Brain natriuretic peptide is stable in whole blood and can be measured using a simple rapid assay: implications for clinical practice

Analytical performance of a single epitope B-type natriuretic peptide sandwich immunoassay on the Minicare platform for point-of-care diagnostics

Point-of-care B-type natriuretic peptide (BNP) testing with adequate analytical performance has the potential to improve patient flow and provide primary care givers with easy-to-use advanced diagnostic tools in the management of heart failure. We present the analytical evaluation of the Minicare BNP immunoassay under development on the Minicare I-20 platform for point-of-care testing. Analytical performance was evaluated using EDTA venous whole blood, EDTA plasma and capillary whole blood. Method comparison with a lab-testing system was performed using samples from 187 patients. Normal values were determined based on 160 healthy adults, aging from 19 to 70 years. Limit of blank (LoB), limit of detection (LoD) were determined to be 3.3 ng/L, 5.8 ng/L. Limit of quantitation (LoQ) in whole blood at 20% and 10% coefficient of variation (CV) was found < 9 ng/L and <30 ng/L respectively without significant differences between EDTA whole blood and EDTA plasma. Total CV was found to be from 6.7% to 9.7% for BNP concentrations between 92.6 and 3984 ng/L. The sample type comparison study demonstrated correlation coefficients between 0.97 and 0.99 with slopes between 1.03 and 1.09 between the different samples. Method comparison between Minicare BNP and Siemens ADVIA Centaur BNP demonstrated a correlation coefficient of 0.92 with a slope of 1.06. The 97.5% URL of a healthy population was calculated to be 72.6 ng/L. The Minicare BNP assay is a robust, easy-to-use and sensitive test for rapid determination of BNP concentrations that can be used in a near-patient setting.

Novel markers and therapies for patients with acute heart failure and renal dysfunction

BACKGROUND

Acute kidney injury complicates decompensated heart failure in ∼33% of cases and is associated with morbidity and mortality; thus, we sought to systematically review this topic in order to summarize novel diagnostic and therapeutic approaches.

METHODS

Structured PubMed searches on these topics were conducted in February 2014 and relevant literature was identified. The PubMed search identified a total of 192 articles that were individually screened for inclusion in this analysis, and 58 were included.

RESULTS

Acute kidney injury, defined by substantial increases in serum creatinine, is associated consistently with prolonged length of stay, rehospitalization, and mortality. Biomarker studies suggested that natriuretic peptides are prognostic for shorter- and longer-term mortality. Novel proteins indicating kidney damage and albumin in the urine are associated with acute kidney injury. The most promising acute pharmacologic treatment appears to be serelaxin, which has been shown to improve acute heart failure symptoms, hemodynamic parameters, and renal function.

CONCLUSIONS

The presence of acute kidney injury results in worse clinical outcomes for patients with acute heart failure. Novel biomarkers and therapies hold the promise of improving both cardiac and renal outcomes in these patients.

The in vitro stability of novel cardiovascular and sepsis biomarkers at ambient temperature

BACKGROUND

The in vitro stability of a biomarker can determine whether it should be used in clinical practice where long delays between sampling and assay are common. We measured the in vitro stability of five novel biomarkers that are being evaluated for their diagnostic and/or prognostic utility in patients with heart failure: mid-regional pro-atrial natriuretic peptide (MR-proANP), mid-regional pro-adreno-medullin (MR-proADM), C-terminal pro-endothelin-1 (CT-proET-1), C-terminal pro-arginine vasopressin (copeptin) and ultrasensitive procalcitonin (PCT).

METHODS

Peripheral venous blood samples were obtained from 19 patients with chronic heart failure into four EDTA tubes. The first tubes were centrifuged immediately at 4°C with the other tubes stored at 20°C for 4, 24 or 72 hours (h) before centrifuging. Supernatant plasma was frozen and stored at -80°C until assay. The levels of analyte in samples processed with and without delay were compared using correlation analysis, paired t-tests and Bland-Altman plots.

RESULTS

Copeptin and PCT were stable up to 72 h at 20°C in whole blood and MR-proANP and MR-proADM up to 24 h. However, CT-proET-1 showed some signs of degradation after only 4 h with 94% of analyte recovered after 24 h, dropping to 80% after 72 h.

CONCLUSIONS

MR-proANP, MR-proADM, copeptin and PCT are stable biomarkers and therefore suitable for introduction into routine clinical practice in a primary or secondary care setting where delays in sample preparation and assay are likely. Ideally, samples for measurement of CT-proET-1 should be centrifuged soon after venepuncture but the analyte is stable enough for most routine clinical purposes.

The prognostic value of anemia, right-heart catheterization and neurohormones in chronic heart failure

Chronic heart failure is increasing in incidence and prevalence. Recent advances in medical therapy have improved prognosis such that, even in patients with chronic heart failure who are New York Heart Association Classes III and IV, annual mortality can be as low as 11.4%. Nevertheless, some patients remain at risk, despite optimal disease-modifying medical therapy, and it would seem appropriate that these patients are considered first for appropriate device therapy or for the scarce resource of cardiac transplantation. Many parameters have been assessed for their prognostic potential in patients with chronic heart failure. In this review, pertinent studies investigating anemia, right-heart hemodynamics and neurohormones as prognostic markers are discussed.

Novel Immunoassay for Quantification of Brain Natriuretic Peptide and Its Precursor in Human Blood

Background: Brain natriuretic peptide (BNP) is an unstable molecule that can rapidly lose immunologic activity in blood. Conventional sandwich BNP immunoassays use 2 antibodies specific to 2 different epitopes. Larger distances between epitopes are associated with a greater probability of proteolysis sites being located between the antibody-binding sites, and thus such assays have an increased susceptibility to underdetect BNP because of the increased likelihood of proteolytic degradation. The purpose of our study was to develop a sandwich immunoassay for the precise quantification of BNP and BNP precursor (proBNP) in human blood that is not susceptible to proteolysis.

Methods: Mice were immunized with an immune complex consisting of monoclonal antibody (MAb) 24C5 (specific for BNP peptide 11–22) and the entire BNP molecule. The MAb used in our assay (Ab-BNP2) recognizes the immune complex but neither free BNP nor MAb 24C5.

Results: We used MAbs 24C5 and Ab-BNP2 to develop a new type of sandwich BNP assay (the “single-epitope sandwich assay”), which requires only a short BNP fragment (fragment 11–22) for immunodetection. This assay recognizes both BNP and proBNP with the same efficiency and sensitivity and demonstrates both considerably less susceptibility to antigen degradation and greater stability of the measured antigen than conventional sandwich BNP immunoassays.

Conclusions: We have developed this sensitive single-epitope sandwich assay for detecting BNP, proBNP, and their fragments in human blood. This assay appears promising for use in clinical studies to assist in triage, management, and outcomes assessment in heart failure patients.

