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

The effect of hemodialysis on N-terminal pro-brain natriuretic peptide: A systematic review and meta-analysis

BACKGROUND

N-terminal pro-brain natriuretic peptide (NT-pro BNP) increases in patients with heart failure and renal failure. Hemodialysis is a useful treatment to these patients. The aim of this study was to conduct a systematic and meta-analysis to evaluate the influence of hemodialysis on NT-pro BNP concentration.

METHODS

Relevant studies were identified by searching in PubMed, Medline, Embase, OVID, Web of Science, China Biology Medicine (CBM) and Google Scholar. Standard errors of mean difference along with its 95% CI were calculated to assess the association of hemodialysis and NT-pro BNP concentration. Heterogeneity, subgroup analysis, sensitivity analysis and publication bias were explored.

RESULTS

Individual patient data was obtained from 270 participants in seven articles suffered from chronic renal failure with regular hemodialysis, which was standard normal distribution. A fixed effects model suggested a pooled mean difference of 79.265 (95% CI: -331.172-489.702) without heterogeneity (Q = 0.70 df = 6 p = 0.994 I² = 0.0%). The adults group estimated a MD of 209.958 (95% CI: -3080.76-3500.67; p = 0.900) with no heterogeneity (Q = 0.70 df = 4 p = 0.983 I² = 0.0%). In the four articles whose data were not standard normal distribution, hemodiafiltration protocols were similar; three articles reported increasing and one decreasing in NT-proBNP concentration.

CONCLUSIONS

Finding of this systematic review and meta-analysis demonstrated that NT-pro BNP may not been influenced by hemodialysis, and it could not been used to determine if heart failure is improving in patients with renal failure who are treated with hemodialysis.

Cardiac biomarkers in dialysis

Cardiovascular disease is the major cause of death, accounting for approximately 40 percent of all-cause mortality in patients receiving either hemodialysis or peritoneal dialysis. Cardiovascular risk stratification is an important aspect of managing dialysis patients as it enables early identification of high-risk patients, so therapeutic interventions can be optimized to lower cardiovascular morbidity and mortality. Biomarkers can detect early stages of cardiac injury so timely intervention can be provided. The B-type natriuretic peptides (Brain Natriuretic peptide [BNP] and N-terminal pro-B-type natriuretic peptide [NT-proBNP]) and troponins have been shown to predict mortality in dialysis patients. Suppression of tumorigenicity 2 (ST2) and galectin-3 are new emerging biomarkers in the field of heart failure in both the general and dialysis populations. This article aims to discuss the current evidence regarding cardiac biomarker use to diagnose myocardial injury and monitor the risk of major adverse cardiovascular events in patients undergoing dialysis.

Multiple biomarkers including cardiac troponins T and I measured by high-sensitivity assays, as predictors of long-term mortality in patients with chronic renal failure who underwent dialysis

There is a high cardiac mortality in patients on long-term renal dialysis. No studies have reported long-term outcomes relating to both high-sensitivity cardiac troponin T (hs-cTnT) and high-sensitivity cardiac troponin I (hs-cTnI) in these patients. Patients who underwent long-term dialysis at the Canberra Hospital had blood samples collected for both cardiac and other biomarkers. Samples were stored at -80°C until analysis. Mortality data were collected at 5 years, and univariate and multivariate analyses were performed to identify which biomarkers were predictive of mortality at 5 years. After multivariate analysis, albumin, C-reactive protein (CRP), and hs-cTnT remained independently predictive of all-cause mortality, with hs-cTnT having the highest hazard ratio. If hs-cTnT was excluded from the analysis, then hs-cTnI was independently predictive of mortality. For hs-cTnT, for both genders, the ninety-ninth percentile, derived from a population with subjects with subclinical disease excluded, served as an excellent partition between survivors and nonsurvivors. Receiver-operating characteristic curve analysis for hs-cTnT had area under the curve of 0.798 and for hs-cTnI of 0.774. Kaplan-Meier curves for the aggregation of albumin, CRP, and hs-cTnT showed a stronger predictive power with receiver-operating characteristic area under the curve of 0.805. The addition of echocardiographic data in an analysis of all patients who had an echocardiogram for clinical reasons (n = 105) did not alter the final observations in this subgroup. In conclusion, hs-cTnT retains a superior predictive power in a dialysis-dependent population for identifying those at risk for death and when aggregated with albumin and CRP also has substantial additive value for identifying mortality risk in a renal-dialysis population.

