N-terminal probrain natriuretic peptide (NT-proBNP) in the emergency diagnosis and in-hospital monitoring of patients with dyspnoea and ventricular dysfunction

Renal Function, Congestive Heart Failure, and Amino-Terminal Pro-Brain Natriuretic Peptide Measurement

The relationship between renal insufficiency and amino-terminal pro-brain natriuretic peptide (NT-proBNP) levels remains unclear. We examined this relationship in the context of patients who presented to the emergency department of an urban tertiary care medical center with dyspnea. Even in the presence of renal insufficiency, NT-proBNP remained a valuable tool for the diagnosis of acute congestive heart failure and it provides important prognostic information.

OBJECTIVES

We sought to examine the interaction between renal function and amino-terminal pro-brain natriuretic peptide (NT-proBNP) levels.

BACKGROUND

The effects of renal insufficiency on NT-proBNP among patients with and without acute congestive heart failure (CHF) are controversial. We examined the effects of kidney disease on NT-proBNP-based CHF diagnosis and prognosis.

METHODS

A total of 599 dyspneic patients with glomerular filtration rates (GFRs) as low as 14.8 ml/min were analyzed. We used multivariate logistic regression to examine covariates associated with NT-proBNP results and linear regression analysis to analyze associations between NT-proBNP and GFR. Receiver-operating characteristic analysis determined the sensitivity and specificity of NT-proBNP for CHF diagnosis. We also assessed 60-day mortality rates as a function of NT-proBNP concentration.

RESULTS

Glomerular filtration rates ranged from 15 ml/min/1.73 m2 to 252 ml/min/1.73 m2. Renal insufficiency was associated with risk factors for CHF, and patients with renal insufficiency were more likely to have CHF (all p < 0.003). Worse renal function was accompanied by cardiac structural and functional abnormalities on echocardiography. We found that NT-proBNP and GFR were inversely and independently related (p < 0.001) and that NT-proBNP values of > 450 pg/ml for patients ages <50 years and >900 pg/ml for patients > or =50 years had a sensitivity of 85% and a specificity of 88% for diagnosing acute CHF among subjects with GFR > or =60 ml/min/1.73 m2. Using a cut point of 1,200 pg/ml for subjects with GFR <60 ml/min/1.73 m2, we found sensitivity and specificity to be 89% and 72%, respectively. We found that NT-proBNP was the strongest overall independent risk factor for 60-day mortality (hazard ratio 1.57; 95% confidence interval 1.2 to 2.0; p = 0.0004) and remained so even in those with GFR <60 ml/min/1.73 m2 (hazard ratio 1.61; 95% confidence interval 1.14 to 2.26; p = 0.006).

CONCLUSIONS

The use of NT-proBNP testing is valuable for the evaluation of the dyspneic patient with suspected CHF, irrespective of renal function.

NT-proBNP testing for diagnosis and short-term prognosis in acute destabilized heart failure: an international pooled analysis of 1256 patients: the International Collaborative of NT-proBNP Study

AIMS

Experience with amino-terminal pro-brain natriuretic peptide (NT-proBNP) testing for evaluation of dyspnoeic patients with suspected acute heart failure (HF) is limited to single-centre studies. We wished to establish broader standards for NT-proBNP testing in a study involving four sites in three continents.

METHODS AND RESULTS

Differences in NT-proBNP levels among 1256 patients with and without acute HF and the relationship between NT-proBNP levels and HF symptoms were examined. Optimal cut-points for diagnosis and prognosis were identified and verified using bootstrapping and multi-variable logistic regression techniques. Seven hundred and twenty subjects (57.3%) had acute HF, whose median NT-proBNP was considerably higher than those without (4639 vs. 108 pg/mL, P<0.001), and levels of NT-proBNP correlated with HF symptom severity (P=0.008). An optimal strategy to identify acute HF was to use age-related cut-points of 450, 900, and 1800 pg/mL for ages <50, 50-75, and >75, which yielded 90% sensitivity and 84% specificity for acute HF. An age-independent cut-point of 300 pg/mL had 98% negative predictive value to exclude acute HF. Among those with acute HF, a presenting NT-proBNP concentration >5180 pg/mL was strongly predictive of death by 76 days [odds ratio=5.2, 95% confidence interval (CI)=2.2-8.1, P<0.001].

CONCLUSION

In this multi-centre, international study, NT-proBNP testing was valuable for diagnostic evaluation and short-term prognosis estimation in dyspnoeic subjects with suspected or confirmed acute HF and should establish broader standards for use of the NT-proBNP in dyspnoeic patients.

