[The value of natriuretic peptides NT-pro-BNP and BNP for the assessment of left-ventricular volume and function. A prospective study of 150 patients]

Influence of atrial fibrillation on cardiac brain natriuretic peptide release during haemodynamic stress in heart failure

BACKGROUND

The determinants of release of brain natriuretic peptide (BNP) in heart failure (HF) are incompletely understood, particularly, the effect of heart rhythm and haemodynamic stress.

AIMS

To investigate the effect of haemodynamic stress on cardiac BNP release in HF and differentiate this response for atrial fibrillation (AF) and sinus rhythm (SR).

METHODS

In 18 HF patients (ejection fraction<40%, 9 in AF and 9 in SR) haemodynamics and BNP levels were measured from arterial and coronary sinus samples at baseline, after 10 min of 20 degrees passive head up tilt (HUT) and after 10 min of isometric handgrip (IHG) exercise. From these data, we calculated a transcardiac BNP gradient and compared results between the AF and SR cohort.

RESULTS

During haemodynamic stress in both groups, there were no significance differences in left sided filling pressures. At baseline, there were no differences in BNP measurements between the SR and AF group. The transcardiac BNP gradient increased significantly in the SR (p=0.02) but not the AF cohort, after HUT. During IHG exercise, there was a significant decrease in cardiac BNP release in the AF cohort (p=0.03) but not the SR cohort.

CONCLUSION

These data imply in HF, cardiac rhythm influences cardiac BNP release in response to haemodynamic stress.

Accuracy of B-type natriuretic peptide levels in the diagnosis of left ventricular dysfunction and heart failure: a systematic review

OBJECTIVES

To evaluate the accuracy of B-type natriuretic peptide levels (BNP) in the diagnosis of heart failure and left ventricular dysfunction.

DATA SOURCES

Electronic search in Medline, Embase, Cochrane Library and Medion database, and hand search of reference lists.

REVIEW METHODS

We have included published studies on the accuracy of BNP which had both sufficient information to construct the 2x2 diagnostic cross table and an appropriate spectrum of patients.

RESULTS

Fifty five studies (16,730 patients) were analyzed. The main determinants of diagnostic accuracy were the reference standard analyzed (clinical heart failure versus left ventricular dysfunction), and the methodological quality of the study. BNP levels were highly accurate for the diagnosis of clinical heart failure (diagnostic OR=41; 95% CI 23-74). The negative likelihood ratios were homogeneous, and useful for excluding the existence of heart failure (pooled negative likelihood ratio=0.11; 95% CI 0.08-0.16). The studies focused on the identification of left ventricular dysfunction were heterogeneous, with indications of publication bias, and showed less overall diagnostic accuracy than studies focused on heart failure.

CONCLUSIONS

BNP levels are useful for ruling out heart failure. The accuracy of BNP for identifying patients with systolic dysfunction is more limited.

Evaluation of the analytical performance characteristics of the Bayer ACS:180® B-type natriuretic peptide (BNP) assay

BACKGROUND

B-type natriuretic peptide (BNP) is a cardiac hormone that regulates hemodynamic equilibrium and alleviates ventricular stress. In patients with chronic heart failure, BNP levels increase in proportion to the severity of clinical symptoms and degree of decreased left ventricular ejection fraction. BNP has clinical utility in the evaluation, management, and prognosis of patients with heart failure.

METHODS

We evaluated the analytical performance characteristics of the BNP immunochemiluminometric assay in the ACS:180 instrument at three hospital laboratory sites. The analytical performance characteristics evaluated included imprecision, sensitivity (minimum detectable concentration, MDC), analytical measurement range (AMR), dilution linearity/recovery, lot-to-lot reagent variation, high-dose hook effect, and comparison against ADVIA Centaur BNP results on patients' EDTA-plasma samples.

RESULTS

Total imprecision was <10% coefficient of variation at BNP concentrations of 43-1830 pg/ml; MDC was 6.9 pg/ml; AMR was 6.9-5000 pg/ml; overall recovery of BNP in samples diluted up to 1:10 was 98%; there was no lot-to-lot reagent variation in BNP results and no high-dose hook effect at BNP concentrations up to 100,000 pg/ml; and, ACS:180 results were highly correlated (r=0.996) with Centaur BNP results.

CONCLUSIONS

The ACS:180 BNP assay demonstrated excellent analytical performance characteristics and agreement with BNP results obtained using the Centaur instrument.

Natriuretic peptides and the prevalence of congestive heart failure in patients with pacemakers

AIM

The aim of the study was to investigate the diagnostic potential of natriuretic cardiac peptide measurement in the context of left ventricular dysfunction and comorbidities in a pacemaker population.

