Impact of age and sex on plasma natriuretic peptide levels in healthy adults

Influence of history of heart failure on diagnostic performance and utility of B-type natriuretic peptide testing for acute dyspnea in the emergency department

BACKGROUND

The aim of this study was to assess the impact of a history of heart failure (HF) on emergency department (ED) B-type natriuretic peptide (BNP) testing and impact of feedback of BNP level to ED physicians.

METHODS

Admission BNP was measured in 143 patients (mean age 79 +/- 10 years) presenting to the ED with dyspnea. Emergency department physicians scored probability of HF as cause of dyspnea and categorized cause of dyspnea. An independent cardiologist determined cause of dyspnea after chart review. In 83 patients, ED physicians rescored and reclassified patients after BNP measurement and evaluated test utility.

RESULTS

The area under the receiver operating characteristic curve for BNP diagnosis of HF cause of dyspnea was significantly worse in patients with history of HF than those without (0.74 vs 0.94, P < .01) and in those with left ventricular ejection fraction <50% (0.64 vs 0.87, P < .05). A BNP cut point of 100 pg/mL had 100% sensitivity but only 41% specificity for diagnosing acute HF, whereas a cut point of 400 pg/mL had 87% sensitivity and 76% specificity. Emergency department physicians rated BNP useful in 64% of patients, and diagnostic uncertainty was reduced from 53% to 25% (P < .001).

CONCLUSION

B-type natriuretic peptide test performance for diagnosis of dyspnea cause is significantly reduced in patients with a history of HF and must be taken into consideration in the evaluation of such patients in the ED.

Angiotensin II receptor antagonist attenuates expression of aging markers in diabetic mouse heart

BACKGROUND

Diabetes mellitus is an independent risk factor for heart failure. Diabetes mellitus causes other age-related cardiovascular diseases. We assessed the hypothesis that hearts from diabetic animals are associated with accelerated aging processes. We also examined the effect of an angiotensin II receptor blocker (ARB) on the expression of senescence-associated molecules.

METHODS AND RESULTS

We administered an ARB (candesartan 10 mg/kg per day) or saline to diabetic db/db or control db/+ mice. The treatment was started when mice were 10-weeks-old, and continued for 15 weeks. Systolic function was impaired in db/db mice and candesartan improved cardiac function. The amount of phosphorylated Akt and S6 was decreased in saline-treated db/db mice, and candesartan treatment partially preserved phosphorylation. The amount of p21, p27, p53 or Rb was increased in the heart tissue of saline treated db/db mice. Candesartan treatment completely suppressed the increases of p21, p27, p53 and Rb.

CONCLUSIONS

An ARB improved cardiac function of diabetic animals, and this was accompanied by decreases of senescence-associated molecules in the myocardium. ARB may be a modality for heart failure patients with diabetes mellitus.

N-terminal Pro B-type Natriuretic Peptide Levels: Correlation with Echocardiographically Determined Left Ventricular Diastolic Function in an Ambulatory Cohort

OBJECTIVES

To investigate the correlations of plasma N-terminal pro B-type natriuretic peptide (NT-proBNP) levels with echocardiographic measurements of left ventricular (LV) systolic and/or diastolic function.

BACKGROUND

Plasma levels of NT-proBNP are increased in heart failure. The extent to which NT-proBNP levels increase in LV diastolic dysfunction has not been well characterized.

METHODS

Plasma NT-proBNP levels were measured in 191 consecutive, clinically stable, ambulatory patients. Echocardiography was used to determine LV systolic (LV ejection fraction [LVEF]) and diastolic function by mitral E wave to Doppler tissue early diastolic lateral annulus velocity ratio (E/Em). Patients with a history, physical findings, and/or echocardiographic evidence of cardiovascular disease (n = 148) were grouped as: (1) normal LV systolic function (LVEF > or = 55%, n = 81); and (2) LV systolic dysfunction (LVEF < 55%, n = 67). They were compared to a group of healthy control subjects (n = 43). Multivariate regression analyses were used to determine significant correlations with plasma NT-proBNP levels.

RESULTS

NT-proBNP levels correlated negatively with LVEF (P < .001) and positively with E/Em (P = .001). Multivariate regression analysis demonstrated a significant correlation of NT-proBNP levels with LVEF (P < .001) and E/Em (P = .03).

CONCLUSIONS

In this clinically stable, ambulatory cohort of patients with cardiovascular disease and healthy control subjects, plasma NT-proBNP levels were significantly higher in those with LV systolic dysfunction and/or elevated filling pressures, independent of the effects of LV mass, renal function, and age. These results suggest that NT-proBNP levels may be a useful adjunct in the characterization of patients presenting with history and/or symptoms compatible with LV systolic and/or diastolic dysfunction.

Aortic Stiffness Is an Independent Determinant of B-Type Natriuretic Peptide in Patients with Coronary Artery Disease

Previous studies demonstrated that the B-type natriuretic peptide (BNP) level is high in some patients with coronary artery disease (CAD) despite a preserved left ventricular function, although the mechanism underlying this increase in patients with CAD has not been fully elucidated. Because aortic stiffness is greater in patients with CAD and increases with CAD severity, there is a possibility that an increased aortic stiffness in turn increases the elevation of the BNP level in patients with CAD. In this study, we measured BNP level and brachial-ankle pulse wave velocity (baPWV) in 134 patients with CAD, and evaluated the relationship between BNP and baPWV. The patients were classified on the basis of the quartiles of BNP level to identify the characteristics of patients with a high BNP level. baPWV was significantly greater in patients classified into the highest quartile of BNP level than in those classified into the other quartiles. Multivariate analysis demonstrated that baPWV and left ventricular ejection fraction independently correlated with BNP level. Logistic regression analysis demonstrated that the odds ratio for the highest quartile of BNP level increased with baPWV quartile. This association remained significant after adjustment for systolic and diastolic function. In conclusion, increased aortic stiffness possibly underlies the increase in the BNP level in patients with CAD.

Cardiovascular and metabolic effects of natriuretic peptides

Natriuretic peptides (NP) are essential in mammals to regulate blood volume and pressure. The functional roles of NP are not limited to natriuresis and diuresis. Several peripheral and central actions of the peptides have been characterized. Studies on transgenic mice have revealed their key function in the regulation of cardiomyocyte growth. Plasma NP levels increase in patients with cardiovascular disorders and heart failure. They represent useful clinical markers for clinicians to diagnose heart diseases. The recent discovery of their potent lipolytic action in adipose tissue is a breakthrough in cardiovascular medicine. This new function of NP in the regulation of lipid metabolism offers interesting questions in the field of obesity, diabetes and cardiovascular diseases. This review will briefly describe the effects of NP on the cardiovascular system and lipid metabolism.

