Reliability of N-terminal proBNP assay in diagnosis of left ventricular systolic dysfunction within representative and high risk populations

The Role of Serum NT-proBNP for Predicting Left Ventricular Systolic Dysfunction in Hospitalized Patients in Sri Lanka

Background/aims

Only a few studies have addressed the role of NT-proBNP in identifying Left Ventricular Systolic Dysfunction (LVSD) in South Asian populations. Therefore, the current study was aimed at assessing the use of serum NT-proBNP in predicting LVSD in a hospitalized population in Sri Lanka.

Methods

A random sample of 278 individuals referred for echocardiography at a major Teaching Hospital consented for venous blood samples to be collected for serum NT-proBNP assay by sandwich ELISA. Based on the ejection fraction (LVEF) and fractional shortening (FS), participants were differentiated as LVSD (LVEF<50%, FS≤ 29%) and non-LVSD individuals (LVEF>60%). According to inclusion/exclusion criteria, the final study sample consisted of 100 LVSD patients and 41 non-LVSD individuals.

Results

The mean ages of the LVSD and non-LVSD groups were 69.1 (±6.2 years) and 71.4 (±2.4 years) (p=0.066) respectively. The median NT-proBNP value (with IQR) among LVSD patients (528.2 pg/mL,355.2-924.2) was comparatively higher than that of non-LVSD individuals (207.3 pg/mL,177.5-343.0). Strong correlations of NT-proBNP level with LVEF (Spearman rho= -0.84, p<0.001) and FS (rho= -0.81, p<0.001) suggested that serum NT-proBNP concentration increases in parallel to deteriorating left ventricular functions. The AUROC of serum NT-proBNP for differentiating LVSD was 0.859 (95% CI:0.79 - 0.92) and the optimal cut-off level for predicting LVSD was 265pg/mL, with 90% sensitivity and 70% specificity.

Conclusion

Current Sri Lankan study revealed a considerable correlation of serum NT-proBNP level with LVSD and utilizing such an assay for screening will facilitate adequate evidence to rule-out LVSD among high-risk residents.

Diagnostic accuracy of natriuretic peptide screening for left ventricular systolic dysfunction in the community: systematic review and meta-analysis

AIMS

Heart failure (HF) is a global health burden and new strategies to achieve timely diagnosis and early intervention are urgently needed. Natriuretic peptide (NP) testing can be used to screen for left ventricular systolic dysfunction (LVSD), but evidence on test performance is mixed, and international HF guidelines differ in their recommendations. Our aim was to summarize the evidence on diagnostic accuracy of NP screening for LVSD in general and high-risk community populations and estimate optimal screening thresholds.

METHODS

We searched relevant databases up to August 2020 for studies with a screened community population of over 100 adults reporting NP performance to diagnose LVSD. Study inclusion, quality assessment, and data extraction were conducted independently and in duplicate. Diagnostic test meta-analysis used hierarchical summary receiver operating characteristic curves to obtain estimates of pooled accuracy to detect LVSD, with optimal thresholds obtained to maximize the sum of sensitivity and specificity.

RESULTS

Twenty-four studies were identified, involving 26 565 participants: eight studies in high-risk populations (at least one cardiovascular risk factor), 12 studies in general populations, and four in both high-risk and general populations combined. For detecting LVSD in screened high-risk populations with N-terminal prohormone brain natriuretic peptide (NT-proBNP), the pooled sensitivity was 0.87 [95% confidence interval (CI) 0.73-0.94] and specificity 0.84 (95% CI 0.55-0.96); for BNP, sensitivity was 0.75 (95% CI 0.65-0.83) and specificity 0.78 (95% CI 0.72-0.84). Heterogeneity between studies was high with variations in positivity threshold. Due to a paucity of high-risk studies that assessed NP performance at multiple thresholds, it was not possible to calculate optimal thresholds for LVSD screening in high-risk populations alone. To provide an indication of where the positivity threshold might lie, the pooled accuracy for LVSD screening in high-risk and general community populations were combined and gave an optimal cut-off of 311 pg/mL [sensitivity 0.74 (95% CI 0.53-0.88), specificity 0.85 (95% CI 0.68-0.93)] for NT-proBNP and 49 pg/mL [sensitivity 0.68 (95% CI 0.45-0.85), specificity 0.81 (0.67-0.90)] for BNP.

