long half-lives, differential NPR activation profiles and varied NPR specificity. The scaffolds of venom NPs encode the molecular information for designing NPs with longer half-lives and improved and differential vascular and renal functions. This review focuses on the structure-function paradigm of mammalian and venom NPs and the different peptide engineering strategies that have been utilized in the design of clinically relevant new NP-analogues.

Evaluation of analytical performances using standardized analytical protocols and comparison of clinical results of the new ADVIA BNP and NT-proBNP immunoassays for the Centaur XPT platform

Background The study aim was to evaluate and compare analytical performances and clinical results of ADVIA BNP and PBNP methods using the Centaur XPT platform with those of Access BNP, using the DxI platform and the ECLIA NT-proBNP method, using the Cobas e411 platform, respectively. Methods Limits of blank (LoB), detection (LoD) and quantitation (LoQ) at 20% CV and 10% CV were evaluated according to international standardized protocols. The analytical parameters were assessed throughout a 90-working-day period using three curve calibrations. Results LoB, LoD and LoQ at 20% CV and 10% values of the ADVIA BNP method were 1.0 ng/L, 2.0 ng/L, 3.7 ng/L and 10.2 ng/L, respectively; while those of the ADVIA PBNP method were 1.3 ng/L, 3.0 ng/L, 9.7 ng/L and 22.3 ng/L, respectively. The ADVIA BNP and PBNP methods were able to measure the clinical decision values suggested by international guidelines for diagnosis of heart failure (HF) with an imprecision ≤6%. BNP concentrations measured with the ADVIA and Access methods showed a close linear regression (R=0.9923, n=200); a close linear regression was also found between NT-proBNP concentrations measured with the ADVIA and ECLIA methods (R=0.9954, n=202). However, the ADVIA method measured significantly lower BNP values than the Access method (on average -20.9%), while ADVIA PBNP method measured significantly higher NT-proBNP concentrations than the ECLIA method (on average +17.8%). Conclusions Analytical performances of the BNP and PBNP ADVIA methods are well in accordance with the quality specifications required by international guidelines for diagnosis and follow-up of patients with HF.

In-hospital worsening heart failure: a clinically relevant endpoint?

Outcome measures used for the clinical evaluation of patients with acute heart failure differ between studies and may neither adequately address the characteristic presenting symptoms and signs nor reflect the pathophysiological processes involved. In-hospital worsening of heart failure (WHF) is associated with poor outcomes and thus a potential endpoint conveying clinically meaningful prognostic information. Current definitions of WHF are based on the combination of worsening symptoms and signs and the intensification of treatment during admission. Definitions vary across studies and do not fully account for baseline therapy or circumstances in which there is failure to respond to treatment. Further, there are limited data to inform healthcare professionals as to which patients are most at risk of developing in-hospital WHF. In this opinion piece, we review the definitions for WHF used in recent and ongoing clinical trials and propose a novel definition, which captures failure to respond to treatment as well as clinical worsening (deterioration of symptoms and signs) of the patient's condition. Such a definition, applied consistently across studies, would help clarify the characteristics of patients likely to develop in-hospital WHF, allow comparative assessments of the effectiveness of interventions, and help guide appropriate patient management in order to improve outcomes.

Different trajectories and significance of B-type natriuretic peptide, congestion and acute kidney injury in patients with heart failure