Effects of volume and/or pressure overload secondary to congenital heart disease (tetralogy of fallot or pulmonary stenosis) on right ventricular function using cardiovascular magnetic resonance and B-type natriuretic peptide levels

The aim of this study was to analyze the effect of pressure and/or volume overload on right ventricular (RV) function and brain natriuretic peptide (BNP) levels in patients with surgically corrected congenital heart disease. Forty-two consecutive patients aged 17 to 57 years (median 30) with congenital heart disease (32 with tetralogy of Fallot and 10 with pulmonary stenosis) were examined. The RV systolic pressure was estimated using Doppler echocardiography. Cardiovascular magnetic resonance imaging was used to obtain the RV volumes, ejection fraction (EF) and corrected EF (cEF). Plasma BNP levels were determined by immunoradiometric assay. Patients were categorized as having volume overload when pulmonary regurgitation was > or =10% and pressure overload when the RV systolic pressure was >40 mm Hg. Patients with RV volume overload had a lower RVEF compared with patients with pressure overload (p = 0.02) and lower left ventricular EF (p <0.001). BNP was higher in patients with volume overload than in patients with pressure overload (p = 0.002). BNP correlated with pulmonary regurgitation, RVEF, RV cEF, and left ventricular EF. In linear regression analysis, RV cEF was an independent predictor for BNP, after adjustment for age. Without the parameter of RV cEF in the regression model, pulmonary regurgitation and RVEF were independently associated with BNP level, after adjustment for age. In conclusion, patients with RV volume overload had higher BNP levels and lower RV function than patients with RV pressure overload. BNP levels were independently associated with the degree of RV volume overload and RV function.

Screening for ventricular remodeling

Current guidelines emphasize the importance of preventing heart failure (HF) by targeting people with preclinical forms of the disease. Accordingly, there is considerable interest in identifying left ventricular (LV) remodeling, the fundamental substrate for HF, in asymptomatic individuals in the community. Increased LV mass and asymptomatic LV systolic and LV diastolic dysfunction are the remodeling phenotypes that could be potentially considered for population-wide screening. Plasma levels of natriuretic peptides (NP) have been extensively investigated for such screening purposes. However, a majority of investigations suggest that their performance characteristics are suboptimal for identifying LV remodeling phenotypes unless high-risk individuals (eg, older men with hypertension) are targeted. In general, the prevalence of LV systolic dysfunction in women is too low to justify screening. In recent reports, sequential screening strategies combining urine and plasma NP or plasma NP and hand-held portable echocardiography have been advocated as potential approaches to identify asymptomatic LV systolic dysfunction in a cost-effective manner. Additional studies are warranted to confirm these findings.

B-type natriuretic peptide in paediatric patients with congenital heart disease

AIMS

To examine the diagnostic value of B-type natriuretic peptide (BNP) plasma concentration in congenital heart disease.

METHODS AND RESULTS

BNP was measured in 288 consecutive patients (mean age 6.0 +/- 6.4 years) with left-to-right shunt, left or right heart obstruction, tetralogy of Fallot, functionally univentricular heart, or impaired left ventricular function and compared with age- and gender-specific normal values, and to haemodynamic and echocardiographic data. BNP increased with decreasing left ventricular shortening fraction (r = -0.80; P < 0.001). In patients with left-to-right shunt, BNP was increased (mean SDS +1.64; P < 0.001) and positively correlated (P < 0.001) to shunt volume (r = 0.66), systolic right ventricular pressure (r = 0.69), mean pressure of the pulmonary artery (r = 0.66), and pulmonary resistance (r = 0.59). There was no correlation between BNP and invasive pressure gradient or extent of ventricular hypertrophy in patients with left or right heart obstruction. In patients with tetralogy of Fallot, BNP was not significantly increased. Patients with functionally univentricular heart had elevated BNP plasma levels (mean SDS +1.39; P < 0.001) without decrease after volume unloading by cavopulmonary connection.

CONCLUSION

In children with congenital heart defects, plasma BNP correlates closely to ventricular function. BNP plasma levels do not reflect directly the extent of ventricular pressure or volume work, but mirror the impairment of the loaded ventricles. Normal BNP cannot exclude pathology, but reflects a compensated status of the heart.

Utility of brain natriuretic peptide (BNP) measurement in cardiovascular disease

Cardiac failure is a prevalent and costly condition in Western society. The ageing of the population, together with current medical options which improve, rather than eradicate heart failure, lead to the projection that this problem will increase substantially in the foreseeable future. The availability of a simple test to assist the diagnosis and effective management of heart failure would greatly assist the clinical approach to this problem. This review examines the physiological basis for the measurement of natriuretic peptides as markers of the presence or risk of heart failure. It considers its use in the hospital and non-hospital setting and examines the cost-effectiveness of current assays. It is possible that in future natriuretic peptides may offer a form of treatment for heart failure, but this is beyond the scope of this review. Nevertheless, the review highlights the potential benefits of this group of tests in the management of heart failure.

Amino-terminal pro-B-type natriuretic peptide and B-type natriuretic peptide in the general community: determinants and detection of left ventricular dysfunction

OBJECTIVES

This study sought to characterize factors influencing amino-terminal pro-B-type natriuretic peptide (NT-proBNP) and to evaluate the ability of NT-proBNP to detect left ventricular (LV) dysfunction in a large community sample.

BACKGROUND

Secretion of BNP increases in cardiac disease, making BNP an attractive biomarker. Amino-terminal proBNP, a fragment of the BNP prohormone, is a new biomarker. We evaluated factors influencing NT-proBNP in normal patients and compared the ability of NT-proBNP and BNP to detect LV dysfunction in a large community sample.

METHODS

Amino-terminal pro-BNP was determined in plasma samples of a previously reported and clinically and echocardiographically characterized random sample (n = 1,869, age > or =45 years) of Olmsted County, Minnesota.

RESULTS

In normal patients (n = 746), female gender and older age were the strongest independent predictors of higher NT-proBNP. Test characteristics for detecting an LV ejection fraction < or =40% or < or =50% were determined in the total sample with receiver operating characteristic curves. Amino-terminal pro-BNP had significantly higher areas under the curve for detecting an LV ejection fraction < or =40% or < or =50% than BNP in the total population and in several male and age subgroups, whereas areas were equivalent in female subgroups. Age- and gender-adjusted cutpoints improved test characteristics of NT-proBNP. Both assays detected patients with systolic and/or moderate to severe diastolic dysfunction to a similar degree, which was less robust than the detection of LV systolic dysfunction alone.

CONCLUSIONS

Amino-terminal pro-BNP in normal patients is affected primarily by gender and age, which should be considered when interpreting values. Importantly, in the entire population sample NT-proBNP performed at least equivalently to BNP in detecting LV dysfunction and was superior in some subgroups in detecting LV systolic dysfunction.