CONCLUSIONS

Our findings suggest that in high-risk community populations NP screening may accurately detect LVSD, potentially providing an important opportunity for diagnosis and early intervention. Our study highlights an urgent need for further prospective studies, as well as an individual participant data meta-analysis, to more precisely evaluate diagnostic accuracy and identify optimal screening thresholds in specifically defined community-based populations to inform future guideline recommendations.

Assessment of the impact of different N terminal pro brain natriuretic peptide thresholds on echocardiography services

Aims

N terminal pro brain natriuretic peptide (NT‐proBNP) is considered a rule‐out test for patients with suspected heart failure. The NT‐proBNP thresholds recommended for echocardiography by the European Society of Cardiology (ESC) and National Institute for Health and Care Excellence (NICE) are based on small studies of patients with heart failure and left ventricular (LV) systolic dysfunction (LVSD). The purpose of our study was to examine the relation between NT‐proBNP and LVSD in a larger number of patients with symptoms suggestive of heart failure in a non‐acute setting.

Methods and results

One thousand patients with suspected chronic heart failure underwent echocardiography within 6 months of NT‐proBNP measurement. NT‐proBNP was the strongest predictor of any form of LVSD in univariate (OR 2.52, 95% CI 2.19–2.91, P value < 0.001) and multivariate (OR 2.73, 95% CI 2.32–3.21, P value < 0.001) analyses. Negative predictive value (NPV) of NT‐proBNP for impaired LV systolic function (ejection fraction 35–49%) was 98% at 125 pg/mL (the ESC threshold), 93% at 400 pg/mL (the NICE threshold), 91% at 1000 pg/mL and 90% at 2000 pg/mL. Corresponding values for severe LVSD (ejection fraction <35%) were 100%, 99%, 98% and 96%. The number of patients per 1000 with suspected chronic heart failure requiring echocardiography at each threshold was 851, 543, 324, and 182, respectively.

Conclusions

N terminal pro brain natriuretic peptide thresholds recommended by ESC and NICE result in large numbers of patients with suspected chronic heart failure being referred for echocardiography. Raising the NT‐proBNP threshold would improve access to echocardiography with minimal negative impact on the clinical performance of this cardiac biomarker.

Prospective evaluation and long-term follow-up of patients referred to secondary care based upon natriuretic peptide levels in primary care

AIMS

The UK National Institute for Health and Care Excellence (UK-NICE) and European Society of Cardiology (ESC) guidelines advise natriuretic peptide (NP) assessment in patients presenting to primary care with symptoms possibly due to chronic heart failure (HF), to determine need for specialist involvement. This prospective service evaluation aimed to describe the diagnostic and prognostic utility of these guidelines.

METHODS AND RESULTS

We prospectively collected clinical, echocardiography and outcomes data (minimum 5 years) from all patients referred to the Leeds HF Service for 12 months of following the initiation of the NP-guideline-directed pathway. Between 1 May 2012 and 1 August 2013, 1020 people with symptoms possibly due to HF attended either with a raised NT-pro-BNP or a previous myocardial infarction (MI) with an overall rate of left ventricular systolic dysfunction (LVSD) of 33%. Of these, 991 satisfied the ESC criteria (NT-pro-BNP ≥125 pg/mL) in whom the rate of LVSD was 32%, and 821 the UK-NICE criteria in whom the rate of LVSD was 49% in those with a previous MI, 25% in those with NT-pro-BNP concentration 400-2000 pg/mL, and 54% in those with NT-pro-BNP concentration of >2000 pg/mL. An NT-pro-BNP concentration 125-400 pg/mL had a 12% risk of LVSD. Specificity was poor in women >70 years, who made up the largest proportion of attendees. Elevated NT-pro-BNP levels were associated with lower survival even in the absence of LVSD.

CONCLUSION

In people referred through the ESC and UK-NICE guidelines, elevated NT-pro-BNP is a marker of increased mortality risk, but there is wide variation in specificity for LVSD. Age- and sex-adjusted criteria might improve performance.

An Appraisal of Biomarker-Based Risk-Scoring Models in Chronic Heart Failure: Which One Is Best?