Relationship between Serum N-Terminal Pro-Brain Natriuretic Peptide Level and Left Ventricular Dysfunction and Extracellular Water in Continuous Ambulatory Peritoneal Dialysis Patients

This study inquired the relationship between serum N-terminal pro-brain natriuretic peptide (NT-proBNP) levels and left ventricular (LV) dysfunction and extracellular water in continuous ambulatory peritoneal dialysis (CAPD) patients. We conducted a cross-sectional study of 30 CAPD patients. Each patient was admitted to the department of internal medicine, Chosun University Hospital between February and October, 2006. Echocardiography was performed using HDI 5000, allowing M-mode, two-dimensional measurement. A multifrequency bioimpedance analyzer was used; extracellular water was calculated as a percentage of total body water and was understood as the index of volume load of CAPD patients. The mean age was 47±12 years. Underlying causes of renal failure were 14 with diabetes mellitus, 7 with hypertension, and 9 with chronic glomerulonephritis. The mean serum NT-proBNP level was 14236.56 (83-35,000) pg/mL. LV mass index and LV ejection fraction were 151.67±42.5 g/m² and 57.48±12.9%, respectively. The mean extracellular water was 35.97±1.04%. Serum NT-proBNP levels correlated positively with LV mass index (r=0.768, p=0.01) and extracellular water (r=0.866, p=0.01) and negatively with LV ejection fraction (r=-0.808, p=0.01). Serum NT-proBNP levels significantly correlated with LV mass index, LV ejection fraction, and extracellular water. Therefore, serum NT-proBNP levels can be a clinical predictive marker for LV hypertrophy, LV dysfunction, and volume status in CAPD patients.

Relationship between Plasma B-type Natriuretic Peptide and Ventricular Function in Adult Cardiac Surgery Patients

Plasma concentrations of B-type natriuretic peptide (BNP) were analysed during the peri- and post-operative periods in cardiac surgery patients, and the relationship between plasma BNP concentrations and various clinical parameters was explored. Thirty patients (17 women, 13 men) of age 54.5 ± 17.1 years undergoing cardiac surgery between June 2004 and March 2005 were enrolled. Plasma BNP concentrations were measured pre-operatively, immediately post-operatively, and on the first, second, fourth and seventh post-operative days. On the first post-operative day, the BNP level was significantly increased but levels returned to baseline values by the seventh post-operative day. The pre-operative BNP level correlated with left ventricular ejection fraction and age, and the level 24 h after surgery correlated with left ventricular end-diastolic dimension and pre-operative BNP levels. These results showed that the plasma BNP concentration becomes markedly and acutely elevated after cardiac surgery, reflecting temporary ventricular dysfunction.

Concentrations of brain natriuretic peptide in the plasma predicts outcomes of treatment of children with decompensated heart failure admitted to the Intensive Care unit

OBJECTIVES

It is known that levels of brain natriuretic peptide predict outcomes of treatment for adults with decompensated heart failure. We hypothesized that it could predict outcomes in children with this condition.

METHODS

We divided retrospectively 82 patients with serial measurements of brain natriuretic peptide into 3 groups: those who survived and did not need readmission within less than 60 days; those who survived but needed readmission within less than 60 days; and those who died in hospital or within less than 60 days. Initial and final levels of the peptide correlated with adverse outcomes.

RESULTS

The percent change in level of the peptide was minus 78 percent, minus 38 percent, and 138 percent in the readmission-free group, the readmitted, and nonsurviving groups, respectively. Final levels were significantly lower in the readmission-free group than in the readmitted and nonsurviving groups (p equals 0.013 and p is less than 0.00001, respectively) and in the readmitted group than in the nonsurvivors (p equals 0.013). On univariate analysis, the final level, the change in level, and the percentage change in level significantly predicted outcomes (p equals 0.0002, 0.0072 and 0.0005, respectively). On multivariate analysis, only the final level of the peptide significantly predicted outcomes (p equals 0.01).

CONCLUSIONS

A final level of brain natriuretic peptide of greater than or equal to 760 picograms per millilitre strongly predicted an adverse outcome. Patients with higher final levels may be at higher risk of death and readmission, suggesting that this variable effectively predicts the response to treatment and prognosis in children with heart failure.

Prognostic Value of B-Type Natriuretic Peptides in Patients With Stable Coronary Artery Disease

OBJECTIVES

The purpose of this study was to assess the association between B-type natriuretic peptide (BNP) and N-terminal pro-B-type natriuretic peptide (NT-proBNP) and the incidence of specific cardiovascular events in low-risk patients with stable coronary disease, the incremental prognostic information obtained from these two biomarkers compared with traditional risk factors, and their ability to identify patients who may benefit from angiotensin-converting enzyme (ACE) inhibition.

BACKGROUND

The prognostic value of BNPs in low-risk patients with stable coronary artery disease remains unclear.

METHODS

Baseline plasma BNP and NT-proBNP concentrations were measured in 3,761 patients with stable coronary artery disease and preserved left ventricular function participating in the PEACE (Prevention of Events With Angiotensin-Converting Enzyme Inhibition) study, a placebo-controlled trial of trandolapril. Multivariable Cox regression was used to assess the association between natriuretic peptide concentrations and the incidence of cardiovascular mortality, fatal or nonfatal myocardial infarction, heart failure, and stroke.

RESULTS

The BNP and NT-proBNP levels were strongly related to the incidence of cardiovascular mortality, heart failure, and stroke but not to myocardial infarction. In multivariable models, BNP remained associated with increased risk of heart failure, whereas NT-proBNP remained associated with increased risk of cardiovascular mortality, heart failure, and stroke. By C-statistic calculations, BNP and NT-proBNP significantly improved the predictive accuracy of the best available model for incident heart failure, and NT-proBNP also improved the model for cardiovascular death. The magnitude of effect of ACE inhibition on the likelihood of experiencing cardiovascular end points was similar, regardless of either BNP or NT-proBNP baseline concentrations.

CONCLUSIONS

In low-risk patients with stable coronary artery disease and preserved ventricular function, BNPs provide strong and incremental prognostic information to traditional risk factors.

The diagnostic accuracy and utility of a B-type natriuretic peptide test in a community population of patients with suspected heart failure

BACKGROUND

National guidelines suggest the use of natriuretic peptides in suspected heart failure but there have been no studies comparing assays in primary care.

AIM

To test and compare the diagnostic accuracy and utility of B-type natriuretic peptide (BNP) and N-terminal B-type natriuretic peptide (NT proBNP) in diagnosing heart failure due to left ventricular systolic dysfunction in patients with suspected heart failure referred by GPs to one-stop diagnostic clinics.

DESIGN OF STUDY

Community cohort, prospective, diagnostic accuracy study.

SETTING

One-stop diagnostic clinics in Darlington Memorial and Bishop Auckland General Hospitals and general practices in South Durham.

SUBJECTS

Two hundred and ninety-seven consecutive patients with symptoms and signs suggestive of heart failure referred from general practice.

METHOD

The study measured sensitivity, specificity, positive and negative predictive values (PPV, NPV), and area under receiver operating characteristic curve for BNP (near patient assay) and NT proBNP (laboratory assay) in diagnosis of heart failure due to left ventricular systolic dysfunction. The NPV of both assays was determined as a potential method of reducing the number of referrals for echocardiography.