Cardiovascular disease in chronic kidney disease: untying the Gordian knot

Chronic kidney disease (CKD) affects around 10-13% of the general population, with only a small proportion in end stage renal disease (ESRD), either on dialysis or awaiting renal transplantation. It is well documented that CKD patients have an extremely high risk of developing cardiovascular disease (CVD) compared with the general population, so much so that in the early stages of CKD patients are more likely to develop CVD than they are to progress to ESRD. Various pathophysiological pathways and explanations have been advanced and suggested to account for this, including endothelial dysfunction, dyslipidaemia, inflammation, left ventricular hypertrophy and cardiac autonomic dysfunction. In this review, we try to understand and further explore the link between CKD and CVD, as well as offering interventional advice where available, while exposing the current lack of RCT-based research and trial evidence in this area. We also suggest pragmatic Interim measures we could take while we wait for definitive RCTs.

Changes in N-terminal pro-brain natriuretic peptide correlate with fluid volume changes assessed by bioimpedance in peritoneal dialysis patients

BACKGROUND/AIMS

Both brain natriuretic peptide (BNP) and volume overload are reported to be powerful predictors of survival for peritoneal dialysis patients. The usefulness of single BNP determinations in helping determine volume status in peritoneal dialysis patients remains controversial, so we reviewed serial BNP and multifrequency bioimpedance measurements to determine whether changes in BNP reflected changes in volume status.

METHODS

Prospective measurements of fluid volume by multifrequency bioimpedance and serum N-terminal pro-BNP (NTproBNP) were conducted in stable adult peritoneal dialysis outpatients attending for routine assessments of peritoneal dialysis adequacy and transport status.

RESULTS

A total of 189 serial measurements were made in 92 patients, and NTproBNP increased from a median of 162.5 pmol/l (interquartile range 82-385.4) to 195 pmol/l (interquartile range 101.9-348.6; p < 0.05). Changes in NTproBNP correlated with changes in extracellular water (ECW), total body water (TBW) and ECW/TBW (r = 0.38, 0.31 and 0.45, respectively; all p < 0.0001). Patients were divided into quartiles depending upon NTproBNP changes; those with the greatest fall in NTproBNP had significant falls in ECW (p < 0.001), TBW (p = 0.001) and ECW/TBW (p < 0.001) compared to the quartile with the greatest increase in NTproBNP, who also had an increase in systolic blood pressure from 133.5 ± 22.7 to 142.7 ± 28.8 mm Hg (p = 0.0078), whereas it fell in the quartile with the greatest fall in NTproBNP (143.8 ± 24.6 vs. 136.5 ± 18.7 mm Hg).

CONCLUSIONS

Serial measurements of NTproBNP correlated with changes in volume assessments made by multifrequency bioimpedance in peritoneal dialysis outpatients. As multifrequency bioimpedance measures total ECW, rather than effective plasma volume, serial NTproBNP determinations may prove an adjunct to the clinical assessment of volume status in peritoneal dialysis patients.

The prognostic value of estimated glomerular filtration rate, amino-terminal portion of the pro-hormone B-type natriuretic peptide and parameters of cardiopulmonary exercise testing in patients with chronic heart failure

The aim of this study was to evaluate the prognostic value of renal function in relation to amino-terminal portion of the pro-hormone B-type natriuretic peptide (NT-proBNP) and parameters of cardiopulmonary exercise testing in predicting mortality and morbidity in patients with moderate chronic heart failure (CHF). Sixty-one CHF patients were included in the study. Patients' characteristics were: age 64.3±11.6 years; New York Heart Association class I/II/III: 14/37/10; left ventricular ejection fraction: 0.30±0.13 (%); NT-proBNP: 252.2±348.0 (ng/L); estimated creatinine clearance (e-CC): 73.6±31.4 (mL/min); estimated glomerular filtration rate (e-GFR): 66.1±24.6 (mL/min/1.73 m²); the highest O2 uptake during exercise (VO_2-peak): 1.24±0.12 mL/kg/min; VO₂/workload: 8.52±1.81 (mL/min/W)]. During follow up (59.5±4.0 months) there were 15 cardiac deaths and 16 patients were hospitalized due to progression of heart failure. NT-proBNP and VO₂/workload were independently associated with cardiac death (P=0.007 and P=0.006, respectively). Hospitalization for progressive CHF was only associated with NT-proBNP (P=0.002). The combined cardiac events (cardiac death and hospitalization) were associated with NT-proBNP and VO₂/ workload (P=0.007 and P=0.005, respectively). The addition of estimates of renal function (neither serum creatinine nor e-GFR) did not improve the prognostic value for any of the models.In conclusion, in patients with moderate CHF, increased NT-proBNP and reduced VO₂/ work-load identify those with increased mortality and morbidity, irrespective of estimates of renal function.