PURPOSE OF REVIEW

While prediction models incorporating biomarkers are used in heart failure, these have shown wide-ranging discrimination and calibration. This review will discuss externally validated biomarker-based risk models in chronic heart failure patients assessing their quality and relevance to clinical practice.

RECENT FINDINGS

Biomarkers may help in determining prognosis in chronic heart failure patients as they reflect early pathologic processes, even before symptoms or worsening disease. We present the characteristics and describe the performance of 10 externally validated prediction models including at least one biomarker among their predictive factors. Very few models report adequate discrimination and calibration. Some studies evaluated the additional predictive value of adding a biomarker to a model. However, these have not been routinely assessed in subsequent validation studies. New and existing prediction models should include biomarkers, which improve model performance. Ongoing research is needed to assess the performance of models in contemporary patients.

Role of Biomarkers for the Prevention, Assessment, and Management of Heart Failure: A Scientific Statement From the American Heart Association

BACKGROUND AND PURPOSE

Natriuretic peptides have led the way as a diagnostic and prognostic tool for the diagnosis and management of heart failure (HF). More recent evidence suggests that natriuretic peptides along with the next generation of biomarkers may provide added value to medical management, which could potentially lower risk of mortality and readmissions. The purpose of this scientific statement is to summarize the existing literature and to provide guidance for the utility of currently available biomarkers.

METHODS

The writing group used systematic literature reviews, published translational and clinical studies, clinical practice guidelines, and expert opinion/statements to summarize existing evidence and to identify areas of inadequacy requiring future research. The panel reviewed the most relevant adult medical literature excluding routine laboratory tests using MEDLINE, EMBASE, and Web of Science through December 2016. The document is organized and classified according to the American Heart Association to provide specific suggestions, considerations, or contemporary clinical practice recommendations.

RESULTS

A number of biomarkers associated with HF are well recognized, and measuring their concentrations in circulation can be a convenient and noninvasive approach to provide important information about disease severity and helps in the detection, diagnosis, prognosis, and management of HF. These include natriuretic peptides, soluble suppressor of tumorgenicity 2, highly sensitive troponin, galectin-3, midregional proadrenomedullin, cystatin-C, interleukin-6, procalcitonin, and others. There is a need to further evaluate existing and novel markers for guiding therapy and to summarize their data in a standardized format to improve communication among researchers and practitioners.

CONCLUSIONS

HF is a complex syndrome involving diverse pathways and pathological processes that can manifest in circulation as biomarkers. A number of such biomarkers are now clinically available, and monitoring their concentrations in blood not only can provide the clinician information about the diagnosis and severity of HF but also can improve prognostication and treatment strategies.

Primary care REFerral for EchocaRdiogram (REFER) in heart failure: a diagnostic accuracy study

BACKGROUND

Symptoms of breathlessness, fatigue, and ankle swelling are common in general practice but deciding which patients are likely to have heart failure is challenging.

AIM

To evaluate the performance of a clinical decision rule (CDR), with or without N-Terminal pro-B type natriuretic peptide (NT-proBNP) assay, for identifying heart failure.

DESIGN AND SETTING

Prospective, observational, diagnostic validation study of patients aged >55 years, presenting with shortness of breath, lethargy, or ankle oedema, from 28 general practices in England.

METHOD

The outcome was test performance of the CDR and natriuretic peptide test in determining a diagnosis of heart failure. The reference standard was an expert consensus panel of three cardiologists.

RESULTS

Three hundred and four participants were recruited, with 104 (34.2%; 95% confidence interval [CI] = 28.9 to 39.8) having a confirmed diagnosis of heart failure. The CDR+NT-proBNP had a sensitivity of 90.4% (95% CI = 83.0 to 95.3) and specificity 45.5% (95% CI = 38.5 to 52.7). NT-proBNP level alone with a cut-off <400 pg/ml had sensitivity 76.9% (95% CI = 67.6 to 84.6) and specificity 91.5% (95% CI = 86.7 to 95.0). At the lower cut-off of NT-proBNP <125 pg/ml, sensitivity was 94.2% (95% CI = 87.9 to 97.9) and specificity 49.0% (95% CI = 41.9 to 56.1).