Role of N-terminal pro-B-type natriuretic peptide in risk stratification in patients presenting in the emergency room

BACKGROUND

Natriuretic peptides are promising markers in diagnosing acute and chronic heart failure and assessing prognosis in these patients. Increasing routine use to unselected patients is challenged by false-positive results. The aims of this study were to assess (a) the distributions of N-terminal B-type natriuretic peptide (NT-proBNP) values in various diagnostic groups, (b) factors that influence NT-proBNP, and (c) the value of NT-proBNP in risk stratification in unselected emergency room (ER) patients.

METHODS

NT-proBNP was measured in 876 unselected consecutive patients [mean (SD) age, 58 (18) years; 53% male] attending the ERs of 2 university hospitals and 1 community hospital. Diagnoses, age, sex, hemoglobin, creatinine (CREA), C-reactive protein (CRP), troponin T, and intensity of care were documented. In a subset consisting of all 417 patients at 1 center, in-hospital follow-up was completed with respect to a complicated clinical course, including intensive care treatment and death.

RESULTS

NT-proBNP was significantly increased in patients with cardiac diagnoses or histories compared with patients with only pulmonary or other diagnoses. In patients with other diagnoses, NT-proBNP values increased significantly with the number of atherosclerotic risk factors (P=0.044). Age, renal function, CRP, and to a much lesser extent, hemoglobin significantly influenced NT-proBNP values. The amount of care was positively correlated with NT-proBNP (P<0.001). Classification and regression tree analysis showed a superior impact of NT-proBNP for identification of high-risk patients.

CONCLUSIONS

NT-proBNP is a promising marker for identification of patients with structural heart disease in the ER and a suitable tool for risk stratification. Its use in the ER should be limited to clearly clinically defined patient groups at present to avoid a potential excess of additional diagnostic procedures in positive but asymptomatic patients.

B-type natriuretic peptide: Issues for the intensivist and pulmonologist

OBJECTIVE

B-type natriuretic peptide (BNP) and N-terminal pro-BNP (NT-proBNP), although promising as biomarkers for heart failure, are affected by multiple confounders. The purpose of this article is to review the literature on the utility of BNP and NT-proBNP as biomarkers, with a focus on their role in critical illness and pulmonary diseases.

DATA SOURCE

Published articles on BNP and NT-proBNP.

DATA ANALYSIS

Multiple disorders in the intensive care unit cause elevated BNP and NT-proBNP levels, including cardiac diseases, shock, pulmonary hypertension, acute respiratory distress syndrome, acute pulmonary embolism, chronic obstructive pulmonary disease, renal failure, and other conditions.

CONCLUSIONS

Intensivists and pulmonologists should understand that BNP and NT-proBNP levels might be raised to different degrees not only in heart failure but also in critical illness and various pulmonary diseases; in these situations, BNP and NT-proBNP may also serve as markers of severity and prognosis.

Effect of nesiritide in combination with standard therapy on serum concentrations of natriuretic peptides in patients admitted for decompensated congestive heart failure

OBJECTIVE

The objective of this study is to determine the effect of nesiritide (human recombinant BNP [hBNP]) in combination with standard therapy on the concentrations of B-type natriuretic peptide (BNP) and N-terminal probrain natriuretic peptide (NT-proBNP).

BACKGROUND

B-type natriuretic peptide is synthesized in cardiac ventricles as a prohormone (108 amino acids) and when released into peripheral circulation is cleaved into the active hormone BNP (amino acids 77-108) and an inactive amino terminal fragment NT-proBNP (amino acids 1-76).

METHODS

Three groups of patients with acutely decompensated congestive heart failure (CHF) received nesiritide for 24, 36, or 48 hours (n = 5, 7, and 7, respectively) in addition to standard therapy. Serial blood samples were collected. B-type natriuretic peptide and NT-proBNP were measured.

RESULTS

To correct for positive skew, natriuretic peptide concentrations were log transformed. The mean baseline (prenesiritide), 6-, 12-, and 24-hour infusion, and 6-, 12-, and 24-hour postinfusion concentrations of BNP were 1000, 2300, 2200, 1700, 580, 640, and 740 pg/mL, respectively (n = 19). The 6- and 12-hour postinfusion concentrations of BNP were significantly lower (< 0.05) than baseline. The mean baseline, 60-, 120-, and 24-hour infusion, and 6-, 12-, and 24-hour postinfusion concentrations of NT-proBNP were 6600, 6500, 5800, 4300, 4100, 4300, and 5100 pg/mL, respectively (n = 19). From the time point 24 hours after initiation of therapy through 12 hours postinfusion, the mean NT-proBNP concentration was significantly (< 0.05) lower than baseline.