Relation of N-terminal pro B-type natriuretic peptide levels after symptom-limited exercise to baseline and ischemia levels

Circulating levels of B-type natriuretic peptide (BNP) and the amino-terminal portion of the prohormone (NT-proBNP) have been reported to increase immediately after myocardial ischemia. The association between extent of exercise-induced myocardial ischemia measured using myocardial perfusion scintigraphy and the magnitude and time course of changes in NT-proBNP was studied. One hundred one patients underwent symptom-limited exercise myocardial perfusion scintigraphy. Myocardial ischemia was assessed semiquantitatively. Serum samples were obtained before the start of exercise (baseline), at maximal exercise, and every hour up to 6 hours after maximal exercise. Myocardial ischemia was present in 37 patients (37%). NT-proBNP rapidly increased during exercise (to 113%, interquartile range 104 to 144, and 118%, interquartile range 106 to 142, of baseline, respectively), with a second peak at 4 (141%, interquartile range 119 to 169) and 5 hours (136%, interquartile range 93 to 188), respectively. Absolute changes between NT-proBNP at baseline and at maximum exercise in patients with versus without ischemia were similar (median, 30 pg/ml, interquartile range 7 to 45 vs 15, interquartile range 4 to 46, respectively, p = 0.230), but absolute change between baseline and the secondary peak was higher in patients with ischemia than in patients without ischemia (median 64 pg/ml, interquartile range 32 to 172 vs 34, interquartile range 19 to 85, respectively, p = 0.024). In multivariate linear stepwise regression analysis of determinants of changes in NT-proBNP after exercise, baseline NT-proBNP was the only independent determinant of absolute changes at maximum exercise, whereas the presence of ischemia was not predictive. Baseline NT-proBNP, cystatin C, and end-systolic volume were independent determinants of the absolute increase to secondary peak levels. In conclusion, myocardial ischemia per se did not lead to additional increases in NT-proBNP within 6 hours after exercise.

Nt-proBNP in haemodialysis patients: a preliminary study

OBJECTIVE

N-terminal pro-brain natriuretic peptide (Nt-proBNP) is a marker of left ventricular function. Although many factors can increase left ventricular dysfunction in haemodialysis patients, the role of Nt-proBNP is uncertain.

MATERIAL AND METHODS

Serum concentrations of Nt-proBNP and troponin T were measured by electrochemiluminescence and C-reactive protein by immunoturbidimetry in 52 dialysis patients followed-up for 36 months.

RESULTS

Nt-proBNP correlated (p<0.05) with time on haemodialysis (rho=0.345), left ventricular mass index (r=0.596), troponin T level (r=0.605) and age (r=0.296). Patients with a history of heart disease showed higher levels of Nt-proBNP (median; minimum-maximum ngl/L) (15,571; 1,553-209,451) than those without (4,535; 751-115,078) (p<0.01). Sensitivity and specificity of Nt-proBNP in the detection of left ventricular dysfunction (ventricular ejection fraction < 45%) were 1.0 and 0.782, respectively. In the univariate analysis, patients with Nt-proBNP levels > or = 33,314 ng/L, CRP > or = 5 mg/L or troponin T > or = 0.1 microg/L had poorer probabilities of 1-year, 2-year and 3-year survival than patients with lower levels. Unfavourable prognostic factors in the multivariate analysis were CRP > 5 mg/L and Tn T > 0.1 microg/L.