Clinical relevance of biological variation: the lesson of brain natriuretic peptide (BNP) and NT-proBNP assay

The clinical relevance of brain natriuretic peptide (BNP) and N-terminal (NT)-proBNP assays as a diagnostic tool and prognostic marker in patients with cardiovascular diseases has recently been confirmed. However, several studies demonstrated variation of intra-individual BNP concentrations of >30% (ranging from 30% to 50%) with reference change values at the 95% confidence interval (i.e., the estimated critical difference) ranging from 99% to 130% in healthy subjects and heart failure patients. According to this estimated confidence interval, only a great variation in plasma BNP levels should be considered significant in an individual patient (for example, a decrease of >50% or an increase of more than two-fold). Many recent clinical studies have demonstrated that BNP variations below this estimated critical difference could also have clinical relevance. Like the concentration of other neuro-hormones, levels of plasma BNP fluctuate widely and rapidly along with heart rhythm and blood pressure variations in response to physiological stimuli. However, biological variation of BNP should not be interpreted strictly as random fluctuation around a homeostatic set point, as assumed by the common model used in all studies on biological variation of BNP reported in the literature. These results cannot be directly transferred to clinical practice. While awaiting more accurate studies, we suggest that variations of plasma BNP three-fold greater than the analytical imprecision should be considered as potentially relevant from a physiological and clinical point of view.

Impact of atrial fibrillation on the diagnostic performance of B-type natriuretic peptide concentration in dyspneic patients: an analysis from the breathing not properly multinational study

OBJECTIVES

This study was designed to assess the diagnostic performance of B-type natriuretic peptide (BNP) in the diagnosis of acute congestive heart failure (CHF) in patients with permanent/paroxysmal atrial fibrillation (AF) presenting with acute dyspnea.

BACKGROUND

It is unknown to what extent AF affects the diagnostic performance of BNP in patients presenting with acute dyspnea.

METHODS

We studied 1,431 patients drawn from a cohort of patients (n = 1,586) with acute dyspnea who had BNP levels measured on arrival. Patients were prospectively classified according to the presence or absence of permanent/paroxysmal AF.

RESULTS

In total, 292 patients had permanent/paroxysmal AF. In patients without HF, permanent/paroxysmal AF was associated with significantly higher BNP levels (p = 0.001). Conversely, in patients with HF, BNP levels did not differ significantly between patients with and without AF (p = 0.533). A BNP cutoff value of 100 pg/ml had a specificity of 40% and 79% for the diagnosis of acute HF in patients with and without AF, respectively. The areas under the receiver-operating characteristic curves were 0.84 (95% confidence interval 0.78 to 0.89) and 0.91 (95% confidence interval 0.89 to 0.93) for patients with and without AF, respectively.

CONCLUSIONS

In patients without, but not in those with HF, the presence of AF is associated with higher circulating BNP levels, suggesting that a higher diagnostic threshold should be used in patients with AF.

B-Type Natriuretic Peptide Testing for Structural Heart Disease Screening: A General Population-Based Study

BACKGROUND

Several types of structural heart disease are important precursors for congestive heart failure or cardioembolic stroke. We have previously demonstrated that plasma B-type natriuretic peptide (BNP) measurement is useful for detection of structural heart disease in a multiphasic health screening setting. To extend our hypothesis to the general population, the utility of BNP testing for identifying structural heart disease was assessed in a general population and in subgroups divided by sex, age, and presence/absence of risk factors.

METHODS AND RESULTS

This cross-sectional cohort study measured plasma BNP concentrations in 993 randomly selected community-dwelling adults (mean age 58 years). All subjects underwent plasma BNP measurement and transthoracic echocardiography. Using prejudged criteria, 41 subjects were diagnosed to have some form of structural heart disease (mild left ventricular systolic dysfunction in 11, valvular heart disease in 9, hypertensive heart disease in 3, hypertrophic cardiomyopathy in 2, ischemic heart disease in 2, lone atrial fibrillation in 14). The utility of BNP testing was evaluated by receiver operating characteristic (ROC) analysis and by cost analysis for detection of 1 case within each subgroup of the cohort. Overall, the sensitivity and specificity of BNP testing for identification of structural heart disease were 61% and 92%, respectively. The area under the ROC curve was 0.77 (95% CI; 0.74-0.79). When sex-specific ROC analyses were performed, sensitivity and specificity were 61% and 91% in men, and 50% and 95% in women, respectively. Although the performance of BNP testing on the basis of these figures might be suboptimal, efficacy was improved in subgroups with a high prevalence of heart disease (>8%) such as the cohort aged > or =65 years (men, area under ROC curve = 0.88; cost <US $1400: women, area under ROC curve = 0.83; cost <US $3000) as well as the cohort having cardiovascular risk factors such as hypertension or diabetes (men, area under ROC curve = 0.85; cost <US $1700: women, area under ROC curve = 0.83; cost <US $3100).

CONCLUSION

The present results suggest that BNP testing for structural heart disease screening in community-based populations is useful for cohorts with a high prevalence of heart disease. However, its efficacy is reduced in cohorts with a low prevalence rate.

Relation of age, severity of illness, and hemodynamics with brain natriuretic peptide levels in patients <20 years of age with heart disease

Brain natriuretic peptide (BNP) levels were obtained before cardiac catheterization in 193 pediatric patients with a variety of cardiac lesions. Age and functional status had strong relations to BNP values, with elevations of BNP levels associated with increasing functional disability and decreasing age. Mild but statistically significant correlations were found between BNP levels and right-sided cardiac pressures. In patients with volume-overloaded ventricles, BNP correlated with the degree of overcirculation.

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.

Risk of cardiovascular death in elderly patients with possible heart failure. B-type natriuretic peptide (BNP) and the aminoterminal fragment of ProBNP (N-terminal proBNP) as prognostic indicators in a 6-year follow-up of a primary care population

Heart failure is common in the elderly population and carries a serious prognosis. We evaluated EDTA-plasma B-type natriuretic peptide (brain natriuretic peptide, BNP) and the aminoterminal fragment of proBNP (N-terminal proBNP) as prognostic markers in elderly primary care patients with symptoms of heart failure.

METHODS

From 474 patients attending primary care for symptoms of dyspnea, fatigue and/or peripheral edema, blood was sampled in plastic tubes containing EDTA to measure BNP by non-extraction immunoradiometric assay and N-terminal proBNP by non-extraction radioimmunoassay. Patients were evaluated with respect to history and function by NYHA classification and Doppler echocardiography. Follow-up time was 6 years. Cox regression analysis was performed to identify the weight of risk variables.

CONCLUSION

Total 6-year mortality was 20% (102 patients out of 510), and cardiovascular (CV) mortality was 14% (71 patients, 70% of total mortality). BNP and N-terminal proBNP were essentially equally useful as prognostic markers. In patients with the highest quartiles of plasma concentration of BNP and N-terminal proBNP, respectively, the risk of cardiovascular mortality was 10 and 4.8 times, respectively, higher than that in those in the lowest quartile. Peptide concentrations varied widely within all functional groups including those with normal echocardiographic findings. Plasma concentrations of BNP and N-terminal proBNP give important prognostic information concerning risk of cardiovascular mortality. Cost-effective "clinical pathways" should be outlined for patients with elevated peptide concentrations.