CONCLUSION

Nesiritide, in combination with standard therapy, significantly lowered the endogenous concentrations of natriuretic peptides during infusion and after dosing was completed.

NT-ProBNP reduction percentage during admission for acutely decompensated heart failure predicts long-term cardiovascular mortality

BACKGROUND

N-terminal brain natriuretic peptide (NT-proBNP) improves emergency room diagnosis of acutely decompensated heart failure. Less evidence is available on the usefulness of NT-proBNP as a prognostic marker after hospitalization for acute heart failure. The percentage of NT-proBNP reduction during admission and its prognostic significance were studied.

METHODS AND RESULTS

This was a prospective study of 74 patients in the emergency department who were diagnosed with acute heart failure and who had follow-up evaluation for 6 and 12 months after admission. Plasma NT-proBNP concentrations were measured on admission, at 24 hours, at day 7, and at 6 and 12 months. Eighteen patients died during the 12-month follow-up; 12 deaths were from cardiovascular causes. NT-proBNP concentrations were significantly higher in the emergency department and at 24 hours than those concentrations that were found at day 7 and beyond (P < .001). During admission, the NT-proBNP concentration fell a mean of 15% in patients who died of cardiovascular causes during the 1-year follow-up evaluation, in 75% in those patients who died of non-cardiovascular causes, and in 50% in survivors (P = .004). The area under the receiver operator characteristic curve for NT-proBNP reduction percentage to predict cardiovascular death was 0.78 (95% CI, 0.66-0.90; P = .002). A 30% NT-proBNP reduction percentage cutoff value had 75% accuracy for the identification of high-risk patients and was the only variable that was associated with cardiovascular death in multivariate analysis (odds ratio, 4.4; 95% CI, 1.12-17.4; P = .03).

CONCLUSION

NT-proBNP reduction percentage during admission for acutely decompensated heart failure appeared to be the best predictor of cardiovascular death during the follow-up period. A <30% NT-proBNP reduction percentage identified a subgroup of high-risk patients.

NT-ProBNP in Outpatients After Myocardial Infarction: Interaction Between Symptoms and Left Ventricular Function and Optimized Cut-Points

BACKGROUND

N-terminal pro-brain natriuretic peptide (NT-proBNP) allows us to rule out left ventricular dysfunction (LVD) in the general population at a recommended cut-off concentration of 125 pg/mL. It was our objective to reassess this cut-point in outpatients after myocardial infarction.

METHODS AND RESULTS

NT-proBNP was assessed in 418 randomly selected outpatients who had experienced myocardial infarction and 352 siblings who had not experienced myocardial infarction (control). Left ventricular ejection fraction (LVEF) and mass-index (LVMI) were assessed by echocardiography. NT-proBNP was elevated in outpatients after myocardial infarction (mean [+/-SEM], 305 +/- 25 pg/mL vs control, 84 +/- 8 pg/mL; P < .01) and was correlated inversely with LVEF ( P < .001). When patients were stratified according to the presence or absence of heart failure, NT-proBNP was elevated significantly throughout all LVEF strata (each P < .05). On regression analysis, NT-proBNP was correlated independently with LVEF, LVMI, heart failure, and glomerular filtration rate (all P < .01). In patients with heart failure, the optimal cut-point for the detection of an LVEF <35% was 348 pg/mL (sensitivity 80%; specificity 69%) and for the detection of an LVEF <45% was 260 pg/mL (sensitivity 60%; specificity 60%). The relative risk for LVD in the presence of elevated NT-proBNP increased from 2.7 to 7.7 (EF < 35%) and from 1.4 to 2.4 (EF < 45%) when these cut-points were applied instead of the 125 pg/mL cut-point. An LVEF of <35% could be ruled out in symptomatic outpatients after myocardial infarction with a negative predictive value of 97% (cut-point 348 pg/mL) and in asymptomatic outpatients after myocardial infarction with a negative predictive value of 98% (cut-point 157 pg/mL).