CONCLUSIONS

Nt-proBNP showed good diagnostic performance for detecting left ventricular dysfunction and was an important predictor of mortality in haemodialysis patients in the univariate analysis. In the multivariate analysis, Nt-proBNP lost its prognostic value, whereas for CRP and Tn T it was maintained.

N-terminal pro brain natriuretic peptide predicts mortality in patients with end-stage renal disease in hemodialysis

Concentrations of N-terminal pro brain natriuretic peptide (NT-proBNP) increase in patients with heart failure and other cardiovascular (CV) diseases and are strong prognostic markers. In patients with end-stage renal disease (ESRD) in hemodialysis (HD), levels of NT-proBNP are almost always raised. In ESRD patients undergoing HD, we aimed at (i) identifying the factors that affect levels of NT-proBNP, (ii) determining the effect of HD on NT-proBNP, and (iii) determining the prognostic impact of NT-proBNP. A total of 109 patients underwent physical examination, electrocardiogram, and echocardiography. Serum NT-proBNP was measured before and after HD (Elecsys 2010). NT-proBNP levels were markedly elevated (pre-HD 4079 pg/ml, post-HD 2759 pg/ml, P<0.001). There was a strong inverse correlation between NT-proBNP and left ventricular ejection fraction (LVEF) (P=0.043), 24-h urine production (P=0.006), and K(t)/V (efficacy of dialysis) (P=0.016) and a positive correlation with left ventricular hypertrophy (LVH) (P=0.014). Patients with higher concentrations, both pre- and post-HD had an increased mortality rate compared to those with lower concentrations (P=0.007, P=0.002). We found age (P=0.009) and NT-proBNP (pre-HD P=0.007, post-HD P=0.001) predictive of death. Our findings demonstrate that CV disease in terms of LVH and reduced LVEF in addition to 24-h urine production and K(t)/V determine NT-proBNP levels. Post-HD levels of NT-proBNP were lower than pre-HD levels; both predictive of mortality.

Changes in plasma B-type natriuretic peptide after allograft renal transplantation

OBJECTIVE

To investigate the dynamic changes in plasma B-type natriuretic peptide (BNP) after allograft renal transplantation.

METHODS

Plasma BNP was measured in 17 patients before and after unilateral allograft renal transplantation (study group) and in 17 age- and sex-matched healthy individuals (control group).

RESULTS

Average BNP level in the study group was significantly higher than in the control group before renal transplantation (P < 0.001). After transplantation, blood pressure was reduced and left ventricular ejection fraction was increased (P < 0.01). There was also a substantial reduction in plasma BNP and blood creatinine following the surgery (P < 0.001). Graft dysfunction accompanied by significant rebound in plasma BNP levels was detected in four patients within 2 weeks of the surgery.

CONCLUSION

Plasma BNP levels are elevated in patients with chronic renal failure. Allograft renal transplantation significantly reduces BNP. Sudden increases in plasma BNP after the transplantation are associated with allograft dysfunction. Together with other biomarkers, plasma BNP may be used to predict the changes in renal function after transplantation.

An evaluation of blood volume changes during ultrafiltration pulses and natriuretic peptides in the assessment of dry weight in hemodialysis patients

Changes in blood volume (BV) during dialysis as well as plasma levels of brain natriuretic peptide (BNP) and N-terminal (NT) pro-BNP levels are possible tools to assess dry weight in hemodialysis (HD) patients. The aim of the study was to compare these parameters with other non-invasive techniques used to assess dry weight in HD patients, and to study their relation with intradialytic hypotension (IDH) and the presence of cardiovascular disease BV changes during HD, both during regular dialysis and during an ultrafiltration pulse, plasma levels of NT pro-BNP and BNP, and vena cava diameter index (VCDI) were assessed in a cohort of 66 HD patients, which was subdivided according to tertiles of total body water (TBW) corrected for body weight, assessed by bioimpedance analysis. Parameters were also related to the presence of IDH and history of cardiovascular disease. The decline in BV during regular dialysis and during an ultrafiltration pulse, as well as VCDI and BNP were significantly different between the tertiles of normalized TBW, but refill after the ultrafiltration pulse and NT pro-BNP were not. Only VCDI and the decline in BV during regular dialysis were significantly different between patients with or without IDH. Vena cava diameter index, BNP, and NT pro-BNP were significantly higher in patients with cardiovascular disease. Using bioimpedance as the reference method, changes in BV, either during regular dialysis or during an ultrafiltration pulse, as well as VCDI and BNP are all indicative of hydration state in dialysis patients, but refill after an ultrafiltration pulse is not. Only VCDI and BV changes were related to IDH. The presence of cardiovascular disease appears to influence both VCDI as well as BNP.