The exact relationship existing among congestion status, brain natriuretic peptide (BNP) changes and acute kidney injury (AKI) has not been elucidated in patients with acute heart failure (AHF). The aims of this study are: to investigate the relation and prognostic role of BNP, AKI and clinical congestion after discharge; to define the exact BNP cut off value or a BNP in-hospital reduction to identify patients with higher risk during vulnerable post-discharge phase. We consecutively enrolled 157 patients with a diagnosis of AHF. BNP and creatinine were measured in all patients, and degree of failure was assessed. AKI was defined as a creatinine increase ≥0.3 mg/dL or eGFR reduction ≥20% during hospitalization. All patients were followed for 1 and 3 months. Of 146 included patients, 110 patients (75%) displayed effective decongestion, 116 (79%) showed a BNP decrease ≥30%, and 28 (19%) developed in-hospital AKI. BNP in-hospital decrease ≥30% was found more often in patients who showed good decongestion in comparison to patients in persistent failure (63 vs 22%; p < 0.001). The ROC curve analyses at 3 months show that both BNP reduction of 30% between admission and discharge and decongestion at discharge identifies patients with a reduced incidence of cardiovascular events (AUC = 0.79, confidence interval 0.68-0.90, sensibility 90%, sensitivity 50% p < 0.001). Kaplan-Meier survival plots show a better outcome in patients with a BNP decrease ≥30% and good decongestion at discharge (p = 0.03). BNP reduction in AHF is associated with decongestion. BNP reduction associated with decongestion at discharge is a favorable prognostic indicator at 90-day survival irrespective of the AKI occurrence.

Evaluation of red blood cell distribution width as a prognostic indicator in cats with acquired heart disease, with and without congestive heart failure

Objectives Congestive heart failure secondary to cardiomyopathy is a common manifestation of cardiac disease in cats, carrying a variable prognosis. The objective of this retrospective study was to evaluate the relationship between red blood cell distribution width (RDW) and survival time in feline patients with acquired heart disease with and without congestive heart failure (CHF). Methods Three hundred and forty-nine client-owned cats with echocardiograms and complete blood count, including RDW measurement, performed between March 2006 and December 2011, were included in the study. Patient characteristics, including signalment, hematocrit, RDW, echocardiographic parameters and survival, were recorded. Comparisons between RDW in cats with asymptomatic acquired heart disease and those with CHF were made. Survival was documented and compared at 30 days and 6 months. Results CHF was present in 80 cats and absent in 269 cats. Cats with CHF had an increase in mortality compared with cats without CHF at 30 days and 6 months ( P = 0.007 and P = 0.04, respectively). RDW was not significantly associated with survival in cats with or without CHF at 30 days or 6 months. A significant difference was found between median RDW values in cats with CHF vs cats without CHF (16.3% vs 15.8%; P = 0.02). The median RDW value was significantly higher in cats with unclassified cardiomyopathy compared with cats with other types of cardiomyopathy (16.3% vs 15.8%; P = 0.03). Conclusions and relevance Single RDW values did not predict mortality in cats with acquired heart disease but may be useful in determining if cats have decompensated heart disease and CHF. Human studies indicate that incremental increases in serial RDW measurements are associated with decreased survival; serial RDW measurements in cats may be an area of future study.

Association between Survival Time and Changes in NT-proBNP in Cats Treated for Congestive Heart Failure

Background

Reductions in N‐terminal pro‐B‐type natriuretic peptide (NT‐proBNP) concentrations after treatment have been associated with improved survival in people with congestive heart failure (CHF), but have not been reported in cats with CHF.

Objectives

To evaluate changes in NT‐proBNP concentrations in cats with CHF after treatment and determine whether serial NT‐proBNP measurements provide prognostic information.

Animals

Thirty‐one client‐owned cats.

Methods

Prospective, observational study in cats with new onset CHF secondary to cardiomyopathy. Concentrations of NT‐proBNP were measured within 4 hours of admission to the hospital, on the day of discharge, and at re‐evaluation 7–10 days later.

Results

Median NT‐proBNP concentrations decreased significantly from admission (1,713 pmol/L [range, 160–3,784 pmol/L]) to discharge (902 pmol/L [range, 147–3,223 pmol/L]); P = .005) and from admission to re‐evaluation (1,124 pmol/L [range, 111–2,727 pmol/L]; P = .024). Median survival time was 109 days (range, 1–709 days), with 5 cats still alive at the time of analysis. Cats with a larger percent decrease in NT‐proBNP from admission to discharge had a longer survival time (P = .048). Cats with evidence of active CHF at the time of re‐evaluation (P = .010) and cats whose owners had difficulty administering medications (P = .045) had shorter survival times.