CONCLUSION

NT-proBNP is higher in outpatients after myocardial infarction than in the general population. In symptomatic patients, a cut-point of 348 pg/mL yields satisfactory sensitivity and specificity for the detection of significant LVD (EF < 35%). Furthermore, significant LVD can be virtually ruled out in symptomatic and asymptomatic outpatients after myocardial infarction at below-threshold concentrations.

Elecsys NT-ProBNP and BNP Assays: Are There Analytically and Clinically Relevant Differences?

BACKGROUND

B-type natriuretic peptide (BNP; 77-108 amino acids) and its N-terminal (1-76 amino acids) counterpart, NT-proBNP, are cardiac biomarkers that have been established for the assessment of left ventricular dysfunction and congestive heart failure and provide prognostic and risk stratification information for patients with acute coronary syndrome. Various automated immunoassays currently are available for the measurement of these natriuretic peptides, but there are significant analytical differences, especially between BNP and NT-proBNP.

METHODS AND RESULTS

Recently published methods and results were reviewed.

CONCLUSION

Although there are significant pre-analytical and analytical differences between the Triage BNP and Elecsys NT-proBNP and other BNP methods, they do not translate to clinically significant differences in their diagnostic and prognostic application in the assessment of systolic heart failure and risk stratification of patients with acute coronary syndrome. However, there appears to be some evidence that suggests that NT-proBNP may have an advantage in the detection of patients with mild or asymptomatic heart disease.

Comparison of brain natriuretic peptide and probrain natriuretic peptide in the diagnosis of cardiogenic pulmonary edema in patients aged 65 and older

OBJECTIVES

Differentiating cardiogenic pulmonary edema (CPE) from respiratory causes of dyspnea is difficult in elderly patients. The aim of this study was to compare the usefulness of B-type natriuretic peptide (BNP) and amino-terminal fragment BNP (proBNP), to diagnose CPE in patients aged 65 and older.

DESIGN

Prospective study.

SETTING

Medical emergency department of a 2,000-bed urban teaching hospital.

PARTICIPANTS

Patients aged 65 and older presenting with acute dyspnea and a respiratory rate of 25 breaths/min or greater, a partial pressure of oxygen of 70 mmHg or less, or an oxygen saturation of 92% or less were included.

MEASUREMENTS

Rapid BNP and proBNP assays, performed blind at admission, were compared with the final diagnosis (CPE or no CPE) as defined by an expert team.

RESULTS

Two hundred two patients (mean age+/-standard deviation 80+/-9) were included; 88 (44%) had CPE. There was a strong correlation between proBNP and BNP values (correlation coefficient=0.91, P<.001). The median BNP and proBNP were higher in the group of patients with CPE (377 vs 74 pg/mL, P<.001, and 3,851 vs 495 pg/mL, P<.001, respectively). The best threshold values of BNP and proBNP were 250 pg/mL and 1,500 pg/mL, respectively. The area under the receiver operating characteristic curve was greater with BNP than with proBNP (0.85 vs 0.80, P<.05). BNP assay was more accurate in diagnosis than the emergency physician, whereas proBNP was not. Higher values of BNP and proBNP were associated with greater in-hospital mortality.

CONCLUSION

BNP assay is a more useful diagnostic indicator for CPE than proBNP in patients aged 65 and older.

The N-terminal Pro-BNP investigation of dyspnea in the emergency department (PRIDE) study

The utility of aminoterminal pro-brain natriuretic peptide (NT-proBNP) testing in the emergency department to rule out acute congestive heart failure (CHF) and the optimal cutpoints for this use are not established. We conducted a prospective study of 600 patients who presented in the emergency department with dyspnea. The clinical diagnosis of acute CHF was determined by study physicians who were blinded to NT-proBNP results. The primary end point was a comparison of NT-proBNP results with the clinical assessment of the managing physician for identifying acute CHF. The median NT-proBNP level among 209 patients (35%) who had acute CHF was 4,054 versus 131 pg/ml among 390 patients (65%) who did not (p <0.001). NT-proBNP at cutpoints of >450 pg/ml for patients <50 years of age and >900 pg/ml for patients >or=50 years of age were highly sensitive and specific for the diagnosis of acute CHF (p <0.001). An NT-proBNP level <300 pg/ml was optimal for ruling out acute CHF, with a negative predictive value of 99%. Increased NT-proBNP was the strongest independent predictor of a final diagnosis of acute CHF (odds ratio 44, 95% confidence interval 21.0 to 91.0, p <0.0001). NT-proBNP testing alone was superior to clinical judgment alone for diagnosing acute CHF (p = 0.006); NT-proBNP plus clinical judgment was superior to NT-proBNP or clinical judgment alone. NT-proBNP measurement is a valuable addition to standard clinical assessment for the identification and exclusion of acute CHF in the emergency department setting.