CONCLUSION

At the low threshold of NT-proBNP <125 pg/ml, natriuretic peptide testing alone was better than a validated CDR+NT-proBNP in determining which patients presenting with symptoms went on to have a diagnosis of heart failure. The higher NT-proBNP threshold of 400 pg/ml may mean more than one in five patients with heart failure are not appropriately referred. Guideline natriuretic peptide thresholds may need to be revised.

Performance of BNP and NT-proBNP for diagnosis of heart failure in primary care patients: a systematic review

National and international guidelines have been published recommending the use of natriuretic peptides as an aid to the diagnosis of heart failure (HF) in acute settings; however, few specific recommendations exist for governing the use of these peptides in primary care populations. To summarize the available data relevant to the diagnosis of HF in primary care patient population, we systematically reviewed the literature to identify original articles that investigated the diagnostic accuracy of B-type natriuretic peptide (BNP) and N-terminal proBNP (NT-proBNP) in primary care settings. The search yielded 25,864 articles in total: 12 investigating BNP and 20 investigating NT-proBNP were relevant to our objective and included in the review. QUADAS-2 and GRADE were used to assess the quality of the included articles. Diagnostic data were pooled based on three cutpoints: lowest and optimal, as chosen by study authors, and manufacturers' suggested. The effect of various determinants (e.g., age, gender, BMI, and renal function) on diagnostic performance was also investigated. Pooled sensitivity and specificity of BNP and NT-proBNP using the lowest [0.85 (sensitivity) and 0.54 (specificity)], optimal (0.80 and 0.61), and manufacturers' (0.74 and 0.67) cutpoints showed good performance for diagnosing HF. Similar performance was seen for NT-proBNP: lowest (0.90 and 0.50), optimal (0.86 and 0.58), and manufacturers' (0.82 and 0.58) cutpoints. Overall, we rated the strength of evidence as high because further studies will be unlikely to change the estimates diagnostic performance.

The potential role of NT-proBNP in screening for and predicting prognosis in heart failure: a survival analysis

OBJECTIVE

To determine the potential role of N-terminal pro-B-type natriuretic peptide (NT-proBNP) in screening for and predicting prognosis in heart failure by examining diagnosis and survival of patients with a raised NT-proBNP at screening.

DESIGN

Survival analysis.

SETTING

Prospective substudy of the Echocardiographic Heart of England Screening study (ECHOES) to investigate 10-year survival in participants with an NT-proBNP level at baseline.

PARTICIPANTS

594 participants took part in the substudy. Records of all participants in the ECHOES cohort were flagged during the screening phase which ended on 25 February 1999. All deaths until 25 February 2009 were coded.

OUTCOME MEASURES

Logistic regression was used to examine whether NT-proBNP is useful in predicting heart failure at screening after adjustment for age, sex and cohort. Kaplan-Meier curves and log rank tests were used to compare survival times of participants according to NT-proBNP level. Cox regression was carried out to assess the prognostic effect of NT-proBNP after allowing for significant covariates and receiver operator curves were used to determine test reliability.

RESULTS

The risk of heart failure increased almost 18-fold when NT-proBNP was 150 pg/mL or above (adjusted OR=17.7, 95% CI 4.9 to 63.5). 10-year survival in the general population cohort was 61% (95% CI 48% to 71%) for those with NT-proBNP ≥150 pg/mL and 89% (95% CI 84% to 92%) for those below the cut-off at the time of the initial study. After adjustment for age, sex and risk factors for heart failure, NT-proBNP level ≥150 pg/mL was associated with a 58% increase in the risk of death within 10 years (adjusted HR=1.58, 95% CI 1.09 to 2.30).

CONCLUSIONS

Raised NT-proBNP levels, when screening the general population, are predictive of a diagnosis of heart failure (at a lower threshold than guidelines for diagnosing symptomatic patients) and also predicted reduced survival at 10 years.

Heart failure therapy in patients with coronary artery disease

Heart failure and coronary artery disease share many risk factors. Coronary artery disease often pre-dates the development of heart failure with reduced ejection fraction. A diagnosis of heart failure should be considered in any patient with a history of coronary artery disease who presents with breathlessness, ankle oedema or fatigue. Several therapies, such as renin-angiotensin antagonists and B blockers, have been proven to improve survival in patients with heart failure with reduced ejection fraction but evidence for effectiveness in heart failure with preserved ejection fraction is lacking. The management of heart failure and coronary artery disease overlaps considerably but can also be conflicting. Optimal risk factor management is key to preventing progression to heart failure in patients with coronary artery disease.