Conclusions and clinical importance

Cats with a larger percent decrease in NT‐proBNP during hospitalization and no evidence of CHF at the time of re‐evaluation had longer survival times. Additional studies are needed to determine whether NT‐proBNP can help guide treatment in cats with CHF.

Effects of carvedilol on structural and functional outcomes and plasma biomarkers in the mouse transverse aortic constriction heart failure model

INTRODUCTION

Despite the widespread use of the mouse transverse aortic constriction heart failure model, there are no reports on the characterization of the standard-of-care agent carvedilol in this model.

METHODS

Left ventricular pressure overload was produced in mice by transverse aortic constriction between the innominate and left common carotid arteries. Carvedilol was administered at multiple dose levels (3, 10 and 30 mg/kg/day per os; yielding end-study mean plasma concentrations of 0.002, 0.015 and 0.044 µM, respectively) in a therapeutic design protocol with treatment initiated after the manifestation of left ventricular remodeling at 3 weeks post transverse aortic constriction and continued for 10 weeks.

RESULTS

Carvedilol treatment in transverse aortic constriction mice significantly decreased heart rate and left ventricular dP/dt (max) at all dose levels consistent with β-adrenoceptor blockade. The middle dose of carvedilol significantly decreased left ventricular weight, whereas the higher dose decreased total heart, left and right ventricular weight and wet lung weight compared to untreated transverse aortic constriction mice. The higher dose of carvedilol significantly increased cardiac performance as measured by ejection fraction and fractional shortening and decreased left ventricular end systolic volume consistent with the beneficial effect on cardiac function. End-study plasma sST-2 and Gal-3 levels did not differ among sham, transverse aortic constriction control and transverse aortic constriction carvedilol groups. Plasma brain natriuretic peptide concentrations were elevated significantly in transverse aortic constriction control animals (~150%) compared to shams in association with changes in ejection fraction and heart weight and tended to decrease (~30%, p = 0.10-0.12) with the mid- and high-dose carvedilol treatment.

CONCLUSION

A comparison of carvedilol hemodynamic and structural effects in the mouse transverse aortic constriction model versus clinical use indicates a strong agreement in effect profiles preclinical versus clinical, providing important translational validation for this widely used animal model. The present plasma brain natriuretic peptide biomarker findings support the measurement of plasma natriuretic peptides in the mouse transverse aortic constriction model to extend the translational utility of the model.

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.

Targeting N-Terminal Pro-Brain Natriuretic Peptide in Older Versus Younger Acute Decompensated Heart Failure Patients

OBJECTIVES

The aim of this study was to analyze the prognostic value and attainability of N-terminal pro-brain natriuretic peptide (NT-proBNP) levels in young and elderly acute decompensated heart failure (ADHF) patients.

BACKGROUND

Less-effective NT-proBNP-guided therapy in chronic heart failure (HF) has been reported in elderly patients. Whether this can be attributed to differences in prognostic value of NT-proBNP or to differences in attaining a prognostic value is unclear. The authors studied this question in ADHF patients.

METHODS

Our study population comprised 7 ADHF cohorts. We defined absolute (<1,500 ng/l, <3,000 ng/l, <5,000 ng/l, and <15,000 ng/l) and relative NT-proBNP discharge cut-off levels (>30%, >50%, and >70%). Six-month all-cause mortality after discharge was studied for each level in Cox regression analyses, and compared between elderly (age >75 years) and young patients (age ≤75 years). Thereafter, we compared percentages of elderly and young patients attaining NT-proBNP levels (= attainability).

RESULTS

A total of 1,235 patients (59% male, 45% >75 years of age) was studied. Admission levels of NT-proBNP were significantly higher in elderly versus younger patients. The prognostic value of absolute and relative NT-proBNP levels was similar in elderly and young patients. Attainability was significantly lower in elderly patients for all absolute levels and a >50% relative reduction, but not for >30% and >70%. For absolute levels, attainability differences between age groups were decreased to a large extent after correction for admission NT-proBNP and anemia at discharge. For relative levels, attainability differences disappeared after correction for HF etiology and anemia at discharge.