RESULTS

One hundred and fourteen of the 297 patients had left ventricular systolic dysfunction (38%). At the manufacturer's recommended cut-off of 100 pg/ml BNP gave a NPV of 82%. BNP performed better at a cut-off of 40 pg/ml with a NPV of 88%. At a cut-off of 150 pg/ml, NT proBNP gave a NPV of 92%. Using cut-offs of 40 pg/ml and 150 pg/ml for BNP and NT pro-BNP, respectively, could have prevented 24% and 25% of referrals to the clinic, respectively.

CONCLUSIONS

In this setting, NT pro-BNP performed marginally better than BNP, and would be easier to use practically in primary care. A satisfactory cut-off has been identified, which needs validating in general practice. NT pro-BNP could be used to select referrals to a heart failure clinic or for echocardiography. This process needs testing in real-life general practice.

Elevated levels of natriuretic peptides in patients with pulmonary thromboembolism

BACKGROUND

Pulmonary thromboembolism (PTE) occurs in a wide variety of clinical settings and presents a diagnostic challenge to clinicians, often requiring extensive imaging of the vascular bed. Management increasingly requires accurate risk stratification to rapidly identify those with massive and submassive PTE requiring different therapeutic strategies such as thrombolysis. Provision of a rapid blood test that improves diagnostic certainty and helps stratify risk could therefore bridge the gap between uncertainty and delivery of immediate early life-saving treatment.

METHODS AND RESULTS

One hundred and fourteen consecutive patients with suspected PTE underwent prospective evaluation. Venous blood samples were obtained from an unselected group referred for ventilation-perfusion scintigraphy. B-type natriuretic peptide (BNP), atrial natriuretic peptide (ANP) and N-terminal pro-ANP (N-ANP) were measured by radioimmunoassay using commercially available kits. The scans were classified into three groups according to standard criteria (PIOPED); normal scan (N) (n=20), low/intermediate probability (L/I) of PTE (n=77) and high probability (H) of PTE (n=17). Comparisons were also made between patients with high probability scans who died (n=3) and those who survived (n=14). Values are quoted for the median and interquartile ranges. There were statistically significant differences between groups for levels of (a) BNP (P<0.001): N=6.7 pmol/l (5.6-11.9), L/I=12.5 pmol/l (6.7-28.2) and H=18.5 pmol/l (12.6-74.6); (b) ANP (P<0.005): N=12.6 pmol/l (7.1-16.0), L/I=19.51 pmol/l (12.5-28.2) and H=19.1 pmol/l (15.7-31.7) and (c) N-ANP (P<0.05): N=177 pmol/l (119-200), L/I=302 pmol/l (152-576) and H=322 pmol/l (223-563). Levels of BNP and ANP were significantly (P<0.05) higher in patients with high probability scans and a diagnosis of PTE who died (n=3) than in those who survived (n=14); BNP: 91.6 pmol/l (77.5-336.2) vs. 14.4 pmol/l (11.9-27.4) and ANP 32.5 pmol/l (21.7-105.5) vs. 17.6 pmol/l (15.2-19.3), respectively.

CONCLUSIONS

PTE is associated with significantly elevated levels of the natriuretic peptides ANP, BNP and N-ANP. Increasing ventilation-perfusion mismatch on scintigraphy corresponds to incremental increases in the levels of ANP, BNP and N-ANP found. These peptides, and in particular BNP, may add to the diagnosis by rapidly providing a probability of PE before dedicated imaging studies can be performed. Natriuretic peptides require further study to establish their role in identifying a high-risk group who may benefit from early treatments such as thrombolysis.

Diagnostic and Prognostic Performance of N-Terminal ProBNP in Primary Care Patients With Suspected Heart Failure

BACKGROUND

The value of N-terminal pro-brain natriuretic peptide (NT-proBNP) in terms of diagnosis and prognosis in congestive heart failure (CHF) and left ventricular systolic dysfunction (LVSD) has been demonstrated previously in various populations, but data on primary care patients are sparse. The aim of this study was to evaluate the diagnostic and prognostic performance of NT-proBNP in primary care patients with suspected CHF.

METHODS AND RESULTS

Three hundred sixty-seven consecutive patients (mean age, 68.8 years; range, 39.0-84.0 years) who had been referred by their general practitioner for echocardiographic evaluation because of suspected CHF. In all patients, NT-proBNP was measured at baseline and left ventricular ejection fraction (LVEF) was estimated with echocardiography. LVSD (LVEF < or =0.40) was found in 9% of the patients. NT-proBNP was significantly higher in patients with LVSD (P < .0001). With predefined cut off values for NT-proBNP (125 pg/mL), the sensitivity, specificity, positive predictive value, and negative predictive value for the detection of LVSD were 0.97, 0.46, 0.15 and 0.99, respectively. Area under the receiver operating characteristic curve was 0.87. The application of an age-differentiated cut-off value for NT-proBNP (125 pg/mL for <75 years old and 450 pg/mL for > or =75 years old) did not increase diagnostic performance. Patients were followed for a median of 778 days; 8% of the patients died during the follow-up period. The mortality rate was higher in patients with NT-proBNP of >125 pg/mL than in patients with normal values (P < .002, log rank), and the difference persisted after controlling for age, gender, and LVEF (hazard ratio per unit increase in log NT-proBNP, 2.2; range, 1.2-4.1; P = .015).

CONCLUSION

In primary care patients who were referred for echocardiography because of suspected CHF, NT-proBNP values <125 pg/mL effectively rule out LVSD. Furthermore low NT-proBNP values are associated with a lower risk of death, independently of age, gender, and LVEF.

Correlation between levels of N-terminal pro-B-type natriuretic peptide and degrees of heart failure

BACKGROUND

The N-terminal fragment of pro Brain Natriuretic Peptide (NT-pro BNP) is a neuro-hormone synthesized in the cardiac ventricles in response to increased wall tension. The purpose of this study was to assess the correlation between the NT-pro BNP levels and the New York Heart Association function class (NYHA Fc) of dyspnea and echocardiographic findings for the patients who visited our cardiology departments.

METHODS

From October, 2002 to April, 2003, serum NT-pro BNP levels were measured in 348 patients who visited the Samsung Medical Center and the Jong Koo Lee Heart Clinic.

RESULTS

The NT-pro BNP levels were increased with the progression of NYHA Fc of dyspnea (p < 0.001 by ANOVA), the increase in the systolic left ventricular internal dimension (p < 0.05), and the decrease in the ejection fraction (p < 0.01). For the NYHA Fc I patients, the NT-pro BNP levels were positively correlated with age (0 < 0.001) and left atrial size (p < 0.001). For the patients with ischemic heart disease, the NT-pro BNP levels were also positively correlated with the NYHA Fc (p < 0.001 by ANOVA). The NT-pro BNP levels were increased with the increase in the systolic (p < 0.001) and diastolic pressure (p = 0.017), the left ventricular internal dimension as well as the decrease in the ejection fraction (p < 0.001). The area under the receiver operating characteristic (ROC) curve for the NT-pro BNP levels was 0.994 (95% confidence interval, 0.979-0.999), and the most reliable cut-off level for the NT-pro BNP was 293.6 pg/mL.

