Increased brain natriuretic peptide and atrial natriuretic peptide plasma concentrations in dialysis-dependent chronic renal failure and in patients with elevated left ventricular filling pressure

Vascular refilling coefficient is not a good marker of whole-body capillary hydraulic conductivity in hemodialysis patients: insights from a simulation study

Refilling of the vascular space through absorption of interstitial fluid by micro vessels is a crucial mechanism for maintaining hemodynamic stability during hemodialysis (HD) and allowing excess fluid to be removed from body tissues. The rate of vascular refilling depends on the imbalance between the Starling forces acting across the capillary walls as well as on their hydraulic conductivity and total surface area. Various approaches have been proposed to assess the vascular refilling process during HD, including the so-called refilling coefficient (Kr) that describes the rate of vascular refilling per changes in plasma oncotic pressure, assuming that other Starling forces and the flow of lymph remain constant during HD. Several studies have shown that Kr decreases exponentially during HD, which was attributed to a dialysis-induced decrease in the whole-body capillary hydraulic conductivity (L_pS). Here, we employ a lumped-parameter mathematical model of the cardiovascular system and water and solute transport between the main body fluid compartments to assess the impact of all Starling forces and the flow of lymph on vascular refilling during HD in order to explain the reasons behind the observed intradialytic decrease in Kr. We simulated several HD sessions in a virtual patient with different blood priming procedures, ultrafiltration rates, session durations, and constant or variable levels of L_pS. We show that the intradialytic decrease in Kr is not associated with a possible reduction of L_pS but results from the inherent assumption that plasma oncotic pressure is the only variable Starling force during HD, whereas in fact other Starling forces, in particular the oncotic pressure of the interstitial fluid, have an important impact on the transcapillary fluid exchange during HD. We conclude that Kr is not a good marker of L_pS and should not be used to guide fluid removal during HD or to assess the fluid status of dialysis patients.

Does admission NT-proBNP increase the prognostic accuracy of GRACE risk score in the prediction of short-term mortality after acute coronary syndromes?

BACKGROUND

NT-proBNP has prognostic implications in heart failure. In acute coronary syndromes (ACS) setting, the prognostic significance of NT-proBNP is being sought. We studied short-term prognostic impact of admission NT-proBNP in patients admitted for ACS and in association with GRACE risk score (GRS).

METHODS AND RESULTS

We studied 1035 patients admitted with ACS. Patients were divided in quartiles according to NT-proBNP levels on admission: Q1 <180 pg/ml; Q2 180-691 pg/ml; Q3 696-2664 pg/ml; Q4 2698-35 000 pg/ml. Groups were compared in terms of short-term all-cause mortality. Patients with higher NT-proBNP had worst GRS on admission. They also received less aggressive treatment. In-hospital mortality was 0.8%, 3.0%, 5.8% and 12.8% (P<0.001) and 30-day mortality 1.6%, 4.6%, 6.5% and 16.7% (P<0.001) respectively. In multivariate logistic regression analysis, NT-proBNP is an independent predictor of in-hospital (OR 2.35; 95% CI: 1.12-4.93, P=0.022) and 30-day mortality (OR 2.20; 95% CI: 1.17-4.12, P=0.014). However, NT-proBNP does not add any incremental benefit to GRS for prediction of outcome by ROC curve analysis.

CONCLUSIONS

NT-proBNP is an independent predictor of in-hospital and 30-day mortality after ACS, independently of left ventricular function, but does not increase the prognostic accuracy of GRS.

Amino Terminal B-Type Natriuretic Peptide, Renal Function, and Prognosis in Acute Heart Failure: A Hospital Cohort Study

BACKGROUND

Amino-terminal pro-brain natriuretic peptide (NT-proBNP) is a valuable diagnostic and prognostic test in heart failure (HF). Limited information is available concerning its use in patients with renal failure, in whom dependence on renal clearance may negatively affect its performance.

METHODS AND RESULTS

We evaluated influence of renal function on NT-proBNP levels and on its prognostic value after hospital discharge in 283 acute HF patients. Admission and discharge NT-proBNP levels were higher in patients with decreased estimated glomerular filtration rate (eGFR). In these patients discharge NT-proBNP above median was associated to occurrence of death or readmission at 6 months (hazard ratio [HR] 2.53, 95% confidence interval [CI] 1.27-5.03); in patients with normal eGFR, a trend to this association was found (HR 1.64, CI 0.98-2.76). Decrease in NT-proBNP less than 30% of baseline was associated to outcome in patients with normal eGFR (HR 2.68, CI 1.54-4.68) and decreased eGFR (HR 2.54, CI 1.49-4.33).

CONCLUSIONS

Acute HF patients with renal failure have higher NT-proBNP levels than those with normal renal function. Discharge NT-proBNP has long-term prognostic value in HF patients with renal dysfunction. NT-proBNP variations during hospitalization provide additional prognostic information either in patients with normal or reduced eGFR.

Short-Term Serial Sampling of Natriuretic Peptides in Patients Presenting With Chest Pain

OBJECTIVES

The purpose of this study was to characterize the diagnostic and prognostic utility of short-term dynamic changes in natriuretic peptides in patients presenting with chest pain.

BACKGROUND

Although single levels of natriuretic peptides in patients admitted for acute coronary syndromes (ACS) have important prognostic value, it is unclear whether serial sampling of natriuretic peptides might have both diagnostic and prognostic value in the setting of chest pain.