CONCLUSIONS

In young and elderly ADHF patients, it is not the prognostic value of absolute and relative NT-proBNP levels that is different, but the attainability of these levels that is lower in the elderly. This can largely be attributed to factors other than age.

Soluble Glycoprotein 130 and Heat Shock Protein 27 as Novel Candidate Biomarkers of Chronic Heart Failure with Preserved Ejection Fraction

BACKGROUND

Despite their importance, the current clinical biomarkers of chronic heart failure have limitations. In this study, soluble glycoprotein 130 (sgp130), heat shock protein 27 (hsp27), dipeptidyl peptidase IV (dpp4) and cathepsin S (CTSS) were tested for their potential as novel biomarkers for diagnosing chronic heart failure (CHF) with preserved ejection fraction.

METHODS

We compared the circulating levels of sgp130, hsp27, dpp4, and cathepsin S in patients with CHF with preserved ejection fraction (n=50) and in controls (n=50), determined how well these candidate biomarkers distinguish patients with CHF from controls, and assessed whether these candidates are superior to N-terminal pro brain natriuretic peptide (NT-pro-BNP) as diagnostic tools.

RESULTS

After adjusting for clinical covariates, patients with CHF showed significantly higher mean concentrations of sgp130 (317.38pg/ml vs. 215.90 pg/ml), hsp27 (2601.02 pg/ml vs. 923.61 pg/ml) and NT-pro-BNP (982.35 pg/ml vs. 331.99 pg/ml), but not dpp4 (6930.9 4pg/ml vs. 7081.37 pg/ml) or CTSS (1050.46 pg/ml vs. 984.96 pg/ml), than did controls. In the receiver operating characteristic curve analysis, hsp27 showed the most notable difference between CHF patients and controls, with the largest area under the curve (AUC) (0.920); the AUC values for sgp130 and NT-pro-BNP were 0.877 and 0.882, respectively.

CONCLUSIONS

Soluble glycoprotein 130 and hsp27 are novel candidate biomarkers for diagnosing CHF with preserved ejection fraction and thus warrant further investigation; neither dpp4 nor CTSS showed promise as biomarkers of CHF.

Biomarkers in heart failure: the importance of inconvenient details

The proliferation of cardiac-related biomarkers and advocacy for their use has often come without adequate discussion of limitations in the interpretation of values and their best use in heart failure (HF) patients to provide a balanced assessment of how cardiac biomarkers are advocated for use in HF and areas where we would argue there are no gaps in knowledge. We include suggestions to address these issues. We have focused on peer-reviewed publications over the period 2000 to present. Most studies have used samples at one or at most two points in time to define risk. Although biomarkers might add to the magnitude of risk, it is unclear how often they lead to changes in treatment. We suggest that defining the use of serial biomarker testing over time would be more helpful. To do this, it is necessary to take into account the biomarker's analytical and biological variability in addition to its ability to define and monitor therapy. These factors are often overlooked leading to conclusions that may be statistically significant but not clinically or analytically robust. An appreciation of the value and limitations of biomarker use is important to all clinicians who manage HF patients. If the proper studies are done so that biomarkers are used optimally, they will likely be helpful in defining when and how to intervene. If we continue as we have, we will continue to have ambiguity about the use of these valuable probes in the assessment and management of HF.

State of the art of immunoassay methods for B-type natriuretic peptides: An update

The aim of this review article is to give an update on the state of the art of the immunoassay methods for the measurement of B-type natriuretic peptide (BNP) and its related peptides. Using chromatographic procedures, several studies reported an increasing number of circulating peptides related to BNP in human plasma of patients with heart failure. These peptides may have reduced or even no biological activity. Furthermore, other studies have suggested that, using immunoassays that are considered specific for BNP, the precursor of the peptide hormone, proBNP, constitutes a major portion of the peptide measured in plasma of patients with heart failure. Because BNP immunoassay methods show large (up to 50%) systematic differences in values, the use of identical decision values for all immunoassay methods, as suggested by the most recent international guidelines, seems unreasonable. Since proBNP significantly cross-reacts with all commercial immunoassay methods considered specific for BNP, manufacturers should test and clearly declare the degree of cross-reactivity of glycosylated and non-glycosylated proBNP in their BNP immunoassay methods. Clinicians should take into account that there are large systematic differences between methods when they compare results from different laboratories that use different BNP immunoassays. On the other hand, clinical laboratories should take part in external quality assessment (EQA) programs to evaluate the bias of their method in comparison to other BNP methods. Finally, the authors believe that the development of more specific methods for the active peptide, BNP1-32, should reduce the systematic differences between methods and result in better harmonization of results.