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.

Abnormal rhythmic oscillations of atrial natriuretic peptide and brain natriuretic peptide in chronic renal failure

Secretion of ANP (atrial natriuretic peptide) and BNP (brain natriuretic peptide) is pulsatile in healthy humans. However, the patterns of secretion of ANP and BNP have not been studied in chronic renal failure. The aim of the present study was to test the hypotheses that ANP and BNP are secreted in pulses in dialysis patients, and that pulsatile secretion is regulated by prostaglandins. Blood samples were drawn every 2 min through an intravenously inserted plastic needle over a period of 1-2 h in 13 dialysis patients and 13 healthy control subjects (Study 1), and in 15 healthy control subjects, who participated in a randomized placebo-controlled cross-over study after treatment with indomethacin and placebo (Study 2). Plasma concentrations of ANP and BNP were determined by RIAs, and the results were analysed for pulsatile behaviour by Fourier transformation. The results from Study 1 showed that the secretion of ANP and BNP was pulsatile in nine patients with chronic renal failure. The maximum amplitude was significantly higher in chronic renal failure compared with control subjects for both ANP and BNP (ANP, 4.3 compared with 0.7 pmol/l; BNP, 2.0 compared with 0.3 pmol/l; values are medians) and correlated positively with the mean plasma level of ANP (rho=0.900, P=0.001; n=9) and BNP (rho=0.983, P=0.000; n=9). The frequency was the same for patients and controls. The results from Study 2 demonstrated pulsatile secretion in all subjects, but both the amplitude and frequency were unaffected by indomethacin. The maximum amplitude correlated positively with the mean plasma level of ANP and BNP during both placebo and indomethacin treatment. It can be concluded that the secretion of ANP and BNP is pulsatile with abnormally high amplitude in chronic renal failure, that prostaglandins apparently are not involved in the secretion of these peptides in healthy subjects and that the high secretion rate in chronic renal failure results in higher ANP and BNP in plasma.

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.

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.

Influence of renal function on N-terminal pro-brain natriuretic peptide (NT-proBNP) in patients admitted for dyspnoea in the Emergency Department: Comparison with brain natriuretic peptide (BNP)

BACKGROUND

Renal dysfunction influences the optimum brain natriuretic peptide (BNP) threshold for a diagnosis of cardiac-related dyspnoea, but this has not been demonstrated for N-terminal pro-brain natriuretic peptide (NT-proBNP). We studied the influence of renal function on NT proBNP and BNP concentrations in dyspnoeic patients admitted by night to the Emergency Department (ED).

METHODS

NT-proBNP, BNP, and creatinine levels were measured in blood samples collected routinely from 381 patients; estimated glomerular filtration rate (eGFR) was calculated.

RESULTS

Cardiac-related dyspnoea was found in 115 patients (30.2%). NT-proBNP and BNP values were elevated in patients with cardiac-related dyspnoea (6823+/-6569 vs. 2716+/-4838 pg/ml, and 642+/-329 vs. 243+/-267 pg/ml, p<0.0001, respectively). Log-transformed NT-proBNP and BNP values were correlated to eGFR values. Mean NT-proBNP and BNP values stratified by ED diagnosis increased in line with eGFR categories, but in each category both peptide concentrations remained elevated in cardiac-related dyspnoea when compared with non-cardiac-related dyspnoea (p<0.05). NT-proBNP (and BNP) cut-off points rose as a function of eGFR categories: from 1360 (and 290) pg/ml in patients with eGFR 60-89 ml/min/1.73 m2, to 6550 (and 515) pg/ml in patients with eGFR 15-29 ml/min/1.73 m2.

CONCLUSION

Renal function influences the optimal cut-off points of NT-proBNP and BNP for the diagnosis of cardiac-related dyspnoea.