CONCLUSION

The NT-pro BNP levels were positively correlated with the NYHA Fc of dyspnea and the systolic dysfunction for the patients who visited our cardiology departments. A 300 pg/mL value for the NT-pro BNP cut-off point appears to be a sensitive level to differentiate dyspnea originating from an ailing heart or not for the patients who visited our cardiology departments.

Nesiritide for the treatment of decompensated heart failure

Heart failure is the leading cause of hospitalizations in the USA, and is associated with significant morbidity, mortality and resource utilization. Established therapies for chronic heart failure have been shown to improve outcomes, but treatment for decompensated heart failure remains largely empiric. Nesiritide (Natrecor) is a synthetic analog of human B-type natriuretic peptide, a peptide released by the ventricular myocardium in response to increased wall tension. The physiologic effects of human B-type natriuretic peptide include natriuresis, vasodilation and neurohormonal modulation. In clinical trials, nesiritide has been shown to decrease cardiac filling pressures, increase cardiac index, and improve the clinical status of patients with acute decompensated heart failure. Compared with other available intravenous agents for heart failure, nesiritide is effective, generally well-tolerated with few adverse effects, and does not require invasive monitoring during administration. Nesiritide has proven to be an effective new treatment for patients with decompensated heart failure.

Brain natriuretic peptide in the contemporary management of congestive heart failure

Brain natriuretic peptide is a cardiac neurohormone that is secreted by the left ventricle in response to an increase in wall stress. Brain natriuretic peptide has emerged as a neurohormone with multiple roles in heart failure management. This review will discuss the role of brain natriuretic peptide in heart failure diagnosis, prognostic assessment, screening for asymptomatic left-ventricular dysfunction, and in the treatment of heart failure.

B-type natriuretic peptide measurement in heart failure

Serum testing for the hormone B-type natriuretic peptide (BNP) may have clinical utility in congestive heart failure (CHF). This hormone is secreted predominantly by the left ventricular myocardium in patients with CHF. Measurement of serum BNP may improve diagnosis of CHF and may also help guide therapy in patients with CHF. The literature regarding the clinical utility of BNP measurement in CHF is reviewed.

BNP Consensus Panel 2004: A Clinical Approach for the Diagnostic, Prognostic, Screening, Treatment Monitoring, and Therapeutic Roles of Natriuretic Peptides in Cardiovascular Diseases

Among the most exciting developments in the field of heart failure in recent times has been the rediscovery of the natriuretic peptide system and its pleuripotent effects on cardiac structure and function. This is particularly true of its natriuretic and hemodynamic effects. There has been an explosion of the knowledge base seeking to understand the wide range of homeostatic, regulatory, and counter-regulatory functions in which the natriuretic peptide system participates. Additional interest has been stimulated by advances in technology such as point-of-care and core laboratory BNP assays and the use of the recombinant B-type natriuretic peptide nesiritide as a treatment option. Despite this recent interest, the available literature lacks a comprehensive expert review of the current science and roles of natriuretic peptides for diagnostic, prognostic, screening, treatment monitoring, and therapeutic purposes. More importantly, a summary updating and guiding the clinician on most of these advances was lacking. An expert Consensus Panel with basic, methodological, and clinical expertise was convened to summarize current knowledge in these areas and the findings and consensus statements are contained herein.

Usefulness of B-type Natriuretic Peptide (BNP) as a screen for left ventricular abnormalities in diabetes mellitus

Cardiovascular disease is the leading cause of morbidity and mortality in diabetic subjects. Diabetes, independently of the mechanism, is associated with an increased risk of left ventricular hypertrophy, left ventricular dysfunction and coronary artery disease. B-type natriuretic peptide (BNP) is a cardiac neurohormone predominantly released from the cardiac ventricles in response to left ventricular volume expansion and pressure overload. Numerous studies have shown that BNP levels are elevated in asymptomatic or symptomatic left ventricular dysfunction, hypertrophy and coronary artery disease. BNP testing plays an important role in the screening and diagnosis of left ventricular dysfunction by improving the performance of non-specialist physicians in diagnosing heart failure. In clinical practice, BNP testing is best used as a 'rule out' test targeted to patients at high risk for left-ventricular dysfunction, such as those with diabetes. Studies are needed to establish if this promising biological tool, in the next future, would assist the management of diabetic patients.

Usefulness of an elevated B-type natriuretic peptide to predict allograft failure, cardiac allograft vasculopathy, and survival after heart transplantation

B-type natriuretic peptide (BNP) has emerged as an important marker of ventricular wall stress and is predictive of hemodynamic abnormalities in heart transplantation despite "preserved" systolic function. We evaluated the capacity of BNP to predict deaths due to allograft failure in 62 patients long after heart transplantation (mean 5 +/- 2.5 years). Based on the median tendency of measurement of BNP in the absence of rejection during stable surveillance, 2 distinct patient groups were identified as having low BNP (n = 39, < 250 pg/ml; median BNP 70 pg/ml) and high BNP (n = 23, > or =250 pg/ml; median BNP 592 pg/ml). No differences between the 2 BNP groups were noted with regard to age, gender, race, time after transplantation, diabetes mellitus, hypertension, and hyperlipidemia with measurement of BNP. Multivariable analysis showed that decreased left ventricular ejection fraction, angiographic coronary artery disease, and increased serum creatinine were independent predictors of elevated BNP. Cardiac deaths were significantly greater in those with high BNP levels (35%) than in those with low BNP (2.5%, p = 0.01). Absence of significant angiographic coronary artery disease coupled with a BNP of < 250 pg/ml was associated with the lowest event rate (0%), whereas patients with coronary artery disease and BNP > or =250 pg/ml exhibited a 50% cardiac death rate (p <0.01 for trend). Cox's model confirmed that increased BNP and decreased left ventricular ejection fraction are independent predictors of poor survival. Survival analysis associated lower BNP levels with an excellent long-term survival rate (95%) and higher BNP levels with a markedly decreased survival rate (60%, p = 0.002). Higher BNP levels in patients long after heart transplantation are associated with allograft dysfunction and cardiac allograft vasculopathy and are strongly and independently predictive of cardiovascular death.

The effect of class-specific protease inhibitors on the stabilization of B-type natriuretic peptide in human plasma

BACKGROUND

B-type natriuretic peptide (BNP) is a cardiac hormone that regulates hemodynamic equilibrium. In the circulation, its activity is controlled by proteolytic factors. Accurate measurement of BNP in a patient's plasma may be affected by degradation due to proteolysis.

OBJECTIVE

We report on the identification and performance of classes of protease inhibitors that stabilize BNP in plasma.

DESIGN AND METHODS

Using the Bayer ADVIA Centaur BNP assay, we measured the effect of arginine, serine and/or specific kallikrein protease inhibitors (PIs) on exogenous spiked or endogenous BNP in patient plasma.

RESULTS

Compared to controls without inhibitor, all PIs were capable, to varying degrees, of retarding the rate of proteolytic degradation. The kallikrein-specific inhibitor, D-Phe-Phe-Arg-chloromethylketone (PPACK II) was most effective as a single constituent and was able to eliminate BNP degradation in patient samples for up to 6-10 days when stored at 2-8 degrees C.