NT-proBNP, blood pressure, and cognitive decline in the oldest old: The Leiden 85-plus Study

OBJECTIVE

To study the relation between N-terminal pro-brain natriuretic peptide (NT-proBNP) levels, used as a marker of heart failure in clinical practice, blood pressure (BP), and cognitive decline in the oldest old.

METHODS

In 560 participants of the Leiden 85-plus Study, we measured NT-proBNP levels and BP at age 85 years, at baseline, and global cognitive function (Mini-Mental State Examination [MMSE]) annually during the follow-up of 5 years.

RESULTS

Subjects in the highest tertile of NT-proBNP levels scored 1.7 points lower on the MMSE at age 85 years than subjects in the lowest tertile (p = 0.004), and had a 0.24-point-steeper decline in MMSE score per year (p = 0.021). The longitudinal association disappeared after full adjustment for possible confounders (0.14-point-steeper decline, p = 0.187). Subjects in the category "highest tertile of NT-proBNP and the lowest tertile of systolic BP" had a 3.7-point-lower MMSE score at baseline (p < 0.001) and a 0.49-point-steeper decline in MMSE score per year (p < 0.001) compared with subjects in the other categories.

CONCLUSIONS

In the oldest old, high NT-proBNP levels are associated with lower MMSE scores. The combination of high NT-proBNP levels and low systolic BP is associated with worst global cognitive function and the steepest cognitive decline. Possibly, a failing pump function of the heart results in lower BP and lower brain perfusion with resultant brain dysfunction.

Single measurement of serum N-terminal pro-brain natriuretic peptide: the best predictor of long-term mortality in patients with chronic systolic heart failure

BACKGROUND

Although high serum natriuretic peptide (NP) has long been associated with mortality prediction, it was usually tested under acute heart failure (HF) conditions and periods of analysis were short. This may explain the lack of consensus when its routine measurement for mortality prediction is contemplated. Here we evaluated, at the first clinic visit of chronic systolic HF patients, the usefulness of a single serum NP assessment for long-term mortality prediction.

METHODS

In 279 consecutive patients with chronic systolic HF, serum NT-proBNP was routinely measured once during the first clinic visit. We analyzed correlations between recorded mortality and the NT-proBNP finding, along with several known clinical echocardiographic, electrocardiographic and laboratory parameters recorded at that visit.

RESULTS

During average follow-up of 34±21months 59 (21%) patients died. Serum NT-proBNP was the strongest of the tested predictors of mortality [hazard ratio 3.76, 95% Cl (1.20-11.80), p=0.008]. Nearly seven years later, mortality was still higher in patients with higher initial serum NT-proBNP (p<0.001).

CONCLUSIONS

Compared to many other traditional prognostic parameters tested at the same time, the single serum NT-proBNP finding was the strongest predictor of long-term mortality. These results may justify its routine use for this purpose.