Obese subjects with heart failure have lower N-terminal pro-brain natriuretic peptide plasma levels irrespective of aetiology

N-terminal pro-brain natriuretic peptide (NT-proBNP) may be useful in the diagnosis of heart failure and ventricular dysfunction. Obesity is an independent cardiovascular risk factor. The purpose of this study was to measure NT-proBNP plasma levels in obese and non-obese subjects with heart failure and to compare levels in subjects with ischaemic and dilated aetiology. In this study, obese subjects had 63% lower NT-proBNP plasma levels than non-obese subjects (p < 0.01). In multivariate analysis, BMI was inversely associated with NT-proBNP plasma levels (p < 0.05) and a 17% decrease in natriuretic peptide levels was attributed to obesity (p < 0.036). When we analyzed data according to the aetiology of heart failure, we found that both groups (ischaemic and dilated) had a 65% decrease in NT-proBNP plasma levels in obese subjects compared to non-obese subjects.

Amino-terminal proCNP: a putative marker of cartilage activity in postnatal growth

Recent evidence from rodents and humans shows that C-type natriuretic peptide (CNP) plays an essential role in endochondral bone growth. We recently identified a stable product of proCNP, amino-terminal proCNP (NT-proCNP), which unlike CNP is readily measurable in human and ovine plasma. Hypothesizing that plasma NT-proCNP concentrations reflect in part CNP synthesis within growth plates of rapidly growing cartilage, we studied levels of CNP forms in both children and lambs and related these to age, growth velocity, and biochemical markers of bone turnover. Plasma NT-proCNP levels were elevated at birth and fell progressively with age. Significant associations between plasma NT-proCNP and height velocity, alkaline phosphatase, and type 1 collagen C telopeptide were identified in children (aged 5-18 y). In longitudinal animal studies, elevated plasma concentration of NT-proCNP in 1-wk-old lambs fell progressively to mature adult levels at age 27 wk. Plasma NT-proCNP showed a highly significant association with alkaline phosphatase and metacarpal growth velocity. Glucocorticoids, a treatment known to inhibit cartilage proliferation, reduced metacarpal growth elongation in 4-wk-old lambs and markedly lowered circulating NT-proCNP levels during the treatment period. In summary, NT-proCNP levels in blood show a strong association with growth velocity and markers of bone formation and may well serve as a useful marker of growth plate activity in humans and other mammals.

The Relationship Between B-type Natriuretic Peptide and Health Status in Patients With Heart Failure

BACKGROUND

Although B-type natriuretic peptide (BNP) levels have been proposed as a means of assessing disease severity in patients with heart failure, it is not known if BNP levels are correlated with health status (symptom burden, functional limitation, and quality of life).

METHODS AND RESULTS

We studied 342 outpatients with systolic heart failure from 14 centers at baseline and 6 +/- 2 weeks with BNP levels and the Kansas City Cardiomyopathy Questionnaire (KCCQ), a heart-failure-specific health status instrument. We assessed the correlation between KCCQ scores and BNP at baseline and changes in KCCQ according to changes in BNP levels between baseline and follow-up. Mean baseline BNP levels were 379 +/- 387 pg/mL and mean KCCQ summary scores were 62 +/- 23 points. Although baseline BNP and KCCQ were both associated with New York Heart Association classification (P < .001 for both), BNP and KCCQ were not correlated (r(2) = 0.008, P = .15). There was no significant relationship between changes in BNP and KCCQ regardless of the threshold used to define a clinically meaningful BNP change. For example, using >50% BNP change threshold, KCCQ improved by 3.7 +/- 14.2 in patients with decreasing BNP, improved by 1.7 +/- 13.6 in patients with no BNP change, and improved by 1.0 +/- 13.4 in patients with increasing BNP (P = .6).

CONCLUSION

BNP and health status are not correlated in outpatients with heart failure in the short term. This suggests that these measures may assess different aspects of heart failure severity, and that physiologic measures do not reflect patients' perceptions of the impact of heart failure on their health status.

B-type natriuretic peptide as a biomarker beyond heart failure: speculations and opportunities

Cardiac secretion of B-type natriuretic peptide (BNP) Increases with the progression of heart failure (HF), and plasma measurement of BNP has emerged recently as a useful, cost-effective biomarker for the diagnosis and prognosis of HF. The diagnostic utility of BNP is complemented by its therapeutic use in decompensated HF. Although clinical use of BNP as a biomarker in HF is Increasing, the specificity of BNP for HF is not robust, suggesting that other mechanisms beyond simple ventricular stretch stimulate BNP release. Several studies have shown that BNP levels Increase in other cardiovascular disease states including ischemia, arrhythmias, fibrosis, cardiac hypertrophy, and coronary endothelial dysfunction. Furthermore, 2 important studies revealed recently that moderate elevations In BNP level, well below the HF range, have prognostic value for future cardiovascular events. Specifically, BNP levels greater than 20 pg/mL were associated with significantly Increased risk of HF and atrial fibrillation. These observations increase speculation that elevated BNP levels represent a final common pathway for many cardiovascular pathologic states and that BNP can be used as a biomarker for non-HF mechanisms, preclinical disease, and other pathologic states of myocardial disease.

What is the normal range for N-terminal pro-brain natriuretic peptide? How well does this normal range screen for cardiovascular disease?

AIMS

To define the N-terminal pro-brain natriuretic peptide (NTpBNP) normal range, assessing its cardiovascular screening characteristics in general population and higher risk subjects.

METHODS AND RESULTS

A total of 2320 subjects (1392 general population and 928 high-risk) > or =45 years old, selected randomly from seven community practices, were invited to undergo clinical assessment and echocardiography and to assess NTpBNP serum levels. Of these, 1205 attended. The NTpBNP normal range was calculated and its cardiovascular screening characteristics were assessed. Age (P<0.0001) and female gender (P<0.0001) independently predicted NTpBNP levels in normal subjects. In the general population, age- and gender-stratified normal NTpBNP levels gave a negative-predictive value (NPV) of 99% in excluding left ventricular systolic dysfunction, atrial fibrillation, and valvular heart disease, and a positive predictive value of 56% in detecting any cardiovascular disease assessed. In high-risk subjects, these values were 98 and 62%, respectively. Ninety-five per cent of subjects with NTpBNP levels over four times the normal had significant cardiovascular disease with the others having renal dysfunction.

CONCLUSION

Normal NTpBNP levels should be stratified by age and gender. Normal NTpBNP levels give high NPV in excluding significant cardiovascular disease. Most subjects with raised NTpBNP levels and almost all subjects with NTpBNP levels over four times the normal have significant cardiovascular disease.

The use of B-type natriuretic peptide in the management of elderly patients with acute dyspnoea

OBJECTIVES

The aim of this study was to define the impact of B-type natriuretic peptide (BNP) levels on the management of elderly patients presenting with acute dyspnoea.

DESIGN

We performed a prospective randomized controlled study in 269 elderly patients at least 70 years of age included in the B-type natriuretic peptide for Acute Shortness of breath Evaluation (BASEL) study. Patients were randomly assigned to a diagnostic strategy with (n = 136, BNP group) or without (n = 133, control group) the use of BNP levels provided by a rapid bedside assay. The time to discharge and the total cost of treatment were the primary end-points.

RESULTS

Amongst elderly patients, baseline characteristics were well matched between both groups. The use of BNP levels significantly reduced the time to discharge (median 9.0 in the BNP group versus 11.0 days in the control group; P = 0.029). Total treatment cost was $5381 (95% CI, 4482-6280) in the BNP group when compared with $7411 (95% CI, 6180-8642; P = 0.009) in the control group. In addition, a significant reduction in 30-day mortality was observed (9% in the BNP group versus 17% in the control group; P = 0.039).