METHODS

We followed 276 patients for 90 days who presented to the emergency department with chest pain. We sampled brain natriuretic peptide (BNP) and amino-terminal (NT)-proBNP up to 5 times within 24 h of presentation and again at discharge. Follow-up data was collected at 30 and 90 days after admission. Adverse events included emergency department visits for chest pain, cardiac readmission, and death. We assessed the prognostic and diagnostic value of baseline natriuretic peptide measurements with receiver-operating characteristic analyses.

RESULTS

Natriuretic peptides were diagnostic for congestive heart failure (CHF) and new-onset CHF but less so for ACS. The prognostic utility of serial sampling was evaluated through testing the statistical contribution of each future time point (as well as variability over time) over and above the baseline values in logistic regression models.

CONCLUSIONS

Baseline elevated BNP and NT-proBNP concentrations were predictive of adverse events at 30 and 90 days. Serial sampling did not improve the prognostic value of BNP or NT-proBNP.

Value of B-type natriuretic peptide in diagnosing left ventricular dysfunction in dialysis-dependent patients

BACKGROUND

B-type natriuretic peptide (BNP) is elevated in patients with end-stage renal failure. The reported accuracy of BNP in diagnosing left ventricular dysfunction in these patients has been inconsistent.

AIM

To investigate the diagnostic values of BNP for left ventricular dysfunction in patients undergoing haemodialysis for chronic renal failure.

METHODS

We measured plasma BNP before and at 10 min and 3, 6 and 24 h after haemodialysis in 56 patients.

RESULTS

The average plasma BNP before haemodialysis was 284 +/- 369 pg/mL, which was higher than that of healthy subjects (37 +/- 37 pg/mL; n = 32, P < 0.01). The average plasma BNP in patients with left ventricular dysfunction (n = 21) was substantially higher than that in those with normal ventricular function before and at 10 min and 3, 6 and 24 h after haemodialysis (P < 0.001). The area under the receiver operating characteristic curves was greater than 0.895 before and at the four time points after haemodialysis (P < 0.01). Using 152 pg/mL as a cut-off value, predialysis BNP has 81% sensitivity and 83% specificity in diagnosing left ventricular dysfunction in these patients.

CONCLUSION

We concluded that plasma BNP offers a good sensitivity and specificity in diagnosing left ventricular dysfunction in patients with dialysis-dependent renal failure.

Sepsis-associated myocardial dysfunction: diagnostic and prognostic impact of cardiac troponins and natriuretic peptides

Myocardial dysfunction, which is characterized by transient biventricular impairment of intrinsic myocardial contractility, is a common complication in patients with sepsis. Left ventricular systolic dysfunction is reflected by a reduced left ventricular stroke work index or, less accurately, by an impaired left ventricular ejection fraction (LVEF). Early recognition of myocardial dysfunction is crucial for the administration of the most appropriate therapy. Cardiac troponins and natriuretic peptides are biomarkers that were previously introduced for diagnosis and risk stratification in patients with acute coronary syndrome and congestive heart failure, respectively. However, their prognostic and diagnostic impact in critically ill patients warrants definition. The elevation of cardiac troponin levels in patients with sepsis, severe sepsis, or septic shock has been shown to indicate left ventricular dysfunction and a poor prognosis. Troponin release in this population occurs in the absence of flow-limiting coronary artery disease, suggesting the presence of mechanisms other than thrombotic coronary artery occlusion, probably a transient loss in membrane integrity with subsequent troponin leakage or microvascular thrombotic injury. In contrast to the rather uniform results of studies dealing with cardiac troponins, the impact of raised B-type natriuretic peptide (BNP) levels in patients with sepsis is less clear. The relationship between BNP and both LVEF and left-sided filling pressures is weak, and data on the prognostic impact of high BNP levels in patients with sepsis are conflicting. Mechanisms other than left ventricular wall stress may contribute to BNP release, including right ventricular overload, catecholamine therapy, renal failure, diseases of the CNS, and cytokine up-regulation. Whereas cardiac troponins may be integrated into the monitoring of myocardial dysfunction in patients with severe sepsis or septic shock to identify those patients requiring early and aggressive supportive therapy, the routine use of BNP and other natriuretic peptides in this setting is discouraged at the moment.

Brain Natriuretic Peptide and N-Terminal proBNP in Chronic Haemodialysis Patients

BACKGROUND

Brain natriuretic peptide (BNP) and N-terminal proBNP (NT-proBNP) are released into circulation as a result of congestive heart failure (HF). As HF and water overload are frequent complications in haemodialysis (HD) patients, we decided to study the levels of BNP and NT-proBNP and their changes during HD.

METHODS

BNP and NT-proBNP levels were determined in 94 HD patients before and after a regular 4-h HD. We followed changes in these peptides during HD depending on age, sex, HF (NYHA classification and left ventricular ejection fraction [LVEF]), duration on HD, presence of hypertension, coronary artery disease, type of membrane used for HD [low-flux (LFx) or high-flux (HFx)] and body mass change during HD. Furthermore, patients basic medication and creatinine levels and presence of diabetes mellitus were monitored.