The REFER (REFer for EchocaRdiogram) protocol: a prospective validation of a clinical decision rule, NT-proBNP, or their combination, in the diagnosis of heart failure in primary care. Rationale and design

BACKGROUND

Heart failure is a major cause of mortality and morbidity. As mortality rates are high, it is important that patients seen by general practitioners with symptoms suggestive of heart failure are identified quickly and treated appropriately. Identifying patients with heart failure or deciding which patients need further tests is a challenge. All patients with suspected heart failure should be diagnosed using objective tests such as echocardiography, but it is expensive, often delayed, and limited by the significant skill shortage of trained echocardiographers. Alternative approaches for diagnosing heart failure are currently limited. Clinical decision tools that combine clinical signs, symptoms or patient characteristics are designed to be used to support clinical decision-making and validated according to strict methodological procedures. The REFER Study aims to determine the accuracy and cost-effectiveness of our previously derived novel, simple clinical decision rule, a natriuretic peptide assay, or their combination, in the triage for referral for echocardiography of symptomatic adult patients who present in general practice with symptoms suggestive of heart failure.

METHODS/DESIGN

This is a prospective, Phase II observational, diagnostic validation study of a clinical decision rule, natriuretic peptides or their combination, for diagnosing heart failure in primary care. Consecutive adult primary care patients 55 years of age or over presenting to their general practitioner with a chief complaint of recent new onset shortness of breath, lethargy or peripheral ankle oedema of over 48 hours duration, with no obvious recurrent, acute or self-limiting cause will be enrolled. Our reference standard is based upon a three step expert specialist consensus using echocardiography and clinical variables and tests.

DISCUSSION

Our clinical decision rule offers a potential solution to the diagnostic challenge of providing a timely and accurate diagnosis of heart failure in primary care. Study results will provide an evidence-base from which to develop heart failure care pathway recommendations and may be useful in standardising care. If demonstrated to be effective, the clinical decision rule will be of interest to researchers, policy makers and general practitioners worldwide.

TRIAL REGISTRATION

ISRCTN17635379.

[Validity and usefulness of B-type natriuretic peptide (BNP) for early detection of left ventricular dysfunction in high-risk patients in primary care]

OBJECTIVE

The aim of this study was to determine the accuracy of BNP test for early diagnosis of left ventricular dysfunction in patients at high-risk for heart failure.

DESIGN

Cross-sectional descriptive study.

SETTING

7 Primary Care Centres in Madrid (Spain).

PARTICIPANTS

A consecutive sample of 204 consecutive asymptomatic patients with high risk for heart failure (Stages A-B, AHA/ACC Classification).

MAIN MEASUREMENTS

BNP plasma levels were measured in the clinical setting using Triage BNP Test(®) (Biosite(®)) and an echocardiography was performed in the following 3 days in a single hospital unit as a reference standard. Plasma BNP levels were compared depending on the presence/absence of left ventricular dysfunction (LVD), type and severity degree. Sensitivity, specificity, positive and negative predictive values, and Área under the receiver operating characteristic curve (ROC) for BNP assay were calculated.

RESULTS

BNP values were significantly higher (P<.001) in patients with left ventricular systolic dysfunction (LVSD). No significant differences were found for diastolic dysfunction. The best cut-off value to discriminate the patients with LVSD was 71.00 pg/ml, with an Área under the ROC curve of 0.757 (95% CI 0.64-0.87). Sensitivity for LVD diagnosis was 75% (95% CI 50.66-99.34), specificity 70.19% (95% CI 62.81-77.57), positive predictive value (PPV) 20% (95% CI 9.05-30.95), and negative predictive value (NPV) 96.58% (95% CI 92.86-100), with LVSD prevalence of 9.04% in this population.

CONCLUSIONS

BNP determinations are of value in diagnosing LVSD in a primary care setting, with similar sensitivities and specificities. Due to the high NPV is useful to rule-out patients for echocardiography.