B-Type Natriuretic Peptide (BNP) and Amino-Terminal proBNP in Patients With CKD: Relationship to Renal Function and Left Ventricular Hypertrophy

BACKGROUND

Most patients with chronic kidney disease (CKD) develop cardiovascular complications. Natriuretic peptides are novel markers that can be used to identify and monitor heart failure, but the effect of renal disease on these markers is not fully understood. The aim of the present study is to explore the relationship among circulating B-type natriuretic peptide (BNP) and N-terminal proBNP (NT-proBNP) concentrations and clinical variables in a cohort of patients with CKD.

METHODS

Plasma BNP and NT-proBNP concentrations and left ventricular (LV) mass index were measured in 213 predialysis patients with CKD.

RESULTS

Plasma BNP and NT-proBNP concentrations increased with declining estimated glomerular filtration rate (GFR; P < 0.0001). Estimated GFR had an independent effect on plasma BNP (P = 0.0028) and, to a greater extent, plasma NT-proBNP (P < 0.0001) concentrations: mean BNP concentration increased by 20.6% per 10-mL/min/1.73 m2 (0.17-mL/s) reduction in estimated GFR compared with 37.7% for NT-proBNP. NT-proBNP/BNP ratio increased with CKD stage (P < 0.0001). Median plasma BNP and NT-proBNP concentrations were greater in patients with LV hypertrophy (P < 0.0001), and LV mass index had an independent effect on both BNP (P = 0.0223) and NT-proBNP (P < 0.0017).

CONCLUSION

Estimated GFR and LV mass index have independent effects on both plasma BNP and NT-proBNP concentrations in patients with CKD. NT-proBNP appears to be affected more by declining kidney function, in keeping with the hypothesis that its clearance is predominantly renal. Our data have significant implications for application of these peptides as cardiac biomarkers in patients with CKD.

Effect of Compensated Renal Dysfunction on Approved Heart Failure Markers

Brain natriuretic peptide (BNP) and N-terminal pro-BNP (NT-proBNP) are markers of heart failure. Although renal dysfunction may increase plasma concentrations, the magnitude of this effect has not been assessed in a head-to-head comparison between the clinically approved tests. We assessed the effect of compensated renal dysfunction on BNP (Triage BNP; Biosite) and NT-proBNP (elecsys proBNP; Roche) in 469 randomly selected stable outpatients after myocardial infarction (MI; Monitoring Trends and Determinants in Cardiovascular Diseases [MONICA] register Augsburg) who were characterized with respect to renal function (glomerular filtration rate [GFR]; Cockroft method) and left ventricular (LV) ejection fraction (EF) and mass (2D echocardiography). BNP and NT-proBNP were elevated in MI patients with LV dysfunction (LVD; EF <35%) compared with MI patients with preserved EF (>45%; BNP 139±27 pg/mL versus 75±6; NT-proBNP 816±237 pg/mL versus 243±20; both P <0.03). Among all MI patients, the prevalence of renal dysfunction (GFR <85 mL/min) was 24%. BNP and NT-proBNP were significantly elevated in MI patients with renal dysfunction (BNP 132±17 pg/mL versus 68±4 without renal dysfunction; NT-proBNP 535±80 pg/mL versus 232±19; both P <0.05), and both markers were correlated with GFR in univariate and multivariate analyses (all P <0.01). When binary cut-off values were stratified according to the absence or presence of renal dysfunction (BNP 75 pg/mL and 125 pg/mL, respectively; NT-proBNP 100 pg/mL and 350pg/mL, respectively), the predictive power of both markers for the detection of LVD increased substantially. BNP and NT-proBNP are almost similarly influenced by mild-to-moderate renal dysfunction. Renal dysfunction is a potential cause of elevated marker concentrations in the absence of LVD, and cut-off concentrations should be stratified according to renal function.