RESULTS

Respectively,94% and 100% of the patients had pre-dialysis concentrations of BNP and NT-proBNP above the cut-off values for HF. The marker levels correlated significantly both before and after HD (r = 0.903 and 0.888, respectively, p < 0.001). BNP levels significantly decreased (p < 0.0001), whereas NT-proBNP significantly increased (p < 0.0001) during HD on LFx membranes. HD on HFx membranes caused greater decrease of BNP (compared to LFx membranes, p < 0.001), but also a decrease of NT-proBNP (p < 0.001).We did not find any significant differences in marker levels for HF and non-HF patients (NYHA classification). However, both peptides reached higher levels in the group with LVEF < or = 50% (p < 0.001 for both peptides). Body mass change during HD negatively correlated only with the change of NT-proBNP (r = -0.27, p < 0.05). In the multiple regression model, the change of both peptides during HD was significantly influenced by membrane type (p = 0.003 for BNP and p = 0.001 for NT-proBNP). NT-proBNP change during HD was further significantly influenced by LVEF (p = 0.012), sex (p = 0.002) and duration on HD (p = 0.006).

CONCLUSIONS

Both BNP and NT-proBNP levels were significantly increased in HD patients prior to dialysis. The change in concentrations of both peptides during HD is influenced by membrane type. HD probably triggers increased production of both peptides and this increase is emphasized by impaired LVEF. This fact can be clinically observed only on NT-proBNP levels, because BNP levels are biased by significant removal of this protein during HD.

Prognostic value of plasma N-terminal pro-brain natriuretic peptide in children with congenital heart defects and open-heart surgery

OBJECTIVE

To assess whether preoperative and postoperative plasma levels of N-terminal pro-brain natriuretic peptide (NT-proBNP) predict postoperative outcome of open-heart surgery in children.

STUDY DESIGN

A prospective observational study was conducted with 40 children with congenital heart defects who were undergoing elective open-heart surgery. Plasma levels of NT-proBNP, troponin T, lactate, C-reactive protein, and total neutrophil cell counts were measured before, during, and 1 and 3 hours after the end of cardiopulmonary bypass grafting (CPB). Outcomes were assessed by means of the kind, dosage, and duration of inotropic drug use during the postoperative period, lactate concentrations, and the duration of mechanical ventilation.

RESULTS

Preoperative levels of NT-proBNP were significantly increased irrespective of the type of congenital heart defect and the age of the patient. Preoperative NT-proBNP levels were higher in patients receiving prolonged postoperative inotropic drug therapy (r = 0.56, P = .0003). By means of multivariate analysis with the duration of inotropic therapy as the dependent variable, a significant impact of preoperative NT-proBNP levels, the presence of a cyanotic heart defect, the risk adjustment for congenital heart surgery score, duration of CPB time, and postoperative lactate levels were demonstrated (R squared = 76.8%, P <.0001).

CONCLUSION

Preoperative NT-proBNP levels were associated with complicated postoperative outcome in children who underwent low-risk open-heart surgery. This marker may therefore be a useful tool in risk stratification of patients with congenital heart defects.

Natriuretic Peptides and the Dialysis Patient

The natriuretic peptide family consists of four structurally similar, but genetically distinct molecules with pronounced cardiovascular and renal actions. They are counterregulatory hormones playing an important role in fluid volume homeostasis. Atrial natriuretic peptide (ANP) and B-type natriuretic peptide (BNP) cause diuresis, natriuresis, and vasodilatation. C-type natriuretic peptide (CNP) has antimitogenic effects and causes vascular smooth muscle relaxation. Dendroaspis natriuretic peptide (DNP) shares many of the actions of ANP and BNP, but its function in humans is not yet fully understood. Natriuretic peptides have been extensively investigated as biochemical markers of the fluid state. Levels are elevated in disease conditions characterized by fluid overload and are closely related to survival in various cardiac disease states. In the dialysis population, BNP correlates significantly with cardiac function, whereas ANP is sensitive to volume changes during dialysis. However, changes in concentration do not predict achievement of euvolemia, and short half-life, combined with complicated assay techniques, make ANP a less than satisfactory tool for assessing hydration. BNP is a superior prognosticator for risk stratification in dialysis patients, and serial estimations will help in the identification of occult cardiac disease.

Plasma BNP in patients on maintenance haemodialysis: a guide to management?

The number of patients requiring long-term haemodialysis is increasing throughout the world. Cardiovascular disease is much more common in these patients than in the general population and accounts for the majority of deaths. New approaches to management are clearly needed to reduce this excessive cardiovascular burden. We propose that circulating levels of the cardiac natriuretic peptides, B-type natriuretic peptide (BNP) in particular, might provide a useful, objective guide to the management of their hydration status and pharmacotherapy. An overview of the literature shows that plasma levels of the cardiac natriuretic peptides are increased in this patient population and reflect cardiac preload and afterload along with cardiac pathology, thereby providing an index of cardiovascular (especially cardiac) stress and distress. Circulating levels of the cardiac peptides change in parallel with cardiac load, especially across haemodialysis. Furthermore, there is robust evidence that natriuretic peptide levels are predictive of cardiovascular outcome in these patients. Accordingly, we hypothesize that management of their haemodialysis, and pharmacotherapy designed specifically to lower plasma BNP levels to, or close to, the normal range, will reduce the excessive burden on the cardiovascular system and thereby ultimately lower the incidence of cardiovascular disease. We outline, in broad terms, how a trial to test this hypothesis might be designed.