CONCLUSIONS

The stability of BNP was markedly increased in the presence of kallikrein-specific PPACK II and a broad spectrum of serine PIs. Use of these compounds offers a simple method of extending sample handling and storage of plasma samples containing BNP.

Natriuretic peptide measurement as a screening test for overt and subclinical heart failure

The prevalence of heart failure will increase in a number of industrialized countries as the proportion of elderly within the population increases. Despite recent advances in medical and surgical intervention, the prognosis for this disorder has not improved significantly. To make a major impact on the prognosis for heart failure, it would be important to be able to recognize various forms of heart disease before severe heart failure has developed. Chest X-radiography, ECG and echocardiography may not be adequate screening tools for heart failure in large populations. Natriuretic peptides are secreted from the heart in response to various cardiac abnormalities including ventricular dysfunction, volume overload, hypertrophy, and myocardial ischemia. Circulating levels of natriuretic peptides are elevated in various forms of structural cardiac disease regardless of etiology and the degree of ventricular systolic dysfunction. Natriuretic peptides, specifically B-type natriuretic peptide, are practically stable and can be measured without an extraction procedure. We have reviewed the recent status of plasma natriuretic peptide measurement for identification of patients with congestive heart failure, left ventricular dysfunction, and high risk of heart failure, especially in mass screening settings.

B-type natriuretic peptide: physiologic role and assay characteristics

The discovery of cardiac natriuretic peptides two decades ago has lead to considerable research to investigate their biochemical and physiological properties. Clearly the heart is not just a pump but is also an endocrine organ that together with the kidneys control volume overload. The natriuretic peptides are a group of structurally similar but genetically distinct peptides that exhibit diverse actions in cardiovascular, renal, and endocrine homeostasis. Atrial natriuretic peptide (ANP) and brain (or B-type) natriuretic peptide (BNP) are of myocardial cell origin. BNP is released mainly from the left ventricle in response to volume overload and has become the first biochemical marker for the identification of individuals with congestive heart failure (CHF). The development of assays, including rapid point-of-care tests, has made BNP measurement a clinical reality.

B-type natriuretic peptide in heart transplantation: an important marker of allograft performance

The successful management of a cardiac allograft recipient centers around detection of allograft dysfunction early and preferably in a noninvasive manner. Up to this point, echocardiography or right heart catherization with endomyocardial biopsy are the only definitive methods available to diagnose allograft dysfunction. However, these methods do not reflect early structural changes and neurohormonal aberrations involved in allograft dysfunction. B-type natriuretic peptide (BNP) reflects ventricular wall stress and pressure and early studies have intimated potential usefulness of this marker in heart transplantation. Recent studies utilizing point-of-care BNP assay in heart transplant recipients have demonstrated elevated BNP levels at baseline compared with controls. Furthermore, the two most significant correlates of BNP levels are central hemodynamic perturbations despite preserved systolic function and presence of right sided cardiac dysfunction. Initial investigations have demonstrated BNP levels to serve as prognostic marker for cardiac related events and to track responses to therapeutic interventions. Further studies are needed to further assess the utility of BNP as surrogate marker for cardiac function and adaptation.

The use of brain natriuretic peptide as a screening test for left ventricular systolic dysfunction- cost-effectiveness in relation to open access echocardiography

BACKGROUND

Heart failure due to left ventricular systolic dysfunction (LVSD) has a high prevalence in the adult population but is difficult to diagnose accurately on clinical grounds in the community. Early diagnosis is important as effective treatments are available to reduce morbidity and mortality. Echocardiography is widely used to assess heart failure; however, this technology is relatively expensive and of limited availability. A potential diagnostic aid in primary care is the measurement of plasma brain natriuretic peptide (BNP).

OBJECTIVE

This study was performed to assess the value of BNP measurement as a selective pre-screen for breathless patients referred for open access echocardiography.

METHODS

BNP was measured by radioimmunoassay with prior extraction in 83 breathless subjects (age range 37-87 years, mean 72). Standard echocardiography was performed and left ventricular systolic function was assessed.

RESULTS

The prevalence of LVSD was 31% in this group. At cut-off values chosen to give negative predictive values for LVSD of >98% (BNP = 19 pg/ml), the sensitivity, specificity and positive predictive value for BNP were 100, 49.1 and 46.9%. Using this BNP threshold as a pre-screen for echocardiography would make a net saving of pound 964.20 without compromising the diagnostic accuracy.

CONCLUSION

BNP measurement appears to have a significant cost-effective benefit for the selection of patients for echocardiography.

Cardiac hormones as diagnostic tools in heart failure

In patients with heart failure, plasma levels of atrial natriuretic peptide (ANP), B-type natriuretic peptide (BNP), and the N-terminal fragments of their prohormones (N-ANP and N-BNP) are elevated, because the cardiac hormonal system is activated by increased wall stretch due to increased volume and pressure overload. Patients suspected of having heart failure can be selected for further investigations on the basis of having an elevated plasma concentration of N-ANP, BNP, and N-BNP. High levels of cardiac hormones identify those at greatest risk for future serious cardiovascular events. Moreover, adjusting heart failure treatment to reduce plasma levels of N-BNP may improve outcome. Cardiac hormones are most useful clinically as a rule-out test. In acutely symptomatic patients, a very high negative predictive value is coupled with a relatively high positive predictive value. Measurement of cardiac hormones in patients with heart failure may reduce the need for hospitalizations and for more expensive investigations such as echocardiography. However, there have also been conflicting reports on the diagnostic value of cardiac hormones, they are not specific for any disease, and the magnitude of the effects of age and gender on BNP in the normal subgroup suggests that these parameters need to be considered when interpreting cardiac hormone levels.

Rapid bedside measurement of brain natriuretic peptide in patients with chronic heart failure

BACKGROUND

Brain natriuretic peptide (BNP) levels have been used to assess clinical status and predict prognosis of patients with chronic heart failure (CHF). However, BNP levels can only be measured in specialized laboratories which has hampered its use in daily clinical practice. We compared a new, rapid, BNP assay with a conventional BNP measurement and evaluated the applicability to current practice by comparing it with standard clinical parameters.

METHODS

BNP levels were determined in 78 stable CHF patients and 20 controls. The severity of CHF was assessed by determination of New York Heart Association functional class (NYHA), left ventricular ejection fraction (LVEF) and peak oxygen consumption (peak VO(2)), and these parameters were compared to BNP levels.

RESULTS

Overall, rapid BNP assessment was highly correlated with the conventional BNP assay (r=0.95, P<0.0001). In the higher ranges (>200 pmol/l), however, correlation was less accurate, and tended to overestimate. BNP levels also strongly correlated with both NYHA class, LVEF and peak VO(2) (all P<0.001). A cut-off value for BNP of 20 pmol/l yielded a sensitivity of 91% and a specificity of 92% to detect the presence of left ventricular systolic dysfunction.