Natriuretic peptides modulate ATP-sensitive K(+) channels in rat ventricular cardiomyocytes

B-type natriuretic peptide (BNP) and C-type natriuretic peptide (CNP), and (Cys-18)-atrial natriuretic factor (4–23) amide (C-ANF), are cytoprotective under conditions of ischemia–reperfusion, limiting infarct size. ATP-sensitive K⁺ channel (K_ATP) opening is also cardioprotective, and although the K_ATP activation is implicated in the regulation of cardiac natriuretic peptide release, no studies have directly examined the effects of natriuretic peptides on cardiac K_ATP activity. Normoxic cardiomyocytes were patch clamped in the cell-attached configuration to examine sarcolemmal K_ATP (sK_ATP) activity. The K_ATP opener pinacidil (200 μM) increased the open probability of the patch (NPo; values normalized to control) at least twofold above basal value, and this effect was abolished by HMR1098 10 μM, a selective K_ATP blocker (5.23 ± 1.20 versus 0.89 ± 0.18; P < 0.001). We then examined the effects of BNP, CNP, C-ANF and 8Br-cGMP on the sK_ATP current. Bath application of BNP (≥10 nM) or CNP (≥0.01 nM) suppressed basal NPo (BNP: 1.00 versus 0.56 ± 0.09 at 10 nM, P < 0.001; CNP: 1.0 versus 0.45 ± 0.16, at 0.01 nM, P < 0.05) and also abolished the pinacidil-activated current at concentrations ≥10 nM. C-ANF (≥10 nM) enhanced K_ATP activity (1.00 versus 3.85 ± 1.13, at 100 nM, P < 0.05). The cGMP analog 8Br-cGMP 10 nM dampened the pinacidil-activated current (2.92 ± 0.60 versus 1.53 ± 0.32; P < 0.05). Natriuretic peptides modulate sK_ATP current in ventricular cardiomyocytes. This may be at least partially associated with their ability to augment intracellular cGMP concentrations via NPR-A/B, or their ability to bind NPR-C with high affinity. Although the mechanism of modulation requires elucidation, these preliminary data give new insights into the relationship between natriuretic peptide signaling and sK_ATP in the myocardium.

A His6-SUMO-eXact tag for producing human prepro-urocortin 2 in Escherichia coli for raising monoclonal antibodies

This is a first report of recombinant production of human prepro-Urocortin 2 in Escherichia coli by N-terminal fusion with a triple His₆-SUMO-eXact tag and its subsequent use as an antigen for the production and screening of very high affinity monoclonal antibodies. The rationale for this combinatorial construct is that the His tag allows first step protein purification of insoluble and soluble proteins, the SUMO tag enhances protein expression level and solubility, while the eXact tag facilitates anion-triggered on-column cleavage of the triple tag to recover pure native proteins in a simple two-step protein purification procedure. Compared with an eXact fusion alone, the presence of the SUMO moiety enhanced overall expression levels by 4 to 10 fold but not the solubility of the highly basic prepro-Urocortin 2. Insoluble SUMO-eXact-preproUCN2 was purified in milligram quantities by denaturing IMAC and solubilized in native phosphate buffer by on-column refolding or step-wise dialysis. Only a small fraction of this solubilized protein was able to bind onto the eXact™ affinity column and cleaved by NaF treatment. To test whether binding and cleavage failure was due to improperly refolded SUMO-eXact-preproUCN2 or to the presence of N- and C-terminal sequences flanking the eXact moiety, we created a SUMO-eXact-thioredoxin construct which was overexpressed mainly in the soluble form. This protein bound to and was cleaved efficiently on the eXact™ column to yield native thioredoxin. Solubilized SUMO-eXact-preproUCN2 was used successfully to generate two high affinity mouse monoclonal antibodies (KD~10⁻¹⁰ and 10⁻¹¹ M) specific to the pro-region of Urocortin 2.

Heart failure biomarkers

Biomarker testing in patients with heart failure (HF) is rapidly expanding. With high-quality research indicating its diagnostic and prognostic capabilities, biomarkers are excellent adjuncts to manage patients with HF. Their superiority lies mainly in their reflection of ongoing pathophysiological events at a cellular level. Monitoring biomarker levels has been shown to provide incremental information on the progression of disease, thus allowing to better tailor treatment and management. Several biomarkers have gained attention in the past decade and continuing research demonstrates the specificity of each biomarker to be used on its own or in combination to improve diagnostic accuracy. This review will provide an insight into the role of such biomarkers, which are widely studied in the setting of HF so as to delineate their role in diagnosing, prognosticating, and titrating HF therapy.