Changes in B-type natriuretic peptide levels in hemodialysis and the effect of depressed left ventricular function

B-type natriuretic peptide (BNP) is a cardiac neurohormone specifically secreted by the cardiac ventricles in response to volume expansion, pressure overload, and resultant increased wall tension. Previous research has shown elevated BNP levels in patients with volume overload caused by end-stage renal disease (ESRD). This pilot study was designed to describe the relative reduction in BNP that occurs as a result of hemodialysis (HD) in relation to baseline left ventricular function. Hemodialysis patients (n = 34) with ESRD were enrolled in a prospective manner. All patients had blinded serum BNP levels measured at the initiation and termination of HD. Levels of BNP were also measured in the dialysate and any residual urine, if available. In addition, monthly urea reduction ratio (URR) and Kt/V were obtained. The most recent measurement of left ventricular ejection fraction (LVEF) by any method was obtained from chart review. The BNP reduction ratio (BNPRR) was calculated by the following expression: pre-BNP-post-BNP/pre-BNP. The mean age was 50.8 years, 50.0% were male, and 55.9% were African American. A mean of 3239.4 mL of fluid was removed during HD. The mean pre-BNP, post-BNP, and change in BNP were 556.3 +/- 451.5 pg/mL, 538.6 +/- 488.3 pg/mL, and -17.6 +/-147.0 pg/mL. Of the 27 patients who had both pre-BNP and post-BNP values in the measurable range (< 1,300 pg/mL), BNP rose in 9 (33.3%) and fell in 18 (66.7%). The BNPRR had the following correlations: volume removed, r = -0.33, P = .07; Kt/V, r = -0.51, P = .01; URR, r = -0.34, P = .09; and change in body weight, r = -0.33, P = .07. The BNPRR was not correlated with time on dialysis or change in blood pressure. A total of 20 patients had LVEF recorded and post-BNP levels in the measurable range. For this group, the BNPRR values stratified by lowest to highest LVEF group were 4.6%, 19.1%, and 21.8%; P = .95 for trend. The BNP values were elevated in ESRD patients and decreased slightly during HD. This change was more pronounced in patients with normal or mildly impaired LVEF. The BNPRR correlated with the volume removed, change in body weight, and Kt/V. Future research with the BNPRR as a potential marker of the adequacy of volume removal in HD is warranted.

Utility of B-type natriuretic peptide in differentiating congestive heart failure from lung disease in pediatric patients with respiratory distress

Plasma B-type natriuretic peptide (BNP) has been reported to be helpful in differentiating cardiac from pulmonary etiologies of dyspnea in adults. We investigated whether BNP concentration could be applied similarly in children with respiratory distress. BNP levels were measured using a rapid immunoassay in 49 infants and children presenting with acute respiratory distress. The patient's history, symptoms, physical exam, chest x-ray, and an echocardiogram were used to identify patients with congestive heart failure (CHF) from noncardiac causes of respiratory distress. Results are reported as mean+/-SD. Patients with CHF (n = 23) had BNP levels of 693.0+/-501.6 pg/ml, significantly higher than those of the group of patients with lung disease (n = 26), whose BNP was 45.2+/-64.0 pg/ml (p < 0.001). There was no significant difference in age between the two groups (29.7+/-59.3 vs 13.1+/-22.6 months; p = 0.12). A BNP level of 40 pg/ml was 84% accurate in differentiating CHF from pulmonary disease. Fifteen of 23 CHF patients had ventricular volume overload from left-to-right shunting congenital heart defects and 8/23 had left ventricular systolic dysfunction. Age-adjusted comparison of the two subgroups of CHF patients revealed that children with left ventricular systolic dysfunction had significantly higher mean BNP levels than those with left-to-right shunts (1181+/-487 vs 433+/-471 pg/ml, p = 0.0074). We conclude that BNP level is of value in differentiating cardiac from pulmonary causes of respiratory distress in children.

B-type natriuretic peptide: the level and the drug--partners in the diagnosis of congestive heart failure

Over the past 100 years, cardiovascular disease has become a leading cause of morbidity and mortality worldwide. A tremendous increase in incidence and prevalence of heart failure has been observed in the United States. The cost of managing heart failure itself is $56 billion a year, 70% of which is due to hospitalization. Although we have made tremendous advances in our understanding of the pathophysiology and treatment of congestive heart failure, the diagnosis of the disease still remains difficult. Unfortunately, the signs and symptoms of congestive heart failure are nonspecific. The recognition of the role of B-type natriuretic peptide as an objective marker for the diagnosis, severity, and prognosis of acute coronary syndromes and congestive heart failure was truly a breakthrough for clinicians and patients faced with cardiovascular disease. Also, the high levels of endogenous B-type natriuretic peptide may be released as a "distress hormone"; that is, these levels are no longer effective in maintaining the balance of vasoconstriction and vasodilation. Hence it makes intuitive and practical sense that giving back B-type natriuretic peptide in the form of exogenous nesiritide might restore neurohormonal homeostasis. Therefore, lately there has been a lot of interest shown in the use of recombinant B-type natriuretic peptide as a drug. This article reviews the literature concerning the use of these peptides in a variety of clinical scenarios and the use of recombinant B-type natriuretic peptide in decompensated heart failure.

Increased plasma levels of pro-brain natriuretic peptide in patients with cardiovascular complications following off-pump coronary artery surgery

OBJECTIVE

To compare N-terminal pro-brain natriuretic peptide (NT-pro-BNP), procalcitonin (PCT), and troponin I (Tn I) concentrations during and after coronary artery surgery in patients with or without cardiovascular complications.

DESIGN AND SETTING

Prospective, comparative study of 12 months in the cardiovascular intensive care unit in a university hospital.