CONCLUSIONS

Used in conjunction with other clinical information, rapid measurement of BNP in the emergency department improved the management of elderly patients presenting with acute dyspnoea and thereby reduced the time to discharge and the total treatment cost. In addition, BNP testing seemed to reduce 30-day mortality.

Blood haemoglobin is an independent predictor of B-type natriuretic peptide (BNP)

BNP (B-type natriuretic peptide) and anaemia are both associated with adverse outcome in patients with chronic heart failure. Whether low haemoglobin levels are independently predictive of elevated BNP levels in subjects without heart failure is unknown. In the present study, we examined the relationship between haemoglobin and BNP levels in 234 patients with suspected coronary heart disease without a history of chronic heart failure, adjusting for known predictors of BNP levels. By univariate analysis, haemoglobin levels were inversely related to logarithmically transformed BNP values (r=−0.30, P<0.0001). After adjustment for patient age, gender, body mass index, history of myocardial infarction, use of diuretics, angiotensin-converting enzyme inhibitors and β-blockers, estimated creatinine clearance rate, extent of coronary disease, left ventricular ejection fraction and left ventricular end-diastolic pressure, blood haemoglobin remained an independent predictor of plasma BNP (standardized β-coefficient=−0.253, P<0.0001). A similar relationship was observed between haematocrit and BNP (standardized β-coefficient −0.215, P<0.0001). We conclude that haemoglobin levels are independently predictive of plasma BNP levels in patients with suspected coronary heart disease without heart failure. Anaemia may contribute to elevated BNP levels in the absence of heart failure, and may represent an important confounder of the relationship between BNP, cardiac function and prognosis.

Predictors of Elevated B-Type Natriuretic Peptide Concentrations in Dyspneic Patients Without Heart Failure: An Analysis From the Breathing Not Properly Multinational Study

STUDY OBJECTIVE

B-type natriuretic peptide (BNP) is an established tool for the diagnosis of acute congestive heart failure in patients presenting with dyspnea. Some patients have moderately elevated BNP levels (ie, 100 to 500 pg/mL) in the absence of acute congestive heart failure. The objective of the current study was to identify independent predictors of elevated BNP concentrations in the absence of congestive heart failure.

METHODS

We studied 781 patients without acute congestive heart failure and BNP levels 0 to 500 pg/mL drawn from a cohort of 1,586 patients with acute dyspnea who had BNP levels measured on emergency department arrival. Two cardiologists blinded to BNP results reviewed all clinical data and categorized patients according to whether they had acute congestive heart failure or not.

RESULTS

Independent predictors of elevated BNP levels (ie, >100 pg/mL) were a medical history of atrial fibrillation, radiographic cardiomegaly, decreased blood hemoglobin concentration, decreased body mass index, and increased age.

CONCLUSION

Knowledge of these commonly obtained variables should aid clinicians in the interpretation of moderately elevated BNP results in patients presenting with acute dyspnea in the emergency department.

Early brain natriuretic peptide increase reflects acute myocardial ischemia in patients with ongoing chest pain

BACKGROUND

Plasma brain natriuretic peptide levels increase during acute ischemic events. In this study we tested the diagnostic performance of brain natriuretic peptide measurements in the detection of acute myocardial ischemia.

METHODS

Blood brain natriuretic peptide was measured in 101 patients with ongoing chest pain but no heart failure or an ST-segment elevation myocardial infarction on arrival at the emergency department (baseline) and at 2 and 6 h later. After diagnostic testing and 1-month follow-up for ischemia, patients were classified as either ischemic or non-ischemic.

RESULTS

In the ischemic group median (25th, 75th percentiles) brain natriuretic peptide values (pg/ml) were 122 (20, 349) at baseline, 116 (36, 347) at 2 h, increasing to 148 (52, 428) at 6 h (p<0.001 vs. baseline). Non-ischemic patients had 12 (5, 32) at baseline, 9 (6, 30) at 2 h, and 13 (5, 29) at 6 h (p<0.001 vs. corresponding values of the ischemic group). Receiver operator characteristic curves were constructed for brain natriuretic peptide values at baseline 2 and 6 h and for the increase of peptide levels from baseline to 6 h. All areas under curve indicated a significant diagnostic ability for the detection of ischemia. The 6-h measurement had better diagnostic performance than baseline and 2-h measurements. The subgroup of ischemic patients without myocardial necrosis also had higher brain natriuretic peptide values and could thus be discriminated from non-ischemic subjects.

CONCLUSIONS

Brain natriuretic peptide values may detect acute myocardial ischemia in patients with ongoing chest pain but without ST-segment elevation, and distinguish ischemic patients from those with pain of non-ischemic origin.

Effect of body mass index on natriuretic peptide levels in patients with acute congestive heart failure: a ProBNP Investigation of Dyspnea in the Emergency Department (PRIDE) substudy

BACKGROUND

Obesity is associated with lower B-type natriuretic peptide (BNP) levels in healthy individuals and patients with chronic congestive heart failure (CHF). Neither the mechanism of natriuretic peptide suppression in the obese patient nor whether obesity affects natriuretic peptide levels among patients with acute CHF is known.

METHODS

The associations of amino-terminal pro-BNP (NT-proBNP), BNP, and body mass index (BMI) were examined in 204 subjects with acute CHF. Multivariable regression analyses were performed to identify factors independently related to NT-proBNP and BNP levels.

RESULTS

Across clinical strata of normal (<25 kg/m2), overweight (25-29.9 kg/m2), and obese (> or =30 kg/m2) patients, median NT-proBNP and BNP levels decreased with increasing BMI (both P values < .001). In multivariable analyses adjusting for covariates known to affect BNP levels, the inverse relationship between BMI and both NT-proBNP and BNP remained ( P < .05 for both). Using a cut point of 900 pg/mL, NT-proBNP was falsely negative in up to 10% of CHF cases in overweight patients (25-29.9 kg/m2) and 15% in obese patients (> or =30 kg/m2). Using the standard cut point of 100 pg/mL, BNP testing was falsely negative in 20% of CHF cases in both overweight and obese patients. The assays for NT-proBNP and BNP exhibited similar overall sensitivity for the diagnosis of CHF.

CONCLUSIONS

When adjusted for relevant covariates, compared with normal counterparts, overweight and obese patients with acute CHF have lower circulating NT-proBNP and BNP levels, suggesting a BMI-related defect in natriuretic peptide secretion. NT-proBNP fell below the diagnostic cutoff for CHF less often than BNP in overweight and obese individuals; however, when used as a diagnostic tool to identify CHF in such patients, both markers may have reduced sensitivity.

Using BNP to develop a risk score for heart failure in primary care

AIMS

Chronic heart failure is a common condition with high mortality. Accurate diagnosis in primary care is difficult. Elevated B-type natriuretic peptide (BNP) is associated with left ventricular systolic dysfunction and increased mortality. Prognostic scoring systems using BNP may help to stratify risk in primary care patients. The aim of this research was to establish the independent variables which predict mortality in a primary care population-prescribed loop diuretics and to generate and validate a scoring system for heart failure in general practice.