CONCLUSIONS

Rapid measurement of BNP levels is comparable to conventional BNP measurement and strongly correlated to clinical tests that are currently used to stratify CHF patients. Wider use of this method may yield a reduction of costly and time-consuming clinical tests and may reduce the medical burden of CHF.

Role of brain natriuretic peptide in the diagnosis and management of heart failure: current concepts

BACKGROUND

Progression of heart failure is related to ventricular remodeling, a process associated to neurohormonal activation. Brain natriuretic peptide (BNP), a member of the natriuretic peptide family, has recently emerged as an important neurohormone in the pathophysiology of heart failure.

METHODS

In this update, some of the recent advances on the role of BNP in heart failure are summarized. In particular, the role of BNP in diagnosis of heart disease, as a prognostic marker of cardiovascular events and as a possible guide to optimize heart failure therapy is discussed.

RESULTS

Recent results from 4,300 patients enrolled in the Valsartan Heart Failure Trial (Val-HeFT) confirmed that BNP is the strongest predictor of outcome in heart failure, when compared to other neurohormones and clinical markers. The current use of BNP in the screening and diagnosis of heart failure and its possible future roles are presented.

CONCLUSION

In recent years, there has been an impressive accumulation of data supporting an important role of BNP as a diagnostic and prognostic marker of heart failure. Development of rapid, accurate and affordable diagnostic methods will allow the routine monitoring of BNP in a wide spectrum of settings, from general practice to controlled clinical trials.

Prevention of heart failure

BACKGROUND

The number of people in the United States with heart failure (HF) is expected to rise dramatically as the population ages unless efforts to prevent HF improve.

METHODS AND RESULTS

PubMed/MEDLINE searches were conducted to identify treatment trials of hypertension, hypercholesterolemia, asymptomatic left ventricular systolic dysfunction, and diabetes that reported HF incidence. Treatment of hypertension reduces the incidence of HF by approximately 50%, even among very elderly patients. Diuretics, beta-blockers, and angiotensin-converting enzyme (ACE) inhibitors appear more effective than calcium channel blockers and doxazosin. Hydroxy methylglutaryl coenzyme A (HMG CoA) reductase inhibitors reduce the incidence of HF by approximately 20% among patients with hypercholesterolemia and coronary artery disease. ACE inhibitors reduce HF incidence by 37% among patients with reduced systolic function and by 23% among patients with coronary artery disease and normal systolic function. Observational studies have shown lower HF incidence among people with diabetes with better glycemic control. Unfortunately, all of these effective therapies appear to be underused, and control of hypertension is particularly poor.

CONCLUSIONS

If clinical practice can live up to the potential shown from clinical trials, the suffering and economic toll imposed by HF can be dramatically reduced. Improved control of hypertension, primary prevention of myocardial infarction, and more widespread use of secondary prevention measures are essential.

Cardiac function after orthotopic liver transplantation and the effects of immunosuppression: a prospective randomized trial comparing cyclosporin (Neoral) and tacrolimus

There are several case reports in the literature that describe cardiac complications in the first few weeks after orthotopic liver transplantation (OLT) in patients receiving tacrolimus as their primary immunosuppressive therapy. In this study, we investigated the cardiac function of patients on tacrolimus (T) compared with those on cyclosporin (C) (Neoral; Novartis, Basel, Switzerland) immunosuppression, after OLT, in a prospective randomized trial. We randomized 40 adult patients with cirrhosis to either T or C with azathioprine and prednisolone immunosuppression and followed up on them for 3 months after OLT. All had detailed clinical, biochemical, electrocardiographic and echocardiographic assessments at regular intervals. Abnormalities in cardiac function were common after OLT and significant deterioration in left ventricular diastolic function was demonstrable up to 3 months in both patient groups. Cardiac function was similar in the T and C arms and no significant electrocardiographic differences were observed, although reduced heart rate variability (HRV) and higher mean serum brain natriuretic peptide (BNP) levels were identified in the T group. The percentage increase in posterior wall thickness was higher in the T group. Cardiac dysfunction as shown by worsening echocardiographic measures of left ventricular diastolic function and by clinical cardiac events is common in the first 3 months after OLT in patients with cirrhosis. HRV and BNP values in the T group were worse than in the C group, but this was not translated to an increase in cardiac clinical events in this study.

BNP and congestive heart failure

Brain natriuretic peptide (BNP), a peptide hormone secreted chiefly by ventricular myocytes, plays a key role in volume homeostasis. The plasma concentration of BNP is raised in various pathological states, especially heart failure. Many studies suggest that measurement of plasma BNP has clinical utility for excluding a diagnosis of heart failure in patients with dyspnea or fluid retention and for providing prognostic information in those with heart failure or other cardiac disease. It may also be of value in identifying patients after myocardial infarction in whom further assessment of cardiac function is likely to be worthwhile. Preliminary evidence suggests that measuring the plasma concentration of BNP may be useful in fine tuning therapy for heart failure. Artificially raising the circulating levels of BNP shows considerable promise as a treatment for heart failure. With simpler assay methods now available, it is likely that many physicians will measure plasma BNP to aid them in the diagnosis, risk stratification, and monitoring of their patients with heart failure or other cardiac dysfunction.

[Brain natriuretic peptide. Diagnostic value in heart failure]

BACKGROUND

Nowadays a number of diverse biochemical markers have been identified in patients with heart failure (HF) that could indicate the severity of the patients' illness. Among them, probably the most useful is brain natriuretic peptide (BNP) because it is easily obtained and because of its diagnostic and prognostic information. Our objective was to assess the association between BNP and other different associated variables previously known to be related to the evolution of HF, as well as its utility to distinguish systolic from diastolic HF.

PATIENTS AND METHOD

We studied 114 patients admitted consecutively for symptomatic HF for all causes (age: 66 years, male: 60%). In all patients plasma BNP was measured, from the third day of admission, with a specific radioinmunoassay. Echocardiography was performed in 101 patients.

RESULTS

BNP plasma levels increased in proportion to functional class (p = 0.01) and the degree of left ventricular dysfunction (p = 0.0001, r = 0.44). There was also an association between BNP and male sex (p = 0.008), higher plasmatic creatinine (p = 0.01, r = 0.25), Iarger ventricular diameters (p = 0.0001) and higher pulmonary systolic pressure (p = 0.001, r = 0.44). In the multivariate analysis, BNP was independently related to the rest of variables with left systolic ventricular function (p = 0.0001). Despite this association, we did not find a satisfactory cut-off value in BNP, with a good sensitivity and specificity value from the total number of patients, of which specifically systolic dysfunction as a cause of HF was detected.

CONCLUSIONS

a) BNP increases proportionately to the left ventricular dysfunction and HF severity, and b) BNP is not a useful tool to distinguish systolic from diastolic HF.

