Correlation of B-type natriuretic peptide level to 6-min walk test performance in patients with left ventricular systolic dysfunction

Functional capacity testing in patients with pulmonary hypertension (PH) using the one-minute sit-to-stand test (1-min STST)

BACKGROUND

The one-minute sit-to-stand-test (1-min STST) is a quick, space saving test to evaluate functional capacity. Exercise testing plays an important role in the long-term follow-up of pulmonary hypertension (PH) patients and is currently evaluated using the six-minute-walk-test (6MWT). The aim of the study was to assess the convergent validity of the 1-min STST in patients with PH and its association with markers of PH severity.

METHODS

We evaluated 106 PH patients with the 1-min-STST and 6MWT and measured cardiorespiratory parameters (heart rate, blood pressure, oxygen saturation) before and after test conduction. N-terminal pro brain-type natriuretic peptide (NT-proBNP), WHO functional class (WHO-FC) and mean pulmonary artery pressure (mPAP) were defined as markers of PH severity.

RESULTS

Strong correlation was found between performances of 1-min STST and 6MWT (r = .711, p < .001), indicating convergent validity. Both tests were inversely associated with NT-proBNP (STST: r = -.405, p < .001; 6MWT: r = -.358, p < .001), WHO-FC (STST: r = -.591, p < .001; 6MWT: r = -.643, p < .001) and mPAP (STST: r = -.280, p < .001; 6MWT: r = -.250, p < .001). Significant changes in cardiorespiratory parameters were observed in both tests (all p < 0.001). Further the post-exercise cardiorespiratory parameters correlated strongly between the 1-min STST and 6MWT (all r ≥ .651, all p < .001).

CONCLUSION

The 1-min STST demonstrated good convergent validity with the 6MWT and was associated with markers of PH severity. Furthermore, both exercise tests caused similar cardiorespiratory responses.

Plasma brain natriuretic peptide level in older outpatients with heart failure is associated with physical frailty, especially with the slowness domain

Objective

To determine the association between plasma brain natriuretic peptide (BNP) level in patients with heart failure (HF) and physical frailty as well as with each domain of physical frailty.

Methods

Two hundred and six outpatients of cardiovascular medicine aged 60 years and older who had been hospitalized for HF or had been given a prescription medication for HF were included. Physical frailty was assessed using the following five domains: slowness, weakness, exhaustion, low activity, and shrinking, according to the Cardiovascular Health Study. Patients were divided into nonfrailty and frailty groups according to frailty scores. Plasma BNP level was measured. The 6-min walk test was performed to measure endurance.

Results

Plasma BNP was significantly different between the two groups (frailty group: 158.0 ± 214.7 pg/mL, nonfrailty group: 65.2 ± 88.0 pg/mL, P < 0.01). Multivariate logistic regression analysis revealed log-transformed plasma BNP (Log BNP) was significantly associated with physical frailty (OR: 1.68, 95% CI: 1.11–2.56), and Log BNP was significantly associated with the slowness domain (walking speed < 1.0 m/s) of physical frailty (OR: 1.75, 95% CI: 1.15–2.67). Additionally, Log BNP was negatively correlated to the 6-minute walk distance (6MWD) (ρ = −0.37, P < 0.01), while 6MWD was positively correlated to walking speed (ρ = 0.66, P < 0.01).

Conclusions

Plasma BNP level was related to physical frailty, especially in the slowness domain. Endurance may intervene in the associations between plasma BNP level and walking speed.

Towards clinical applications of selected reaction monitoring for plasma protein biomarker studies

The widespread clinical adoption of protein biomarkers with diagnostic, prognostic and/or predictive value remains a formidable challenge for the biomedical community. From discovery to validation, the path to biomarkers of clinical relevance abounds with many protein candidates, yet so few concrete examples have been substantiated. In this review, we focus on the recent adoption of selected reaction monitoring (SRM) of plasma proteins in the path to clinical use for a broad range of diseases including cancer, cardiovascular disease, genetic disorders and various metabolic disorders. Recent progress reveals a promising outlook for clinical applications using SRM, which now provides the routine analysis of clinically relevant protein markers at low nanogram per millilitre in plasma.

Natriuretic Peptide testing in primary care

The incidence, as well as the morbidity and mortality associated with heart failure (HF) continue to rise despite advances in diagnostics and therapeutics. A recent advance in the diagnostic and therapeutic approach to HF is the use of natriuretic peptide (NP) testing, including both B-type natriuretic peptide (BNP) and its amino terminal cleavage equivalent (NT-proBNP). NPs may be elevated at an early stage among those with symptoms as well among those without. The optimal approach for applying NP testing in general populations is to select the target population and optimal cut off values carefully. Superior diagnostic performance is observed among those with higher baseline risk (such as hypertensives or diabetics). As well, unlike for acute HF, the cut off value for outpatient testing for BNP is 20-40 pg/mL and for NTproBNP it is 100-150 ng/L. In symptomatic primary care patients, both BNP and NT-proBNP serve as excellent tools for excluding HF based on their excellent negative predictive values and their use may be cost effective. Among those with established HF, it is logical to assume that titration of treatment to achieve lower NPs levels may be advantageous. There are several ongoing trials looking at that prospect.