METHODS AND RESULTS

Five hundred and thirty-two patients were followed up for a mean of 6.4 years after attending a research clinic for clinical assessment, electrocardiogram (ECG), echocardiography, and BNP. Multivariate analysis was used to establish independent prognostic variables and to generate a prognostic scoring system. The score generated was [0.50 x BNP+5 x age+50 x (CVA+sex+diabetes+ECG)]. The cut-off scores for risk groups were; 25th percentile, 411; 50th percentile, 475; 75th percentile, 524; Harrell's c=0.75.

CONCLUSION

Developing prognostic scoring systems provides a means of risk stratifying patients without relying on a single cut-off diagnostic value for BNP. Further validation of such scoring systems may improve future management of community heart failure patients.

Nt-proANP in plasma, a marker of salt sensitivity, is reduced in type 2 diabetes patients

OBJECTIVE

We recently showed that plasma concentration of N-terminal atrial natriuretic peptide (Nt-proANP) is strongly directly related to salt sensitivity. The aims of the present study were to test (i) whether plasma concentration of N-terminal brain natriuretic peptide (Nt-proBNP) is related to salt sensitivity and (ii) whether Nt-proANP, as a marker of salt sensitivity, differs between type 2 diabetes patients and nondiabetic subjects without a history of coronary heart disease.

METHODS

Nt-proBNP was determined in 30 Swedish normal subjects with heredity for primary hypertension and salt sensitivity was defined as the difference between mean arterial blood pressure after 1 week on a high-salt diet (240 mmol day(-1)) and 1 week on a low-salt diet (10 mmol day(-1)). Nt-proANP was measured in 253 patients with type 2 diabetes and in 230 nondiabetic subjects aged 40-70 years, all without a history of coronary heart disease.

RESULTS

Amongst the 30 subjects, in whom salt sensitivity was directly measured, Nt-proBNP was not correlated with salt sensitivity (R=-0.18, P=0.35). Nt-proANP (median, interquartile range) was lower in patients with type 2 diabetes (505, 387-661 pmol L(-1)) than in nondiabetic subjects (536, 421-696 pmol L(-1)) (P=0.02). In a multiple regression analysis heart rate (P <0.00001), diastolic blood pressure (P=0.02) and diabetes status (P=0.02) were inversely related whereas age (P <0.00001), cystatin C (P=0.0006), hypertension treatment (P=0.002) and female sex (P=0.006) were directly related to ln(Nt-proANP).

CONCLUSION

In contrast to Nt-proANP, Nt-proBNP is not related to salt sensitivity. Salt sensitivity, as estimated by Nt-proANP, seems to be reduced in type 2 diabetes.

Single assay for amino-terminal fragments of cardiac A- and B-type natriuretic peptides

BACKGROUND

High circulating concentrations of N-terminal fragments of A- and B-type natriuretic peptides (NT-proANP and NT-proBNP) identify patients with impaired cardiac function. ProANP-derived peptides are particularly sensitive to increased preload of the heart and proBNP-derived peptides to increased afterload; therefore, combining the information from the ANP and BNP systems into a single analyte could produce an assay with increased diagnostic and prognostic power.

METHODS

We prepared a hybrid peptide containing peptide sequences from both NT-proBNP and NT-proANP (referred to as NT-proXNP) by recombinant techniques and used it to develop a RIA combining weighed concentrations of NT-proANP and NT-proBNP into a new virtual analyte, NT-proXNP. We used the novel method to measure the circulating concentrations in healthy persons and in patients with cardiac disorders. We also characterized the assay by HPLC analysis of the immunoreactive molecular forms in human plasma and serum.

RESULTS

The results from the novel assay correlated well with independent home-made NT-proANP and NT-proBNP assays (r2 = 0.75-0.85) as well with the arithmetic sum of NT-proANP and NT-proBNP (r2 = 0.92). Patients with valvular heart disease (VHD) and coronary artery disease (CAD) had significantly increased NT-proXNP concentrations. The areas under the curve (AUC) of the NT-proXNP assay in detecting VHD and CAD (0.961 and 0.924, respectively) were significantly larger than the AUC of either NT-proANP (0.947 and 0.872) or NT-proBNP (0.913 and 0.782) assays. HPLC analysis showed that the novel NT-proXNP assay detects two major classes of circulating immunoreactivity corresponding to peptides derived from NT-proANP and NT-proBNP.

CONCLUSIONS

Our novel immunoassay mimics the physiologic signaling system working in the body by converging the information obtained from the activation of ANP and BNP into a single virtual analyte, NT-proXNP. It appears to have a diagnostic efficiency equal to or slightly better than that of individual NT-proANP or NT-proBNP assays.

The extent of myocardial damage assessed by contrast-enhanced MRI is a major determinant of N-BNP concentration after myocardial infarction

AIMS

To evaluate the relationship between N-terminal Pro-Brain Natriuretic Peptide (N-BNP) level and contrast-enhanced MRI in patients after acute myocardial infarction (MI).

METHODS

Eighty-two patients were studied. Venous blood samples were obtained 3 days after MI and MRI was performed from 2 to 7 days after MI, with determination of left ventricular function and acquisition of perfusion data after injection of gadolinium-DTPA. First-pass images (FPI) and Delayed contrast-enhanced (CE) images were analyzed using a 17-segment model, and the extent of transmurality was determined by a visual score.

RESULTS

Univariate analysis showed that age (P<0.001), sex (P<0.02), Left Ventricular Ejection Fraction (LVEF) <45% (P<0.002), creatinine (P<0.05) and delayed CE-MR images (P<0.006) were predictors of a supramedian N-BNP level. FPI was not a predictor in this univariate analysis (P<0.078). In a multivariate model, only age, LVEF <45% and delayed CE-MRI were associated with an increased N-BNP level.

CONCLUSION

After MI, high N-BNP levels are dependent on the LVEF but also on the myocardial infarct size derived from the delayed CE-MR images.

Influence of age on natriuretic peptides in patients with chronic heart failure: a comparison between ANP/NT-ANP and BNP/NT-proBNP

BACKGROUND

Natriuretic peptides are currently used in the diagnosis and follow-up of patients with Chronic Heart Failure (CHF). However, it is unknown whether there are different influences of age on atrial natriuretic peptide (ANP)/N-terminal-ANP (NT-ANP) or B-type natriuretic peptide (BNP)/N-terminal-proBNP (NT-proBNP).

AIMS

To compare the influence of age and gender on plasma levels of ANP/NT-ANP and BNP/NT-proBNP in CHF patients.