PATIENTS

60 adult patients undergoing coronary artery bypass grafting with the off-pump technique.

MEASUREMENTS AND RESULTS

Plasma NT-pro-BNP, PCT, and Tn I levels were measured before and immediately after the end of operation and on PODs 1, and 2 and 3. We defined complicated postoperative course as myocardial infarction, cardiogenic shock, arrhythmias, congestive heart failure, and death occurring after the fourth postoperative hour. Receiver operating characteristic (ROC) curve cutoff values were used to assess the ability of the three markers to predict future cardiac events. The area under ROC curve (AUC) using NT-pro-BNP to detect a cardiovascular complicated course was 0.780 at the preoperative time and 0.850 at the end of surgery. A preoperative NT-pro-BNP value of 397 pg/ml had a sensitivity of 76%, specificity of 67%, and accuracy of 74% for predicting a subsequent cardiovascular complication. An immediate postoperative NT-pro-BNP value of 430 pg/ml had a sensitivity of 80%, specificity of 77%, and accuracy of 76%. Patients with preoperative NT-pro-BNP levels less than 275 pg/ml had an excellent postoperative prognosis. Other two markers were less appropriate.

CONCLUSIONS

NT-pro-BNP levels measured before and immediately after off-pump coronary artery bypass seem to be predictive of postoperative cardiac events.

The diagnosis of acute congestive heart failure: role of BNP measurements

For the acutely ill patient presenting to the emergency department with dyspnea, an incorrect diagnosis could place the patient at risk for both morbidity and mortality. The stimulus for BNP release is a change in left-ventricular wall stretch and volume overload. A rapid whole blood BNP assay has recently approved by the FDA (Triage BNP Test, Biosite Inc, San Diego CA) that allows one to quickly evaluate the dyspneic patient, and set the stage for the recently completed multinational Breathing Not Properly (BNP) study. The Breathing Not Properly Multinational Study was a seven center, prospective study of 1586 patients who presented to the emergency department with acute dyspnea and had BNP measured with a point-of-care assay upon arrival. BNP was accurate in making the diagnosis of CHF and correlated to severity of disease. It could have reduced clinical indecision by 74%. Algorithms are being developed for use in the emergency room which takes into account other illnesses that might raise BNP levels. BNP levels should be extremely important in ruling out and diagnosing decompensated CHF, as long as baseline "euvolemic" BNP values are known. Finally, it is possible that use of BNP levels might not only be helpful in assessing whether or not a dyspneic patient has heart failure, but it my turn out to be useful in making both triage and management decisions.

The role and assessment of ventricular peptides in heart failure

Although heart failure may be diagnosed readily in its advanced stages, it may be difficult to diagnose clinically in its early stages.Thus, there is a critical need for an inexpensive, simple, rapid,and objective test for heart failure. This article discusses the role and assessment of ventricular natriuretic peptides and related pep-tides in heart failure.

QRS prolongation on surface ECG and brain natriuretic peptide as indicators of left ventricular systolic dysfunction

OBJECTIVE

To determine whether the combination of prolonged QRS duration and brain natriuretic peptide (BNP) levels predicts left ventricular systolic dysfunction (LVSD) with a higher accuracy compared with QRS duration or BNP alone.

SETTING

University hospital.

METHODS

We studied 128 consecutive patients with suspected cardiac disease. At rest the QRS duration on 12-lead ECG and BNP levels were determined. A left ventricular ejection fraction (LVEF) <50% at echocardiography was defined as LVSD.

RESULTS

QRS duration in the LVSD group (n = 66, LVEF 30 +/- 8%) was longer than in the group without LVSD (n = 62, LVEF 60 +/- 5%; QRS 129 +/- 34 vs. 96 +/- 20 ms, P < 0.001). BNP was higher in the LVSD group compared with controls (467 +/- 397 vs. 169 +/- 242 pg mL(-1), P < 0.001). A QRS duration of >0.1, >0.11 or >0.12 s was highly specific (63, 90 and 98%) but less sensitive (84, 81 and 75%) for the prediction of LVSD. A QRS cut-off value of 106 ms was moderately sensitive (65%) but very specific (87%) for the prediction of LVSD, whereas a BNP cut-off value of >84 pg mL(-1) was highly sensitive (89%) but only modestly specific (58%). The positive likelihood ratio for LVSD of abnormal BNP (2.0) and QRS prolongation >0.1 s (2.3) was improved by the combination of both criteria (5.1). In multivariate analysis, BNP and QRS duration were independent predictors of LVSD.

CONCLUSIONS

The combination of abnormal BNP and QRS prolongation yields a higher positive likelihood ratio for the detection of LVSD compared with the two criteria alone.

B-Type Natriuretic Peptide: A Diagnostic, Prognostic, and Therapeutic Tool in Heart Failure

B-type natriuretic peptide is a neurohormone secreted from the cardiac ventricles in response to ventricular stretch and pressure overload. It counteracts the vasoconstriction that occurs as a compensatory mechanism in heart failure. A new test for measuring plasma levels of B-type natriuretic peptide can help in the diagnosis and treatment of patients with congestive heart failure. Dyspnea associated with cardiac dysfunction is highly unlikely in patients with levels of the peptide less than 100 pg/mL. Whereas most patients with significant congestive heart failure have levels of the peptide greater than 400 pg/mL, in patients with levels of 100 to 400 pg/mL, left ventricular dysfunction without volume overload, pulmonary embolism, and cor pulmonale must be ruled out. Thus, incorporating measurement of B-type natriuretic peptide into clinical evaluation helps physicians and nurses diagnose heart failure more quickly, especially in patients who have multiple comorbid conditions. Elevated levels of B-type natriuretic peptide indicate a poor prognosis in terms of a higher mortality and more hospital readmissions. Levels of B-type natriuretic peptide could be used to guide therapy and discharge planning for patients admitted with decompensated heart failure.