Invasive and noninvasive correlations of B-type natriuretic peptide in patients with heart failure due to Chagas cardiomyopathy

Heart failure due to Chagas cardiomyopathy (HFCC) differs from failure with other etiologies because of the occurrence of intense inflammatory infiltrate and right ventricle compromise. This article investigates correlations of B-type natriuretic peptide (BNP) levels with parameters of severity in HFCC. Twenty-eight patients and 8 normal controls underwent heart catheterization and clinical and laboratory analyses. BNP levels were higher in patients with HFCC (P<.0001) and correlated with New York Heart Association (NYHA) class; right atrial pressure; wedge pressure; cardiac output; levels of serum sodium, hemoglobin, urea, and tumor necrosis factor-alpha; and ejection fraction. Interferon-gamma and transforming growth factor-beta did not correlate with BNP level. The authors conclude that BNP levels are elevated in patients experiencing HFCC, irrespective of NYHA class, and that the occurrence of HFCC correlates with severity of disease.

Plasma brain natriuretic peptide levels, right ventricular volume overload and exercise capacity in adolescents after surgical repair of tetralogy of Fallot

BACKGROUND

Right ventricular (RV) volume overload secondary to pulmonary regurgitation contributes to long-term morbidities in patients after tetralogy of Fallot (TOF) repair. We tested the hypothesis that plasma brain natriuretic peptide (BNP) levels relate to RV volume overload, pulmonary regurgitation, and exercise capacity in adolescents after TOF repair.

METHODS

We assessed the RV function echocardiographically and plasma BNP levels in 32 postoperative TOF patients aged 14.7+/-3.1 years and 20 age-matched controls. Eighteen patients further underwent cardiovascular magnetic resonance imaging and 26 had exercise testing.

RESULTS

Compared with controls, patients had significantly higher BNP levels (p=0.027), greater indexed RV end-diastolic dimension (p<0.001), increased RV myocardial performance index (p=0.005), and reduced tricuspid annular systolic velocity (p=0.008). Multivariate analysis identified indexed RV end-diastolic dimension as the only significant determinant of plasma BNP levels (beta=0.69, p<0.001). Plasma BNP levels correlated positively with indexed RV end-diastolic volume (r=0.6, p=0.009) and pulmonary regurgitant fraction (r=0.54, p=0.026), and negatively with exercise duration (r=-0.45, p=0.021), peak oxygen consumption (r=-0.43, p=0.03), and minute ventilation at maximal exercise (r=-0.52, p=0.006). Multivariate analysis demonstrated BNP levels (beta=-0.43, p=0.034) and body mass index (beta=-0.40, p=0.036) to be independent predictors of peak oxygen consumption. No relations were found between BNP levels and RV myocardial performance index, tricuspid annular velocities and RV ejection fraction.

CONCLUSIONS

In adolescent patients after TOF repair, plasma BNP levels relate to RV volume overload, pulmonary regurgitation and exercise capacity.

Brain natriuretic peptide levels and cardiac functional capacity in patients with dyspnea and isolated diastolic dysfunction

Diastolic heart failure affects approximately 40%-50% of patients presenting with signs and symptoms of heart failure. The aim of this study was to investigate the relationship between brain natriuretic peptide (BNP) levels and functional capacity in patients admitted with dyspnea and diagnosed with isolated diastolic dysfunction. Fifty-four patients (mean age, 57.4 +/- 8.5 years) with class-2 dyspnea with isolated diastolic dysfunction were enrolled. Serum levels of BNP were measured, and peak oxygen consumption (peak VO(2)), anaerobic threshold (AT), and metabolic equivalent (MET) values were determined with a cardiopulmonary exercise test (CPET). There was a negative correlation between BNP levels and exercise duration (P < 0.05, r = -0.304), AT (P < 0.05, r = -0.380), and number of MET (P < 0.05, r = -0.322) determined by CPET. When patients were divided into 2 groups according to BNP levels; BNP < or = 50 pg/mL (n = 40) versus BNP > 50 pg/mL (n = 14) and analyzed, those with BNP levels > 50 pg/mL had lower peak VO(2) (P = 0.05) and anaerobic threshold (P = 0.01) compared with patients with BNP < or = 50 pg/mL. The results suggest that BNP levels provide an indication about the functional capacity determined by CPET in patients admitted with dyspnea and isolated diastolic dysfunction.