METHODS AND RESULTS

Natriuretic peptides were measured in 311 CHF patients (68+/-8 years, 76% males, left ventricular ejection fraction (LVEF) 0.23+/-0.08). All natriuretic peptides were significantly related to age (p<0.05) on multivariate regression analysis, with partial correlation coefficients of 0.18, 0.29, 0.28 and 0.25 for ANP, NT-ANP, BNP and NT-proBNP, respectively. The relative increase of both BNP/NT-proBNP were more pronounced than of ANP/NT-ANP (p<0.01). Furthermore, the relative increase of BNP with age was markedly larger than of NT-proBNP (p<0.01). Levels of all natriuretic peptides were also significantly related to cardiothoracic ratio, renal function and LVEF.

CONCLUSION

In patients with CHF, BNP/NT-proBNP were more related to age than ANP/NT-ANP, and BNP was more related to age than NT-proBNP. However, in these CHF patients the influence of age on the levels of all natriuretic peptides was modest, and comparable to several other factors.

Plasma B-type Natriuretic Peptide Levels and Risk Factors for Congestive Heart Failure in a Japanese General Population

This cross-sectional study was performed to establish the rationale for BNP testing for identifying subjects at high risk of congestive heart failure (CHF) in a screening setting. Plasma BNP concentrations were measured in 8,178 community-dwelling residents (mean age, 62 +/- 12 years; 3,194 males). First, in order to determine age- and sex-related reference values for plasma BNP levels, subjects having factors known to influence plasma BNP levels were excluded. The remaining 3,410 subjects were eligible for the reference study. Second, to verify BNP testing for screening for subjects at high risk of CHF, the clinical characteristics of subjects showing abnormally high plasma BNP levels (> or = 97.5 percentile for each age- and sex-specific value of the reference cohort) were examined. In the reference subjects, plasma BNP levels increased with age in both genders, and were higher in women than in men. In the original cohort, age- and sex-specific reference values for high plasma BNP levels were related to the presence of major ECG abnormalities, hypertension, mildly elevated serum creatinine levels, and a history of coronary heart disease. The results of the present study indicate that individuals with high plasma BNP levels in the community have accumulating risk factors for CHF. This suggests that plasma BNP measurement may be a useful screening test for identification of individuals at high risk of CHF within a Japanese general population.

Comparison of Positive Cases for B-type Natriuretic Peptide and ECG Testing for Identification of Precursor Forms of Heart Failure in an Elderly Population

Plasma B-type natriuretic peptide (BNP) levels have been reported to be elevated in various types of cardiac disorders and in precursors of CHF. To elucidate the potential ability of BNP testing to identify individuals with structural cardiac disease (ie, hypertensive heart disease, coronary heart disease, valvular heart disease) among community-dwelling elderly persons, cases which were positive on BNP testing were compared to those positive on ECG testing. In the initial phase, we performed plasma BNP measurements and ECG in 856 participants (age > or = 65 years) selected from a general population. From within this group, subjects with an abnormal ECG (n = 125) were selected according to the Minnesota code. Subjects with elevated BNP were selected independently on the basis of plasma levels (n = 112). In the next phase, subjects in both groups were invited to complete Rose's angina questionnaire and to undergo physical examination and transthoracic echocardiography. In this subject group (positive in ECG testing and/or BNP testing), the two tests had comparable sensitivity (65% versus 59%: NS) and specificity (40% versus 41%: NS) for identifying hypertensive heart disease (n = 17). For coronary heart disease (n = 12), the two tests had also comparable sensitivity (58% versus 42%: NS) and specificity (39% versus 41%: NS). However, for selection of valvular heart disease (n = 7), BNP testing had higher sensitivity than ECG testing (100% versus 14%; P < 0.01) with comparable specificity (43% versus 40%: NS). Several types of structural heart disease, in particular valvular heart disease, could be identified exclusively by BNP testing, suggesting that BNP measurement can make a significant contribution to screening for CHF precursors when used in combination with ECG in elderly populations.

Analytical evaluation of the Dade Behring Dimension RxL automated N-Terminal proBNP (NT-proBNP) method and comparison with the Roche Elecsys 2010

Methods to quantify B-type natriuretic peptide (BNP) and N-terminal-propeptide (NT-proBNP) in plasma or serum samples are well established. We assessed the analytical performance of the Dimension RxL NT-proBNP method (Dade-Behring). Evaluation of different sample types was carried out. Controls and heparin plasma pools were used to determine the detection limit, precision, and linearity. Sample stability and the effect of interfering substances on the NT-proBNP concentrations were evaluated. Agreement between Dimension RxL and Elecsys 2010 (Roche Diagnostics) NT-proBNP methods was assessed. The influence of age and sex on NT-proBNP concentrations was evaluated in healthy subjects. Heparin plasma should be the matrix of choice. The detection limit was 2.0ng/L. The total imprecision was 2.6–3.6% for concentrations from 231 to 9471ng/L; mean NT-proBNP concentrations of 21 and 15ng/L were associated with coefficients of variation of 9.9% and 14.7%, respectively. The method was linear up to 32,650ng/L. There was no effect of temperature, freeze-thaw cycles and interfering substances. A bias was detected when Dimension RxL and Elecsys 2010 NT-proBNP methods were compared. Age and sex were significantly and independently related to NT-proBNP concentrations. The Dimension RxL NT-proBNP method, like the Elecsys 2010, is suitable for routine use in the diagnosis of 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.

What factors are associated with high plasma B-type natriuretic peptide levels in a general Japanese population?

There are few community-based epidemiologic studies that have dealt with risk factors for heart failure in non-Western populations. It has been reported that the measurement of plasma B-type natriuretic peptide (BNP) is useful for detecting patients with asymptomatic heart failure. To clarify the determinants of high plasma BNP level, the association of BNP with cardiovascular risk factors in community dwelling residents was examined. The plasma BNP levels were measured in 686 residents aged 35-69 years who received annual health check-up. The relationship of BNP to blood pressure, blood haemoglobin, serum cholesterol (total and high-density lipoprotein cholesterol), plasma glucose, electrocardiographic (ECG) findings, urinary salt excretion, and lifestyle factors (smoking and alcohol consumption) were cross-sectionally analysed. The plasma BNP geometric mean was 13.7 pg/ml. Both linear and logistic regression analyses indicated that the plasma BNP levels were positively associated with age, urinary salt excretion, higher blood pressure, high R-wave voltage in the 12-lead ECG (Minnesota Code 3-1 or 3-3), and female gender. Plasma BNP levels were inversely associated with blood haemoglobin levels. Gender-specific analysis showed similar results. However, plasma BNP did not correlate with other cardiovascular risk factors such as serum lipids.

Biochemical indicators of cardiac and renal function in a healthy elderly population

OBJECTIVES

To examine the distributions of NT-proBNP and cystatin C and their relation to age, gender, and other physiological factors in an apparently healthy elderly population.

METHOD

NT-proBNP and cystatin C were analyzed in 407 and 408 healthy individuals, median age: 65 (range 40-76).

RESULTS

Increasing age, female gender and CRP were independently associated to higher NT-proBNP levels. Age, body mass index, and CRP level were independently associated to the cystatin C level. In women and men, < or =65 years, the 97.5th percentile value for NT-proBNP was 268 ng/l and 184 ng/l, in those older, 391 ng/l and 269 ng/l. For those < or =65 years the 97.5th percentile value for cystatin C was 1.12 mg/l, and for those older 1.21 mg/l.