Natriuretic Peptides and Assessment of Cardiovascular Disease Risk in Asymptomatic Persons

Current tools for cardiovascular disease (CVD) risk assessment in asymptomatic individuals are imperfect. Preventive measures aimed only at individuals deemed high risk by current algorithms neglect large numbers of low-risk and intermediate-risk individuals who are destined to develop CVD and who would benefit from early and aggressive treatment. Natriuretic peptides have the potential both to identify individuals at risk for future cardiovascular events and to help detect subclinical CVD. Choosing the appropriate subpopulation to target for natriuretic peptide testing will help maximize the performance and the cost effectiveness. The combined use of multiple risk markers, including biomarkers, genetic testing, and imaging or other noninvasive measures of risk, offers promise for further refining risk assessment algorithms. Recent studies have highlighted the utility of natriuretic peptides for preoperative risk stratification; however, cost effectiveness and outcomes studies are needed to affirm this and other uses of natriuretic peptides for cardiovascular risk assessment in asymptomatic individuals.

Natriuretic peptides in the detection of preclinical diastolic or systolic dysfunction

AIMS

The diagnostic value of natriuretic peptides in asymptomatic patients at risk for diastolic or systolic HF is controversial. We tested (1) the prevalence of preclinical LV dysfunction in an at-risk cohort; (2) the diagnostic accuracy of natriuretic peptides alone or in combination with clinical parameters for predicting asymptomatic left ventricular systolic or diastolic dysfunction.

METHODS

542 primary care patients (mean age 63 +/- 11 years, 42% female) without prediagnosed HF, but with risk factors for left ventricular dysfunction, underwent thorough cardiological workup, including echocardiography and analysis of natriuretic peptides.

RESULTS

23 patients (4%) showed reduced systolic function (EF < 50%), and 15 patients (3%) had severe diastolic dysfunction. All natriuretic peptides significantly increased with decreasing ejection fraction and with increasing degree of diastolic dysfunction. For natriuretic peptides, receiver operating characteristics analysis yielded good results for the detection of systolic dysfunction or severe diastolic dysfunction. Combining clinical parameters with natriuretic peptide data improved the diagnostic accuracy and largely reduced the number of needed screening echoes to identify patients with LV systolic or diastolic dysfunction.

CONCLUSIONS

The prevalence of preclinical diastolic dysfunction is high in primary care patients at risk, but the relative prevalence of severe diastolic dysfunction and systolic dysfunction is only 7%. High-risk individuals may be screened most efficiently by using a score system incorporating clinical data and NT-proBNP.

N-terminal pro-B-type natriuretic peptide: an independent marker for coronary artery disease in asymptomatic diabetic patients

AIMS

To determine whether plasma N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels, a marker for cardiac failure and potentially for the severity of coronary artery disease (CAD), predicts silent myocardial ischaemia (SMI) and silent CAD in asymptomatic high-risk diabetic patients.

METHODS

Five hundred and seventeen asymptomatic diabetic patients with > or = 1 additional cardiovascular risk factor but without heart failure were prospectively screened between 1998 and 2008 for SMI, defined as an abnormal stress myocardial scintigraphy, and subsequently for significant (> 70%) angiographic CAD. The 323 patients with interpretable echocardiography and for whom NT-proBNP was measured were included in this analysis.

RESULTS

SMI was found in 108 (33.4%) patients, 39 of whom had CAD. NT-proBNP was higher in the patients with CAD than in the patients without CAD [45.0 (1-3199) vs. 20.0 (1-1640) pg/ml; P < 0.0001 median (range)], even after adjustment for confounding factors: age, gender, body mass index, glycated haemoglobin (HbA(1c)), retinopathy, nephropathy, hypertension, echocardiographic parameters (P < 0.05). NT-proBNP in the third tertile (> or = 38 pg/ml) predicted CAD with a sensitivity of 59% and a specificity of 67%. In a multiple logistic regression analysis including NT-proBNP > or = 38 pg/ml, age, body mass index, gender, HbA(1c), hypertension, retinopathy, nephropathy, peripheral occlusive arterial disease, left ventricular systolic dysfunction, dilatation and hypertrophy and Type 1 transmitral flow, NT-proBNP > or = 38 pg/ml was the only significant independent predictor of silent CAD [odds ratio (OR) 3.1 (95% confidence interval 1.3-7.6), P = 0.015].