The influence of age, sex and other variables on the plasma level of N-terminal pro brain natriuretic peptide in a large sample of the general population

OBJECTIVE

To identify potentially confounding variables for the interpretation of plasma N-terminal pro brain natriuretic peptide (NT-proBNP).

DESIGN

Randomly selected subjects filled in a heart failure questionnaire and underwent pulse and blood pressure measurements, ECG, echocardiography, and blood sampling.

SETTING

Subjects were recruited from four Copenhagen general practices located in the same urban area and were examined in a Copenhagen University Hospital.

PATIENTS

382 women and 290 men in four age groups: 50-59 years (n = 174); 60-69 years (n = 204); 70-79 years (n = 174); and > 80 years (n = 120).

MAIN OUTCOME MEASURES

Associations between the plasma concentration of NT-proBNP and a range of clinical variables.

RESULTS

In the undivided study sample, female sex (p < 0.0001), greater age (p < 0.0001), increasing dyspnoea (p = 0.0001), diabetes mellitus (p = 0.01), valvar heart disease (p = 0.002), low heart rate (p < 0.0001), left ventricular ejection fraction < or = 45% (p < 0.0001), abnormal ECG (p < 0.0001), high log10[plasma creatinine] (p = 0.0009), low log10[plasma glycosylated haemoglobin A1c] (p = 0.0004), and high log10[urine albumin] (p < 0.0001) were independently associated with a high plasma log10[plasma NT-proBNP] by multiple linear regression analysis.

CONCLUSIONS

A single reference interval for the normal value of NT-proBNP is unlikely to suffice. There are several confounders for the interpretation of a given NT-proBNP concentration and at the very least adjustment should be made for the independent effects of age and sex.

A rapid B-type natriuretic peptide assay accurately diagnoses left ventricular dysfunction and heart failure: a multicenter evaluation

BACKGROUND

B-Type natriuretic peptide (BNP), a protein released from the left ventricle in response to volume expansion and pressure overload, has emerged as the first whole blood marker for the identification of individuals with congestive heart failure (CHF).

OBJECTIVE

The purpose of this study was to assess the performance of a point-of-care assay to diagnose and evaluate the severity of CHF on the basis of the New York Heart Association (NYHA) classification system.

METHODS

Through a prospective, multicenter trial, whole blood samples were collected from a total of 1050 inpatients, outpatients, and healthy control patients. Participants were divided into subgroups for BNP analysis: patients without cardiovascular CHF (n = 473), patients with hypertension and no cardiovascular disease (n = 168), NYHA class I CHF (n = 73), class II CHF (n = 135), class III CHF (n = 141), and class IV CHF (n = 60).

RESULTS

Circulating BNP concentrations determined from the bedside assay increased with CHF severity, as determined by the NYHA classification system, but were only statistically significant (P <.001) between individuals with and without CHF. Individuals without CHF had a median BNP concentration of 9.29 pg/mL. Median BNP values, with their corresponding interquartile ranges, for NYHA classification I through IV were 83.1 pg/mL (49.4-137 pg/mL), 235 pg/mL (137-391 pg/mL), 459 pg/mL (200-871 pg/mL), and 1119 pg/mL (728->1300 pg/mL), respectively. With the use of a decision threshold of 100 pg/mL, the assay demonstrated 82% sensitivity and 99% specificity for distinguishing control patients and patients with CHF.

CONCLUSIONS

BNP concentrations obtained from whole blood samples are useful in the diagnosis of CHF and staging the severity of the disease.

brain natriuretic peptide levels predict functional capacity in patients with chronic heart failure

OBJECTIVES

The goal of this study was to determine if brain natriuretic peptide (BNP) levels are associated with exercise capacity in patients with chronic heart failure (HF).

BACKGROUND

Plasma levels of BNP are increased subject to the degree of systolic and diastolic left ventricular dysfunction in patients with chronic HF. Exercise testing is useful to assess functional capacity and prognosis in chronic HF.

METHODS

We prospectively studied 70 consecutive patients with chronic HF (60.3 +/- 10.4 years, 51 men) referred for cardiopulmonary exercise testing. Resting BNP was obtained after 10 min of supine rest before symptom-limited bicycle exercise testing.

RESULTS

In patients with chronic HF, BNP levels correlated with oxygen uptake (VO(2)), both at anaerobic threshold (VO(2)AT: r = -0.54, p < 0.001) and peak exercise (peak VO(2): r = -0.56, p < 0.001). Impairment of ventilatory efficiency (EqCO(2): r = 0.43, p < 0.001) and maximum exercise level (W % predicted: r = -0.44, p < 0.05) correlated less well with BNP. There was a significant inverse correlation between left ventricular ejection fraction and BNP (r = -0.50, p < 0.05). Brain natriuretic peptide discriminated well chronic HF patients with a peak VO(2) <10 ml/min/kg (area under the receiver operating characteristic [ROC] 0.93) or <14 ml/min/kg (area under the ROC 0.72). A BNP >316 pg/ml was associated with a risk ratio of 6.8 (95% confidence interval, 2.3 to 19.8) for a reduced exercise capacity with a peak VO(2) <14 ml/min/kg.