Correlates of B-type natriuretic peptide and 6-min walk in heart failure patients

BACKGROUND

B-type natriuretic peptide (BNP) and 6-min walk test (6MWT) are both related to the severity and prognosis in chronic heart failure (CHF), but may reflect different aspects of CHF. We related BNP and 6MWT to left ventricular ejection fraction (LVEF), New York Heart Association functional class (NYHA), and two indices of quality of life (physical subscales): the Minnesota Living with Heart Failure Questionnaire (MLwHFQph) and the RAND-36ph.

METHODS

Plasma BNP and 6MWT were measured at discharge in 229 patients who had been admitted for CHF. LVEF and NYHA were determined, and patients completed the MLwHFQ and RAND-36 questionnaires.

RESULTS

BNP was weakly correlated to LVEF (r=-0.29, P<0.01) and NYHA (r=0.20, P<0.01), but not to MLwHFQph and RAND-36ph. On the other hand, 6MWT is related to MLwHFQph (r=-0.23, P<0.01), RAND-36ph (r=0.52, P<0.01), and NYHA (r=-0.46, P<0.01), but not to LVEF (r=-0.15, P=0.05). There is also no correlation between BNP and 6MWT (r=-0.01, P=0.87).

CONCLUSIONS

The present data show that BNP and 6MWT represent different aspects of the clinical syndrome of CHF. The outcomes of this study suggest that BNP plasma levels are more related to cardiac function, while 6MWT reflects functional capacity and quality of life.

Analytical and Clinical Evaluation of the Bayer ADVIA Centaur Automated B-Type Natriuretic Peptide Assay in Patients with Heart Failure: A Multisite Study

Background: B-Type natriuretic peptide (BNP) is released from the left ventricle of the heart into the circulation in response to ventricular stretching and volume overload. Increased BNP concentrations are associated with heart failure (HF).

Methods: We evaluated the analytical and clinical performance of the Bayer ADVIA Centaur® BNP assay. Studies included precision, analytical correlation (against the Shionogi ShionoRIA™ and Biosite Triage® BNP assays), BNP results for blood collected in plastic tubes containing EDTA vs other collection tubes, high-dose hook effect, detection limits, and interferences. The clinical performance was tested on 2243 blood samples collected from 983 apparently healthy individuals, 538 patients with chronic disease but without HF (renal insufficiency, chronic obstructive pulmonary disease, diabetes, and hypertension), and 722 patients with HF (New York Heart Association classes I-IV).

Results: The ADVIA Centaur assay had total imprecision (CV) of 3.4%, 2.9%, and 2.4% at BNP concentrations of 48, 461, and 1768 ng/L, respectively. The Passing–Bablok correlations to the ShionoRIA and Triage were as follows: ADVIA Centaur = 1.11(ShionoRIA) − 1.19 ng/L (r = 0.98); ADVIA Centaur = 0.78(Triage) + 5.89 ng/L (r = 0.92), respectively. Of the different blood collection tubes, only EDTA plastic tubes (with and without the barrier gel) were acceptable. The lower detection limit was 0.5 ng/L, and there were no interferences from common analytes, other neuropeptides, or unusual antibodies. BNP exhibited different reference intervals according to age and gender. BNP concentrations increased progressively as the severity of HF increased.

Conclusions: The ADVIA Centaur is the first commercially available BNP assay for use on an automated immunochemistry platform. This assay has good analytical and clinical performance characteristics for diagnosing HF.

Cardiac hormones as diagnostic tools in heart failure

In patients with heart failure, plasma levels of atrial natriuretic peptide (ANP), B-type natriuretic peptide (BNP), and the N-terminal fragments of their prohormones (N-ANP and N-BNP) are elevated, because the cardiac hormonal system is activated by increased wall stretch due to increased volume and pressure overload. Patients suspected of having heart failure can be selected for further investigations on the basis of having an elevated plasma concentration of N-ANP, BNP, and N-BNP. High levels of cardiac hormones identify those at greatest risk for future serious cardiovascular events. Moreover, adjusting heart failure treatment to reduce plasma levels of N-BNP may improve outcome. Cardiac hormones are most useful clinically as a rule-out test. In acutely symptomatic patients, a very high negative predictive value is coupled with a relatively high positive predictive value. Measurement of cardiac hormones in patients with heart failure may reduce the need for hospitalizations and for more expensive investigations such as echocardiography. However, there have also been conflicting reports on the diagnostic value of cardiac hormones, they are not specific for any disease, and the magnitude of the effects of age and gender on BNP in the normal subgroup suggests that these parameters need to be considered when interpreting cardiac hormone levels.