Recuento de hemosiderófagos en el esputo en el diagnóstico de la disnea de origen cardíaco

BACKGROUND AND OBJECTIVE

The respiratory or heart origin of dyspnea is not always easy to find out using the available diagnostic tools. Many patients present both heart and lung diseases that cause dyspnea. The role of hemosiderin-laden macrophages count (HC) in sputum in this context has not been well settled so far. The objective was to describe the prediction usefulness of HC in patients suffering from dyspnea of heart origin, and to find out if HC changed after administering treatment.

PATIENTS AND METHOD

HC was analyzed in 61 patients whose main symptom was dyspnea in the emergency department, and it was evaluated by means of clinical history, clinical course and performance of lung function tests and echocardiography.

RESULTS

35 patients were classified as having dyspnea of heart origin, 17 as having dyspnea of lung origin and 9 had dyspnea of both origins. The HC was higher in patients with dyspnea of heart origin 37% (95% CI, 26-47) or cardiopulmonary origin 30% (95% CI, 8-52) than in patients with dyspnea of lung origin 15% (95% CI, 4-27), and it remained higher despite administering treatment. The sensitivity (52%), specificity (88%), positive predictive value (92%) and negative predictive value (58%) was established for a 30% HC cutoff. The prediction model of heart origin dyspnea presented an area under the ROC curve of 0.978 (95% CI, 0.95-1).

CONCLUSIONS

HC reflects the severity of pulmonary venocapillar disturbance, identifies the majority of patients suffering from current or past heart failure or severe cardiac dysfunction, and is useful for the prediction of dyspnea of heart origin. HC utility should focus on selected patients.

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.

Natriuretic peptides BNP and NT-pro-BNP: established laboratory markers in clinical practice or just perspectives?

A growing body of literature describes diagnostic and prognostic value of B-type natriuretic peptides (BNP) in cardiac diseases since it was first described in 1988. As BNP is mainly secreted in the left ventricular (LV) myocardium, BNP was found to reflect LV function much better than any other neurohumoral factor. Thus, BNP is recommended as the first noninvasive blood test for determination of cardiac function by some authors. The introduction of fully automated, rapid bioassays for measurement of BNP and the aminoterminal part of its pro-hormone (NT-pro-BNP) made it possible to use the test even in emergency care settings. Here we review the literature with special focus on assessment of BNP and NT-pro-BNP in the following clinical settings: community screening for LV dysfunction, primary diagnosis of heart failure in general practice and emergency department (ED) and risk stratification in cardiac dysfunction and acute coronary syndromes. In addition, we discuss which applications can be recommended for daily clinical use from the cardiologist's point of view.

Science review: natriuretic peptides in critical illness

The present review will cover the mechanisms of release and the potential pathophysiological role of different natriuretic peptides in critically ill patients. By focusing on the cardiovascular system, possible implications of natriuretic peptides for diagnosis and treatment will be presented. In critical illness such as sepsis, trauma or major surgery, systemic hypotension and an intrinsic myocardial dysfunction occur. Impairment of the cardiovascular system contributes to poor prognosis in severe human sepsis. Natriuretic peptides have emerged as valuable marker substances to detect left ventricular dysfunction in congestive heart failure of different origins. Increased plasma levels of circulating natriuretic peptides, atrial natriuretic peptide, N-terminal pro-atrial natriuretic peptide, brain natriuretic peptide and its N-terminal moiety N-terminal pro-brain natriuretic peptide have also been found in critically ill patients. All of these peptides have been reported to reflect left ventricular dysfunction in these patients. The increased wall stress of the cardiac atria and ventricles is followed by the release of these natriuretic peptides. Furthermore, the release of atrial natriuretic peptide and brain natriuretic peptide might be triggered by members of the IL-6-related family and endotoxin in the critically ill. Apart from the vasoactive actions of circulating natriuretic peptides and their broad effects on the renal system, anti-ischemic properties and immunological functions have been reported for atrial natriuretic peptide. The early onset and rapid reversibility of left ventricular impairment in patients with good prognosis associated with a remarkably augmented plasma concentration of circulating natriuretic peptides suggest a possible role of these hormones in the monitoring of therapy success and the estimation of prognosis in the critically ill.