CONCLUSIONS

Brain natriuretic peptide is clearly associated with exercise capacity in chronic HF. Brain natriuretic peptide levels show a significant correlation with the impairment of VO(2) at peak exercise and anaerobic threshold. Brain natriuretic peptide is able to differentiate between chronic HF patients with moderately and severely impaired exercise capacity.

The impact of B-type natriuretic peptide levels on the diagnoses and management of congestive heart failure

Congestive heart failure poses significant challenges to physicians with both diagnosis and management. B-type natriuretic peptide (BNP) is synthesized in the cardiac ventricles. It correlates with ventricular function, NYHA classification, and prognosis. It is extremely useful in the emergency department in patients presenting with acute dyspnea. It has a particularly strong negative predictive value. In addition, it should be important in screening patients for heart diease, either for those who are at high risk (chemotherapy, diabetes) or as a possible screen before echocardiography. In the future, BNP may be used to modulate treatment of patients in the decompensated setting as well as in titrating outpatient therapy.

Natriuretic peptide system in fetal heart and circulation

Atrial natriuretic peptide, brain natriuretic peptide and C-type natriuretic peptide belong to a family of hormones that have diuretic, natriuretic and vasodepressor activity and play a part in pressure and volume homeostasis in adults. As little is known about the natriuretic peptides during cardiac maturation, this review summarizes current knowledge about the early expression of components of the natriuretic peptide system in the heart during embryonic and fetal development. The data indicate a functional importance of the fetal natriuretic peptide system, especially under pathophysiological conditions. Thus, in the fetus, the system fulfils important beneficial compensatory roles in cardiovascular disease, rather than in day-to-day pressure and volume homeostasis. In comparison with data on the relevance of natriuretic peptides in adults, those summarized here indicate a functional maturation of the natriuretic peptide system during ontogeny in mammals.

Utility of a rapid B-natriuretic peptide assay in differentiating congestive heart failure from lung disease in patients presenting with dyspnea

OBJECTIVES

Since B-type natriuretic peptide (BNP) is secreted by the left ventricle (LV) in response to volume elevated LV pressure, we sought to assess whether a rapid assay for BNP levels could differentiate cardiac from pulmonary causes of dyspnea.

BACKGROUND

Differentiating congestive heart failure (CHF) from pulmonary causes of dyspnea is very important for patients presenting to the emergency department (ED) with acute dyspnea.

METHODS

B-natriuretic peptide levels were obtained in 321 patients presenting to the ED with acute dyspnea. Physicians were blinded to BNP levels and asked to give their probability of the patient having CHF and their final diagnosis. Two independent cardiologists were blinded to BNP levels and asked to review the data and evaluate which patients presented with heart failure. Patients with right heart failure from cor pulmonale were classified as having CHF.

RESULTS

Patients with CHF (n = 134) had BNP levels of 758.5 +/- 798 pg/ml, significantly higher than the group of patients with a final diagnosis of pulmonary disease (n = 85) whose BNP was 61 +/- 10 pg/ml. The area under the receiver operating curve, which plots sensitivity versus specificity for BNP levels in separating cardiac from pulmonary disease, was 0.96 (p < 0.001). A breakdown of patients with pulmonary disease revealed: chronic obstructive pulmonary disease (COPD): 54 +/- 71 pg/ml (n = 42); asthma: 27 +/- 40 pg/ml (n = 11); acute bronchitis: 44 +/- 112 pg/ml (n = 14); pneumonia: 55 +/- 76 pg/ml (n = 8); tuberculosis: 93 +/- 54 pg/ml (n = 2); lung cancer: 120 +/- 120 pg/ml (n = 4); and acute pulmonary embolism: 207 +/- 272 pg/ml (n = 3). In patients with a history of lung disease but whose current complaint of dyspnea was seen as due to CHF, BNP levels were 731 +/- 764 pg/ml (n = 54). The group with a history of CHF but with a current COPD diagnosis had a BNP of 47 +/- 23 pg/ml (n = 11).

CONCLUSIONS

Rapid testing of BNP in the ED should help differentiate pulmonary from cardiac etiologies of dyspnea.

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.

B-type natriuretic peptide levels: a potential novel "white count" for congestive heart failure

Finding a simple blood test to aid in the diagnosis and treatment of patients with congestive heart failure could have a favorable impact on the costs associated with the disease. B-type natriuretic peptide (BNP) is synthesized in the cardiac ventricles, and its level correlates with left ventricular pressure, amount of dyspnea, and the state of neurohormonal modulation, thus making peptide the first potential "white count" for heart failure. Data indicate that serial point-of-care testing of BNP should be helpful in patients presenting to urgent care clinics with dyspnea. BNP may also serve as a screen for patients referred for echocardiography. A low BNP level makes left ventricular dysfunction (both systolic and diastolic) highly unlikely. BNP may also provide an effective means of improving in-hospital management of patients admitted with decompensated congestive heart failure. In some cases, BNP level observations may obviate the need for invasive hemodynamic monitoring and, when 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 as well as in assessing the state of neurohormonal compensation of the patient.