B-type natriuretic peptide in the diagnosis and management of congestive heart failure

Finding a simple blood test that would aid in the diagnosis and management of patients with CHF clearly would have a favorable impact on the staggering costs associated with the disease. BNP, which is synthesized in the cardiac ventricles and correlates with LV pressure, amount of dyspnea, and the state of neurohormonal modulation, makes this peptide the first potential "white count" for heart failure. The fact that a point-of-care rapid assay for BNP has been approved by the FDA gives the clinician an opportunity to explore its potential usefulness. The author's data, and data from others, suggest that serial point-of-care testing of BNP will be of immense help in patients presenting to urgent care clinics with dyspnea. Additionally, BNP might serve as a screen for patients referred for echocardiography. A low BNP level makes echocardiographic indices of LV dysfunction (systolic and diastolic) highly unlikely. BNP also might be an effective way to improve the in-hospital management of patients admitted with decompensated CHF. In some instances, BNP levels may obviate the need for invasive hemodynamic monitoring and, in cases where such monitoring is used, may help tailor treatment of the decompensated patient. Finally, the role of BNP in the outpatient cardiac or primary care clinic may be one of critical importance in titration of therapies and in assessment of the state of neurohormonal compensation of the patient.

ADEPT: Addition of the AT1 receptor antagonist eprosartan to ACE inhibitor therapy in chronic heart failure trial: hemodynamic and neurohormonal effects

BACKGROUND

Persistent activation of the renin-angiotensin-aldosterone-system (RAAS) is known to occur in patients with chronic heart failure (CHF) despite treatment with angiotensin-converting enzyme inhibitor (ACE) therapy. When added to ACE inhibitors, angiotensin II type 1 (AT1) antagonists may allow more complete blockade of the RAAS and preserve the beneficial effects of bradykinin accumulation not seen with AT1 receptor blockade alone.

METHODS

Thirty-six patients with stable New York Heart Association class II-IV CHF receiving ACE inhibitor therapy were randomly assigned in a double-blind manner to receive either eprosartan, a specific competitive AT1 receptor antagonist (400 to 800 mg daily, n = 18) or placebo (n = 18) for 8 weeks. The primary outcome measure was left ventricular ejection fraction (LVEF) as measured by radionuclide ventriculography, and secondary measures were central hemodynamics assessed by Swan-Ganz catheterization and neurohormonal effects.

RESULTS

There was no change in LVEF with eprosartan therapy (mean relative LVEF percentage change [SEM] +10.5% [9.3] vs +10.1% [5.0], respectively; difference, 0.4; 95% confidence interval [CI], -20.8 to 21.7; P =.97). Eprosartan was associated with a significant reduction in diastolic blood pressure and a trend toward a reduction in systolic blood pressure compared with placebo (-7.3 mm Hg [95% CI, -14.2 to -0.4] diastolic; -8.9 mm Hg [95% CI, -18.6 to 0.8] systolic). No significant change in heart rate or central hemodynamics occurred during treatment with eprosartan compared with placebo. A trend toward an increase in plasma renin activity was noted with eprosartan therapy. Eprosartan was well tolerated, with an adverse event profile similar to placebo, whereas kidney function remained unchanged.

CONCLUSIONS

When added to an ACE inhibitor, eprosartan reduced arterial pressure without increasing heart rate. There was no change in LVEF after 2 months of therapy with eprosartan.

Utility of B-natriuretic peptide as a rapid, point-of-care test for screening patients undergoing echocardiography to determine left ventricular dysfunction

BACKGROUND

Although echocardiography is an important tool for making the diagnosis of left ventricular (LV) dysfunction, the cost of this procedure limits its use as a routine screening tool for this purpose. Brain natriuretic peptide (BNP) accurately reflects ventricular pressure, and preliminary studies have found it to be highly sensitive and highly specific in diagnosing congestive heart failure in the emergency department. We hypothesized that BNP might therefore be useful as a screening tool before echocardiography in patients with suspected LV dysfunction.

METHODS

Subjects included patients referred for echocardiography to evaluate the presence or absence of LV dysfunction. Patients with known LV dysfunction were excluded from analysis. BNP was measured by a point-of-care immunoassay (Biosite Diagnostics, San Diego, Calif). The results of BNP levels were blinded from cardiologists making the assessment of LV function. Patients were divided into those with normal ventricular function, abnormal systolic ventricular function, abnormal diastolic function, and evidence of both systolic and diastolic dysfunction.

RESULTS

Two hundred patients in whom LV function was unknown were studied. In the 105 patients (53%) whose ventricular function was subsequently determined to be normal by echocardiography, BNP levels averaged 37 +/- 6 pg/mL. This was significantly less than in those patients with either ultimate diastolic dysfunction (BNP 391 +/- 89 pg/mL (P <.001) or systolic dysfunction (BNP 572 +/- 115 pg/mL (P <.001). A receiver-operator characteristic curve showing the sensitivity and specificity of BNP against the echocardiography diagnosis revealed the area under the curve (accuracy) was 0.95. At a BNP level of 75 pg/mL was 98% specific for detecting the presence or absence of LV dysfunction by echocardiography.

CONCLUSIONS

A simple, rapid test for BNP, which can be performed at the bedside or in the clinic, can reliably predict the presence or absence of LV dysfunction on echocardiogram. The data indicate that BNP may be an excellent screening tool for LV dysfunction and may, in fact, preclude the need for echocardiography in many patients.

A rapid test for B-type natriuretic peptide correlates with falling wedge pressures in patients treated for decompensated heart failure: a pilot study

OBJECTIVES

To determine if changes in B-type natriuretic peptide (BNP) levels can accurately reflect acute changes in pulmonary capillary wedge pressure during treatment of decompensated heart failure.

BACKGROUND

Tailored therapy of decompensated congestive heart failure with hemodynamic monitoring is controversial. Other than the expense and complications of Swan-Ganz catheters, its use in titration of drug therapy has no conclusive end point. Because BNP reflects both elevated left ventricular pressure and neurohormonal modulation and has a short half-life, we hypothesized that levels of BNP would decline in association with falling wedge pressures. Final BNP levels would perhaps signify a new set point of neuromodulation.

METHODS AND RESULTS

Twenty patients with decompensated New York Heart Association (NYHA) class III-IV congestive heart failure (CHF) undergoing tailored therapy were studied. BNP levels were drawn every 2 to 4 hours for the first 24 hours (active treatment phase) and then every 4 hours for the next 24 to 48 hours (stabilization period). Hemodynamic data was recorded simultaneously. In 15 patients whose wedge pressure responded to treatment in the first 24 hours, there was a significant drop in BNP levels (55%) versus nonresponders (8%). There was a significant correlation between percent change in wedge pressure from baseline per hour and the percent change of BNP from baseline per hour (r = 0.79, P <.05). When the wedge pressure was kept at a stable, low level during the stabilization phase, BNP levels continued to fall another 37% (937 +/- 140 pg/mL at 24 hours to 605 +/- 128 pg/mL). Patients who died (n = 4) had higher final BNP levels (1,078 +/- 123 pg/mL v 701 +/- 107 pg/mL).

CONCLUSIONS

The data suggest that rapid testing of BNP may be an effective way to improve the in-hospital management of patients admitted with decompensated CHF. Although BNP levels will not obviate the need for invasive hemodynamic monitoring, it may be a useful adjunct in tailoring therapy to these patients.

Utility of B-type natriuretic peptide in the diagnosis of congestive heart failure in an urgent-care setting

OBJECTIVES

The goal of this study was to evaluate the utility of a rapid "bedside" technique for measurement of B-type natriuretic peptide (BNP) in the diagnosis of congestive heart failure (CHF) in an urgent-care setting.