B-type natriuretic peptide and the prediction of outcome in patients admitted to intensive care

B-type natriuretic peptide is known to predict outcome in congestive cardiac failure and myocardial infarction. We aimed to determine whether measurement of B-type natriuretic peptide would predict hospital mortality in patients admitted to an intensive care unit. We conducted a prospective observational cohort study in 78 consecutive patients. Demographics, clinical details and clinical outcomes were recorded. Admission and 24 h B-type natriuretic peptide and cardiac troponin I levels were measured. B-type natriuretic peptide and cardiac troponin I levels taken on intensive care admission and 24 h after admission did not accurately predict hospital mortality for all patients, including patients with severe sepsis or septic shock (all p > 0.05). B-type natriuretic peptide levels were higher in patients with severe sepsis and septic shock (p = 0.02), in patients > or = 65 years (p = 0.04) and in patients with raised creatinine > or = 110 micromol.l(-1) (p = 0.02). We concluded that B-type natriuretic peptide, measured soon after admission to intensive care, does not usefully predict outcome after intensive care.

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.

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.

The natriuretic peptides and their role in disorders of right heart dysfunction and pulmonary hypertension

Atrial natriuretic peptide (ANP) and B-type natriuretic peptide (BNP) are increased in conditions with cardiac ventricular volume and pressure overload. The general physiological and potential therapeutic roles of natriuretic peptides in respiratory disease, right ventricular (RV) dysfunction, and pulmonary arterial hypertension (PAH) are reviewed. BNP levels can be used to differentiate between dyspneic patients with a pure respiratory defect and those with RV dysfunction. BNP levels also correlate with mean pulmonary arterial pressure (mPAP) and pulmonary vascular resistance (PVR) in patients with PAH (atrial septal defect, chronic thromboembolic disease, and scleroderma). BNP is a predictor of mortality in patients with primary pulmonary hypertension (PPH). These are important clinical implications in that a noninvasive blood test may be used to identify high-risk patients for more invasive procedures such as cardiac catheterization. BNP or NT-proBNP measurements may also be used to guide therapy (e.g., pulmonary vasorelaxants) in PAH since upregulation of the natriuretic peptide pathway has been shown to reduce cardiac hypertrophy and PAH. Additionally, there may be therapeutic potential via recombinant BNP or neutral endopeptidase inhibitors in RV dysfunction and PAH.

Multi-biomarker risk stratification of N-terminal pro-B-type natriuretic peptide, high-sensitivity C-reactive protein, and cardiac troponin T and I in end-stage renal disease for all-cause death

BACKGROUND

In patients with end-stage renal disease (ESRD), the ability of single and multiple biomarker monitoring to predict adverse outcomes has not been well established. This study determined the prognostic value of multiple biomarkers for all-cause death over 2 years in 399 ESRD patients.

METHODS

The risk of all-cause death was determined by use of multiple biomarkers based on concentrations for a reference population (normal) and cutoffs based on tertile distributions in the ESRD group. Biomarkers studied included N-terminal pro-B-type natriuretic peptide (NT-proBNP), high-sensitivity C-reactive protein (hsCRP; Dade Behring and Roche assays), and cardiac troponin T (cTnT; Roche) and I (cTnI; Dade Behring and Beckman Coulter assays). Relative risks of death were estimated and survival curves computed.

RESULTS

A total of 101 deaths occurred during 594 patient-years of follow-up. Increased NT-proBNP concentrations were not predictive of death on the basis of the normal cutoffs. However, tertile analysis of NT-proBNP was significantly predictive of death and had a ROC area under the curve equivalent to or better than any of the other biomarkers. Biomarkers independently predictive of survival were hsCRP (P <0.001, either assay), cTnT (P <0.05), and cTnI (Dade, P <0.05). Two-year mortality rates were 6% (n = 45) with normal hsCRP, cTnI, and cTnT concentrations; 19% (n = 173) with increased hsCRP or cTnT and normal cTnI; 44% (n = 160) with both hsCRP and cTnT increased and normal cTnI; 61% (n = 21) with increased cTnI (Dade) or 47% (n = 74) with increased cTnI (Beckman) regardless of hsCRP or cTnT concentrations. Defined by the normal cutoffs, increased concentrations of biomarkers were present in various proportions of the 399 patients with ESRD: NT-proBNP, 99%; hsCRP, 46% (both Roche and Dade assays); cTnT, 85%; cTnI, 19% (Beckman assay) and 5% (Dade assay).

CONCLUSIONS

Although mechanisms likely vary for causation, increased plasma hsCRP, cTnT, and cTnI above the cutoffs for our reference (normal) population were all independently predictive of subsequent death in ESRD patients. Tertile analysis for NT-proBNP also demonstrated prognostic value.