Clinical relevance of cardiac natriuretic peptides measured by means of competitive and non-competitive immunoassay methods in patients with renal failure on chronic hemodialysis

Increased levels of cardiac natriuretic peptides in patients undergoing hemodialysis may be a marker of cardiomyopathy and in consequence may be suitable prognostic indicators for the risk of development of cardiac disease. We measured plasma levels of ANP, BNP, proANP(1-98) and proBNP(1-76)-related peptides with some competitive and non-competitive immunoassay methods in patients with renal failure on chronic hemodialysis in order to compare the analytical performances of these methods and to evaluate the clinical usefulness of each assay for patients with chronic renal failure. ANP and BNP values significantly decreased after hemodialysis (on average, ANP by 36% and BNP by 16%); while all proANP and proBNP values tended to increase, but only proANP(1-30) (by 14.4%) and Nt-proBNP (by 9.5%) significantly. Although significant correlations were found among all the circulating levels of cardiac peptides studied, N-terminal pro-peptides correlated better among themselves than with ANP and BNP; ANP was only slightly correlated with all the other peptides, the only exception being BNP. Only BNP levels significantly increased according to the degree of ventricular hypertrophy and/or ventricular function in patients with chronic renal failure. The ANP assay is preferable in physiological and clinical studies for the rapid changes in atrial pre-load. BNP would be more useful in the follow-up of cardiac complications in patients with end-stage renal disease on regular hemodialysis. The assays of N-terminal proANP(1-98)-and proBNP(1-76)-related peptides proved to be of limited use, because they were not able to detect acute changes in pre-load during hemodialysis and were less useful than BNP levels as markers of ventricular hypertrophy and/or functional cardiac impairment.

Measurement of brain natriuretic peptide in plasma samples and cardiac tissue extracts by means of an immunoradiometric assay method

We evaluated the analytical characteristics and clinical usefulness of a commercial immunoradiometric assay (IRMA) kit for brain natriuretic peptide (BNP). Mean (+/-SD) plasma BNP concentrations measured in 129 normal subjects were 2.9+/-2.7 pmol/l (median 2.2 pmol/l; range 0.1-12.4 pmol/l). The mean (+/- SD) value observed in healthy men (2.1 +/- 2.0 pmol/l, n = 49) was significantly (p=0.0009) different to that found in women (3.4 +/- 2.9 pmol/l, n=80). A positive relationship (R=0.214, p=0.0174) was found between BNP values and age. In 65 patients with cardiac diseases, BNP levels increased with the progression of clinical severity of disease; patients with more severe disease [NYHA functional class III-IV, mean (+/- SD) BNP +/- 254 +/- 408 pmol/l, n=22] showed significantly (p<0.0001) increased values compared to patients with mild symptoms of disease (NYHA functional class I-II, mean (+/- SD) BNP=19.6 +/- 17.2 pmol/l, n=43). Furthermore, in 32 patients with chronic renal failure, greatly increased (p<0.0001) BNP values were found both before (mean +/- SD=88. 1+/- 111.1 pmol/l) and after haemodialysis (mean +/- SD=65.6 +/- 76.7 pmol/l), with a significant reduction after haemodialysis (p=0.0004) compared to pre-haemodialysis. The mean (+/- SD) BNP value found in atrial extracts collected during aorto-coronary bypass operations in 15 patients was 14.5 +/- 51.9 pmol/g of cardiac tissue. Moreover, the mean (+/- SD) tissue levels of BNP in 7 heart transplant recipients were 128.4 +/- 117.2 pmol/g of cardiac tissue in atrium, 68.4 +/- 76.7 pmol/g in ventricle, and 10.9 +/- 8.5 pmol/g in interventricular septum. Finally, BNP values found in cardiac tissues of two subjects collected at autopsy were considerably lower (on average 1/1000) than those observed in cardiac tissues of patients with cardiac diseases. The IRMA method for BNP determination evaluated in this study showed a good degree of sensitivity, precision and practicability. Therefore, this method should be a reliable tool for the measurement of plasma BNP levels for both experimental studies and routine assay.

Titration of vasodilator therapy in chronic heart failure according to plasma brain natriuretic peptide concentration: randomized comparison of the hemodynamic and neuroendocrine effects of tailored versus empirical therapy

BACKGROUND

Most patients with chronic heart failure (CHF) receive the same dose of angiotensin-converting enzyme (ACE) inhibitors because there is currently no measure of treatment efficacy. We sought to determine whether titration of vasodilator therapy according to plasma brain natriuretic peptide (BNP) concentration may be of value in the individual optimization of vasodilator therapy in CHF.

METHODS AND RESULTS

Twenty patients with mild to moderate CHF receiving stable conventional therapy including an ACE inhibitor were randomly assigned to titration of ACE inhibitor dosage according to serial measurement of plasma BNP concentration (BNP group) or optimal empirical ACE inhibitor therapy (clinical group) for 8 weeks. Only the BNP-driven approach was associated with significant reductions in plasma BNP concentration throughout the duration of the study and a significantly greater suppression when compared with empiric therapy after 4 weeks [-42.1% (-58.2, -19.7) vs -12.0% (-31.8, 13.8), P =.03]. Both treatment strategies were well tolerated and associated with favorable neurohormonal and hemodynamic effects; however, in comparison between groups, mean heart rate fell (P =.02) and plasma renin activity rose (P =.03) in the BNP group when compared with the clinical group.

CONCLUSIONS

Plasma BNP concentration may be chronically reduced by tailored vasodilator therapy in CHF. Furthermore, titration of vasodilator therapy according to plasma BNP was associated with more profound inhibition of the renin-angiotensin-aldosterone system and significant fall in heart rate when compared with empiric therapy.