BACKGROUND

B-type natriuretic peptide is a protein secreted from the cardiac ventricles in response to pressure overload. One potential application of measurements of BNP in blood is distinguishing dyspnea due to CHF from other causes.

METHODS

B-type natriuretic peptide concentrations were measured in a convenience sample of 250 predominantly male (94%) patients presenting to urgent-care and emergency departments of an academic Veteran's Affairs hospital with dyspnea. Results were withheld from clinicians. Two cardiologists retrospectively reviewed clinical data (blinded to BNP measurements) and reached a consensus opinion on the cause of the patient's symptoms. This gold standard was used to evaluate the diagnostic performance of the BNP test.

RESULTS

The mean BNP concentration in the blood of patients with CHF (n = 97) was higher than it was in patients without (1,076 +/- 138 pg/ml vs. 38 +/- 4 pg/ml, p < 0.001). At a blood concentration of 80 pg/ml, BNP was an accurate predictor of the presence of CHF (95%); measurements less than this had a high negative predictive value (98%). The overall C-statistic was 0.97. In multivariate analysis, BNP measurements added significant, independent explanatory power to other clinical variables in models predicting which patients had CHF. The availability of BNP measurements could have potentially corrected 29 of the 30 diagnoses missed by urgent-care physicians.

CONCLUSIONS

B-type natriuretic peptide blood concentration measurement appears to be a sensitive and specific test to diagnose CHF in urgent-care settings.

A rapid bedside test for B-type peptide predicts treatment outcomes in patients admitted for decompensated heart failure: a pilot study

OBJECTIVES

The goal of this study was to determine if B-type natriuretic peptide (BNP) levels predict outcomes of patients admitted with decompensated heart failure.

BACKGROUND

Treatment of decompensated congestive heart failure (CHF) has often been based on titration of drugs to relieve patient's symptoms, a case that could be made for attempting to also treat neurohormonal abnormalities. Because BNP reflects both elevated left ventricular pressure as well as neurohormonal modulation, we hypothesized that BNP might be useful in assessing outcomes in patients admitted with decompensated CHF.

METHODS

We followed 72 patients admitted with decompensated New York Heart Association class III to IV CHF, measuring daily BNP levels. We then determined the association between initial BNP measurement and the predischarge or premoribund BNP measurement and subsequent adverse outcomes (death and 30-day readmission).

RESULTS

Of the 72 patients admitted with decompensated CHF, 22 end points occurred (death: n = 13, readmission: n = 9). In these patients, BNP levels increased during hospitalization (mean increase, 233 pg/ml, p < 0.001). In patients without end points, BNP decreased (mean decrease 215 pg/ml). Univariate analysis revealed that the last measured BNP was strongly associated with the combined end point. In patients surviving hospitalization, BNP discharge concentrations were strong predictors of subsequent readmission (area under the receiver operator curve of 0.73).

CONCLUSIONS

In patients admitted with decompensated CHF, changes in BNP levels during treatment are strong predictors for mortality and early readmission. The results suggest that BNP levels might be used successfully to guide treatment of patients admitted for decompensated CHF.

Practical implications of current natriuretic peptide research

Since the original discovery of atrial natriuretic peptide (ANP) nearly 20 years ago and the subsequent realisation of the existence of a family of natriuretic peptides, there has been considerable progress in the elucidation of the physiological and pathophysiological significance of these peptides. This review has examined two potentially important practical aspects arising from natriuretic peptide research - the significance of measurement of plasma levels of ANP and of brain natriuretic peptide BNP for cardiovascular disease and the therapeutic potential of targeting the natriuretic peptide system. Several situations where the measurement of plasma ANP and BNP may be of benefit in the overall assessment and prognosis of cardiac disease have been discussed. The measurement of plasma levels of these peptides appears to have limited value as a specific diagnostic tool and is unlikely to replace well-established procedures to assess cardiac function. Nevertheless, given the strong negative predictive value, the value of the measurement of plasma natriuretic peptides particularly BNPs, in people with suspected heart disease, rests on the evidence that a normal value indicates a low risk of cardiac impairment. Moreover, a consistently elevated plasma level of BNP after myocardial infarction is associated with a distinctly poor prognosis. In turn, this may help to select those with high plasma levels for subsequent detailed investigation of cardiac dysfunction. This may be an important option, especially where the facilities for the more invasive cardiological procedures are not available. Intriguingly, recent research also suggests the possibility that plasma levels of natriuretic peptides may have an important role in guiding more effective therapy for heart failure. The potent cardiovascular and renal effects of ANP and BNP provide an important therapeutic potential for hypertension and for conditions associated with volume overload. A number of approaches which have been used to enhance endogenous activity of these peptides have been highlighted. The use of the native peptides ANP and BNP may well be valuable in some circumstances, such as in critically ill individuals with congestive heart failure or renal failure. However, the limitations of the use of peptides, especially for long-term treatment, are obvious. In view of this, considerable effort has been devoted to the development of orally active agents to enhance endogenous natriuretic peptides by inhibition of breakdown by neutral endopeptidase. This research has led to the development of vasopeptidase inhibitors - dual inhibitors of both endopeptidase and angiotensin-converting enzyme - to enhance endogenous natriuretic peptide function on a background of reduced angiotensin II activity. The broad spectrum of action and the potentially important target-organ protection of these inhibitors offer potential benefits which may well go beyond existing treatment of hypertension and of conditions associated with overt volume overload.

Plasma concentration of brain natriuretic peptide as a biochemical marker for the evaluation of right ventricular overload and mortality in chronic respiratory disease

The purpose of this study was to evaluate whether the plasma brain natriuretic peptide (BNP) concentration is a useful marker of right ventricular (RV) overload and whether it has prognostic value as a predictor of death in patients with chronic respiratory disease (CRD). We measured the plasma BNP and atrial natriuretic peptide (ANP) concentrations in 31 consecutive patients with CRD who underwent right-heart catheterization to evaluate pulmonary hypertension. All patients were followed for >12 months. The plasma BNP concentration closely correlated with the mean pulmonary artery pressure and pulmonary vascular resistance (r=0.62, P<0.0005 and r=0. 85, P<0.0001), and showed a weak linear correlation with cardiac output (r=-0.36, P<0.05). During the follow-up period, 5 (16%) end-stage CRD deaths (4 RV heart failure and 1 respiratory infection) and 2 non-end-stage CRD deaths occurred. In a stepwise multivariate Cox proportional-hazards regression analysis including age, sex, BNP, ANP, hemodynamic variables and the ratio of PaO(2) to fraction of inspired oxygen, only BNP (P<0.05) was an independent predictor of end-stage CRD death. The upward and leftward shift in the receiver operating characteristic curve between patients with end-stage CRD death and those without was greater for BNP than for ANP. Our findings suggest that the plasma BNP concentration may be an inexpensive, simple and useful marker of RV overload and end-stage CRD death in CRD patients. These preliminary results need to be confirmed in a large series of CRD patients.