B-type natriuretic peptide: practical diagnostic use for evaluating ventricular dysfunction

Assessment of brain natriuretic peptide levels may provide important information that can be used in the evaluation of patients with dyspnea and follow-up of heart failure. Brain natriuretic peptide levels have been shown to be useful for evaluating patients in the emergency department and for evaluating patients complaining of dyspnea in the outpatient setting. Brain natriuretic peptide assessment also provides an adjunct to diagnosis of both systolic and diastolic dysfunction, has prognostic value for heart failure and in acute coronary syndromes, and may be a useful measure to guide therapy. Further work needs to be done to establish the best type of assay to use, to determine the optimal cutoff point for what is considered abnormal, and to determine how conditions other than ventricular dysfunction affect brain natriuretic peptide levels.

The confounding effects of age, gender, serum creatinine, and electrolyte concentrations on plasma B-type natriuretic peptide concentrations in critically ill patients

OBJECTIVE

To investigate the confounding effects of age, gender, serum creatinine, and electrolyte concentrations on plasma B-type natriuretic peptide (BNP) concentrations in critically ill patients.

DESIGN

A prospective cross-sectional study.

SETTING

A 20-bed general intensive care unit of a tertiary referral hospital.

PATIENTS

Patients were 121 patients admitted to the intensive care unit over a period of 9 wks.

INTERVENTIONS

Intravenous blood was collected for BNP measurements, and cardiac investigations including echocardiography were carried out for every patient on admission.

MEASUREMENTS AND MAIN RESULTS

The mean BNP concentration was 201 +/- 317 pg/mL (n = 121). Thirty-five patients (28.9%), identified to have cardiac abnormalities, exhibited higher BNP concentrations than those without cardiac abnormalities (518 +/- 394 vs. 60 +/- 98 pg/mL, p <.001). The females exhibited higher concentrations of BNP than males in the noncardiac abnormality group (96 +/- 132 pg/mL, n = 39 vs. 31 +/- 38 pg/mL, n = 47, p =.016). BNP correlated significantly with age (r2 =.19) and creatinine (r2 =.084). The latter correlation became insignificant when patients with cardiac abnormality were excluded. No correlation was found between serum Na+ and K+ concentrations with BNP. Multivariate analyses demonstrated that the presence of cardiac abnormalities accounted for nearly 50% of the BNP variation. Addition of age and gender improved R2 to 60%. The contribution of creatinine was found to be insignificant. There was no association between BNP concentrations and serum Na+ and K+ concentrations. Logistic analysis confirmed that BNP is the strongest predictor for cardiac abnormalities in the critically ill patients.

CONCLUSION

The current study demonstrated that plasma BNP concentrations increased with age and were higher in females than in males. Although the presence of cardiac disease was the most important determinant for BNP variations, age and gender also contributed significantly. The results suggest that age and gender need to be taken into account in the interpretation of BNP concentrations in critically ill patients.

Pathophysiological and clinical relevance of circulating levels of cardiac natriuretic hormones: are they merely markers of cardiac disease?

Several specific and sensitive markers for myocardial injury as well as diagnostic tests for the assessment and stratification of cardiovascular risk have been recently introduced in clinical laboratories. However, until a few years ago, there were no laboratory tests for diagnosis, stratification and follow-up of patients with heart failure. The assay for cardiac natriuretic hormones (CNH) fills this gap. Heart failure is not only the most frequent "final common pathway" in cardiovascular disease, but is also the most common primary hospital discharge diagnosis, as well as the most common cause of death in patients over 50 years of age in Western countries; therefore, CNH assay may be destined to assume a growing relevance in clinical cardiology. However, to consider CNH assay only as a general and functional indicator of cardiac structural disease, without recalling that atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) are powerful hormones, may lead to underestimation of the physiological role they play in healthy subjects as well as in patients with heart failure. Indeed, the circulating levels of CNH should be always interpreted taking into account not only hemodynamic factors and myocardial performance, but also their relationship with the counter-regulatory neuroendocrine system (including renin-angiotensin-aldosterone system, sympathetic system, endothelins, cytokines and vasopressin), as well as other hormones (such as sex steroid hormones, thyroid hormones and glucocorticoids).