CONCLUSIONS

NT-proBNP measurement helps to better define asymptomatic diabetic patients with an increased likelihood for CAD, independently of cardiac function and structure.

Natriuretic peptide as an adjunctive diagnostic test in the acute phase of Kawasaki disease

Coronary arteritis rather than myocardial involvement is typically emphasized in Kawasaki disease (KD). Moreover, the criteria and the usual biological markers oversee the importance of cardiac-specific markers in diagnosing this disease. We sought to study the clinical usefulness of measuring B-type natriuretic peptide (BNP) and its N-terminal moiety (NT-proBNP) at the onset of KD. Our objective was to evaluate blood concentrations of BNP and NT-proBNP during the acute and subacute phases of KD. We conducted a prospective study comparing newly diagnosed KD patients to non-KD febrile controls. Blood specimens were collected at presentation, 6-12 h after intravenous immunoglobulin (IVIG) therapy, 1-2 weeks later, and 2-3 months later, or only upon reenrollment for controls. Forty-there KD and 19 control patients were enrolled consecutively. The mean age was 47.1 +/- 34.3 and 62.2 +/- 44.9 months, respectively (p = NS). Pre-IVIG NT-proBNP levels were significantly higher in KD patients than in controls (923.6 +/- 1361.7 vs. 186.2 +/- 198.0 ng/L; p < 0.001), with no statistical difference for BNP (141.9 +/- 227.5 vs. 59.9 +/- 72.4 ng/L; p = 0.112). In conclusion, our data indicate that NT-proBNP is a better marker of myocardial involvement in acute KD than BNP, particularly in cases with incomplete diagnostic criteria, and suggest that it may be a valid adjunctive diagnostic method to support the diagnosis of KD.

Amino-terminal pro-brain natriuretic peptid in prediction of left ventricular ejection fraction

We aimed to evaluate levels of amino-terminal pro-brain natriuretic peptid (NT-proBNP) in prediction of left ventricular ejection fraction (LVEF) in heart failure patients. Prospective study on 60 consecutive patients with symptoms and signs of heart failure was performed. Blood samples for NT-proBNP analysis was taken from all test subjects and echocardiography was also done in all of them. According to LVEF value, patients were divided into four groups; those with <or=30%, 31 to 39%, 40 to 49% and >or=50%. NT-proBNP values correlated with LVEF value. Regression analysis was used to evaluate how well NT-proBNP values predict LVEF. We used Receiver Operating Characteristic Curve calculation to evaluate diagnostic performance of NT-proBNP in estimation of LVEF. Average value of NT-proBNP in test group was 3191.69+/-642.89 pg/ml (p<0.001). Average value of NT-proBNP decreased with higher LVEF categories with significant (p<0.001) and high negative correlation (r= -0,75). Stepwise multivariate linear regression analysis showed that logarithmic value of NT-proBNP was excellent predictor of LVEF value (p<0.05). Model equation based on regression analysis was LVEF=88.645-15.311 x log (NT-proBNP). Predictive model for LVEF yielded from regression analysis had sensitivities of 98% and 81%, specificities of 20% and 90%, positive predictive values of 86% and 78% and negative predictive values of 67% and 92% for predicting patients with LVEF<50% and LVEF<40%, respectively. There was negative linear correlation between NT-proBNP and LVEF. NT-proBNP was excellent predictor of LVEF value (p<0.05).

Identification and guided treatment of ventricular dysfunction in general practice using blood B-type natriuretic peptide

BACKGROUND

B-type natriuretic peptide (BNP) is a blood test which detects ventricular wall stretch and is being increasingly used in primary care on limited evidence.

AIM

To assess the practical implications and potential clinical benefit of measuring BNP to identify and guide the treatment of undiagnosed or under-treated ventricular dysfunction in at-risk patients.

DESIGN OF STUDY

Screening study with single-arm intervention.

SETTING

A total of 1918 patients with diabetes mellitus or ischaemic heart disease aged > or =65 years registered with 12 general practices were invited; 76 patients with elevated BNP underwent BNP-guided treatment titration.