MATERIAL AND METHODS

Ninety-five consecutive patients with pacemakers were included in the study. All patients underwent echocardiography and were asked to complete the Minnesota Living with Heart Failure Questionnaire (MLHFQ). Brain natriuretic peptide (BNP), N-terminal proatrial natriuretic peptide (N-ANP) and atrial natriuretic peptide levels in plasma were measured.

RESULTS

Twenty-six percent of patients had reduced systolic left ventricular function; only 16 patients had a history of congestive heart failure. BNP was abnormally elevated in 64%, N-BNP in 72% and N-ANP in 96% of patients. Both BNP (r = 0.30; P < 0.01) and N-ANP (r = 0.39; P < 0.0005) correlated with MLHFQ. The strongest correlation was found between N-ANP and the ejection fraction (r = 0.6; P < 0.0001). Patients were stratified in a high-risk group and a low risk-group according to their N-ANP (N-ANP > 5000 fmol L(-1); n = 63 and N-ANP < 5000 fmol L(-1), n = 32) and BNP levels (BNP > 400 pg mL(-1); n = 17 and BNP < 400 pg mL(-1), n = 78). N-ANP was correlated with hypertension (P < 0.003) and atrial fibrillation (P < 0.03), and BNP with mitral insufficiency (P < 0.002).

CONCLUSIONS

Cardiac natriuretic peptides are markedly elevated in the majority of patients with pacemakers. The prognostic significance of BNP and N-ANP in left ventricular dysfunction warrants close follow-up schedules.

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 relationship between urotensin II plasma immunoreactivity and left ventricular filling pressures in coronary artery disease

The role of urotensin II (U-II)--a vasoactive, mitogenic, and inotropic, peptide--in the pathophysiology of heart failure is controversial. The present study explores the relationship between plasma U-II immunoreactivity (U-IIIR) and hemodynamics in patients with coronary artery disease (CAD). Thirty-six patients with CAD-3 undergoing coronary artery bypass grafting (CABG) with cardiopulmonary bypass (CPB) and 36 medical patients (MED group) with CAD-1 to CAD-3 during right heart catheterization were studied. Significant correlations were observed between pulmonary capillary wedge pressure (PCWP) and U-IIIR--determined by enzyme immunoassay (EIA)--before (rho = 0.83) and after (rho = 0.6) cardiopulmonary bypass in the CABG group. With the exception of the CPB period, CABG patients with increased PCWP before CPB had higher U-II(IR) concentrations throughout the procedure. Significant correlations were observed between U-IIIR, proANP, proBNP, and mean right ventricular pressure (RVPM) in MED patients. No correlation was detectable between U-IIIR and PCWP. However, MED patients with CAD-3 (n = 13) had higher levels of U-IIIR, NTproANPIR (RIA), NTproBNPIR (EIA) and higher cardiac filling pressures than patients with CAD-1 (n = 13). These findings support an association between plasma U-IIIR levels and diastolic myocardial dysfunction in ischemic heart failure. The discrepancies regarding left and right cardiac filling pressures and U-IIIR levels in CABG and MED patients require further evaluation.

Use of NT-proBNP in routine testing and comparison to BNP

OBJECTIVES

B-type natriuretic peptide (BNP) is a strong diagnostic predictor of left-ventricular (LV)-dysfunction. Recently, the aminoterminal portion of pro-BNP (NT-proBNP) has been introduced, which could be even more sensitive because of its longer half-life. The aim of this study was to evaluate the new marker NT-proBNP within a large, heterogeneous population of patients with suspected cardiovascular disease at risk of cardiovascular dysfunction and to compare it with the established diagnostic parameter BNP.

SUBJECTS AND METHODS

NT-proBNP and BNP were measured in 339 hospitalised patients undergoing diagnostic angiography (median age 66 years, 244 male vs. 95 female).

RESULTS

Median values of NT-proBNP increased with worsening LV-dysfunction and higher NYHA class. The area under the receiver operator characteristics curve (AUC) of NT-proBNP for detecting severe systolic dysfunction or for detecting any systolic LV-dysfunction was 0.83 and 0.77, respectively. The latter improved (AUC=0.81) when patients with clinically relevant heart disease like valvular dysfunction were included, independent of the haemodynamic values. Compared to BNP, NT-proBNP tended to be more accurate in identifying lesser degrees of LV-dysfunction.

CONCLUSIONS

Even after optimisation of target criteria, there was still a substantial overlap of NT-proBNP values between patients with and without relevant heart disease. Therefore, NT-proBNP is not suitable as a screening test for LV-dysfunction in the community. Nevertheless, because of its good negative predictive value, NT-proBNP could be an easy and effective tool to rule out severe systolic LV-dysfunction in high risk patients. No clinically significant advantage of BNP testing could be found.

The role and assessment of ventricular peptides in heart failure

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