CONCLUSION

In a healthy elderly population, NT-proBNP is influenced by age and gender, whereas cystatin C is influenced by age but not by gender. Both markers seem to be associated to the CRP level.

The effect of diabetes on B-type natriuretic peptide concentrations in patients with acute dyspnea: an analysis from the Breathing Not Properly Multinational Study

OBJECTIVE

Diabetes has been implicated in reduced myocardial compliance and changes in the intercellular matrix of the myocardium. We determined the effect of diabetes on B-type natriuretic peptide (BNP) concentrations in patients presenting to the emergency department with dyspnea.

RESEARCH DESIGN AND METHODS

The Breathing Not Properly Multinational Study was a prospective evaluation of 1,586 patients. A subset of 922 patients was obtained and subdivided into the following groups: group 1 (n = 324), neither diabetes nor heart failure; group 2 (n = 107), diabetes and no heart failure; group 3 (n = 247), no diabetes and heart failure; group 4 (n = 183), both diabetes and heart failure; group 5 (n = 41), heart failure history with no diabetes; and group 6 (n = 20), heart failure history with diabetes. Patients from groups 1, 3, and 5 were matched to groups 2, 4, and 6, respectively, to have the same mean age, sex distribution, BMI, renal function, and New York Heart Association (NYHA) classification (for heart failure).

RESULTS

There was no significant difference in median BNP levels between diabetes and no diabetes among no heart failure patients (32.4 vs.32.9 pg/ml), heart failure patients (587 vs. 494 pg/ml), and those with a heart failure history (180 vs. 120 pg/ml). Receiver-operating characteristic curve analysis of the area under the curve for BNP was not different in diabetic versus nondiabetic patients (0.888 vs. 0.878, respectively). However, in a multivariate model, diabetes was an independent predictor of a final diagnosis of heart failure (odds ratio 1.51, 95% CI 1.03-2.02; P < 0.05).

CONCLUSIONS

History of diabetes does not impact BNP levels measured in patients with acute dyspnea in the emergency department. Despite the impact of diabetes on the cardiovascular system, diabetes does not appear to confound BNP levels in the emergency department diagnosis of heart failure.

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.

N-terminal pro-brain natriuretic peptide predicts cardiovascular events in patients with hypertension and left ventricular hypertrophy

BACKGROUND

N-terminal pro-brain natriuretic peptide (Nt-proBNP) and N-terminal pro-atrial natriuretic peptide (Nt-proANP) are strong cardiovascular risk markers in patients with chronic heart failure, as well as in the general population. We investigated whether high Nt-proBNP or Nt-proANP could also predict the composite endpoint (CEP) of cardiovascular death, non-fatal stroke or non-fatal myocardial infarction in patients with hypertension and left ventricular (LV) hypertrophy.

METHODS

After 2 weeks of placebo treatment, clinical, laboratory and echocardiographic variables were assessed in 183 hypertensive participants in the LIFE echo substudy with electrocardiographic LV hypertrophy. Nt-proBNP and Nt-proANP were measured by immunoassay at baseline. The patients were followed for 60 +/- 5 months.

RESULTS

Using Cox regression analysis, the 25 CEP were predicted by ln(Nt-proBNP) (hazard ratio 1.61 per 2.73-fold increase, P < 0.01) as well as ln(Nt-proANP) (hazard ratio 2.93, P < 0.05). Nt-proBNP above the median value of 21.8 pmol/ml was associated with higher incidence of CEP (19.6 versus 7.7%, P < 0.05). Nt-proBNP above the median value was associated with higher incidence of CEP in the 123 patients without history of diabetes or cardiovascular disease (14.8 versus 4.3%, P < 0.05), but the association was insignificant in the 60 patients with a history of diabetes or cardiovascular disease (26.3 versus 18.2%, NS). Nt-proANP showed the same tendency.

CONCLUSION

Nt-proBNP, more than Nt-proANP, strongly predicts cardiovascular events in patients with hypertension and LV hypertrophy, especially in patients without diabetes or clinically overt cardiovascular disease.

A Pilot Study of Dendroaspis Natriuretic Peptide in Aneurysmal Subarachnoid Hemorrhage

OBJECTIVE:

Hypovolemia after aneurysmal subarachnoid hemorrhage (SAH) may be mediated by natriuretic peptides and can further impair cerebral perfusion in dysau-toregulated and vasospastic arterial territories. Dendroaspis natriuretic peptide (DNP), derived from the venom of Dendroaspis augusticeps, the Green Mamba snake, has recently been discovered in human plasma and atrial myocardium. There is no information regarding the presence or putative role of this peptide in patients with aneurysmal SAH.

METHODS:

A sensitive and specific DNP radioimmunoassay was performed on venous blood samples obtained on post-SAH Days 1, 3, and 7 from 10 consecutive SAH patients (cases) and randomly from 9 healthy volunteers (controls). Clinical and laboratory data, including daily serum sodium concentration and fluid balance, were collected prospectively up to 7 days after the ictus.

RESULTS:

Increase in plasma DNP levels occurred in five (63%) of eight patients who had DNP levels measured on Days 1 and 3 (mean increase, 29%). An increase in DNP level was significantly associated with development of a negative fluid balance (P = 0.003) and hyponatremia (P = 0.008). Three (75%) of the four patients who developed cerebral vasospasm during this study experienced an increase in DNP levels from Days 1 to 3.

CONCLUSION:

The present study is the first to find a significant association between elevated levels of DNP, a new member of the natriuretic peptide family, and the development of diuresis and natriuresis in patients with aneurysmal SAH. Our findings warrant further investigation by means of a large-scale, prospective, case-control study.

Plasma Brain Natriuretic Peptide to Detect Preclinical Ventricular Systolic or Diastolic Dysfunction

BACKGROUND

Preclinical systolic or diastolic dysfunction is associated with increased morbidity and mortality. We postulated that plasma brain natriuretic peptide (BNP) might serve as a biomarker for preclinical ventricular dysfunction (PCVD) but that the discriminatory values for BNP may vary with age and sex.

METHODS AND RESULTS

We measured BNP, systolic and diastolic ventricular function, and clinical parameters in 2042 randomly selected residents of Olmsted County, Minn, aged 45 years or older. For preclinical systolic dysfunction, the areas under the receiver operating characteristics curve were higher for those with more severe (0.82 to 0.92) than any (0.51 to 0.74) systolic dysfunction and were similar in men and women and in younger and older persons. For preclinical diastolic dysfunction, the areas under the receiver operating characteristics curve were higher for those with moderate-to-severe (0.74 to 0.79) than any (0.52 to 0.68) diastolic dysfunction and were similar regardless of age or sex. Optimal discriminatory values of BNP varied with age and sex. Considering the prevalence of preclinical systolic or diastolic dysfunction and the predictive characteristics observed, using BNP to screen for PCVD would necessitate echo in 10% to 40% of those screened, with most confirmatory echocardiograms being negative, and would miss 10% to 60% of those affected.

CONCLUSIONS

BNP is a suboptimal screening test for PCVD in the population.