METHOD

Eligible patients were invited to attend for a blood test at their own practice; those with a persistently elevated plasma BNP concentration (>43.3 pmol/l) after repeat measurement were offered initiation or up-titration of treatment guided by remeasurement of BNP with a target concentration of <36 pmol/l.

RESULTS

Seven-hundred and fifty-nine patients (40%) attended for screening; 76 (10% of 759) commenced treatment titration. Of these 76 patients, 64 (84%) were asymptomatic or had only mild breathlessness. Maximum titration effect was achieved by the second visit when 27 (36%) had achieved the BNP target concentration and the mean reduction was 10.8 pmol/l (P<0.001). The most effective therapeutic step was a switch in beta-blocker to carvedilol or bisoprolol (P<0.001).

CONCLUSION

About 10% of patients with diabetes or cardiovascular disease on GP morbidity registers have a persistently raised plasma BNP concentration. Simple adjustment of their drug treatment may reduce their BNP and associated mortality risk, but further up-titration against BNP is only possible if the within-person biological variability of measurement can be reduced.

BNP or NTproBNP? A clinician's perspective

Existing literature on two natriuretic peptides--B-type natriuretic peptide (BNP) and amino terminal pro-brain natriuretic peptide (NTproBNP)--is overwhelming. Both peptides are acknowledged markers for cardiac dysfunction. Most of the sources present data on either BNP or NTproBNP making the comparison difficult. This paper focuses on reviewing studies directly comparing two peptides in the setting of chronic and acute heart failure (HF) and coronary artery disease. Many concomitant diseases influence these two peptides to varying extent. These characteristics should be taken into consideration when interpreting results. For most practical purposes, BNP and NTproBNP are interchangeable, and can be used based on local preferences and availability. NTproBNP seems to be more advantageous for diagnosing mild HF or asymptomatic left ventricular dysfunction.

Evidence for the use of B-type natriuretic peptides for screening asymptomatic populations and for diagnosis in primary care

OBJECTIVES

To determine the screening and diagnostic properties of BNP and NT-proBNP for heart failure in primary care.

DESIGN AND METHODS

We conducted a systematic review of randomized control trials and observational (cohort or case-control) studies of heart failure detection using B-type natriuretic peptides published in English from January 1989 to February 2005. We extracted or calculated sensitivity, specificity, positive and negative likelihood ratios, area under the receiver-operator characteristic curve and diagnostic odds ratio (DOR).

RESULTS

We included 17 studies (7 screening, 9 diagnosis in primary care or specialised clinic, 1 both). There was considerable heterogeneity within the study populations, reference standard for diagnosis, and B-type natriuretic peptide decision point. Sensitivity ranged from 26% to 98%; and specificity from 44% to 88%. For screening, the Diagnostic Odds Ratio (DOR) ranged from 2.7 to 29, and for diagnosis from 2.8 to 137.

CONCLUSIONS

The performance characteristics of B-type natriuretic peptides measurement are not suitable for screening asymptomatic patients. For diagnosis in primary care, low B-type natriuretic peptide values may be used to rule-out heart failure but, due to poor specificity, high values cannot be used to rule-in the condition.

B-type natriuretic peptide and its molecular precursor in myocardial infarction complicated by cardiogenic shock

BACKGROUND

Plasma measurement of cardiac natriuretic peptides and their biosynthetic precursors is helpful in chronic heart failure patients. In contrast, information on circulating B-type natriuretic peptide (BNP) and its molecular precursor (proBNP) in patients with cardiogenic shock is scarce. We therefore examined proBNP-derived peptides in plasma from patients with myocardial infarction complicated by cardiogenic shock.

METHODS AND RESULTS

Patients were referred for early, invasive therapy because of myocardial infarction complicated by cardiogenic shock (n = 13). Plasma proBNP was measured with an automated assay (NT-proBNP) and an in-house radioimmunoassay (proBNP); BNP concentrations were quantitated with an immunoradiometric assay. The median NT-proBNP concentration was 8.2-fold higher than the corresponding BNP concentration (873 pmol/L [range 41-12,486] versus 107 pmol/L [1-1041], P < .001). Moreover, the NT-proBNP concentration was 3.3-fold higher compared with proBNP (268 pmol/L [19-12,220], P < .01). Despite the molar differences, there was a strong correlation between NT-proBNP and proBNP (r = 0.84, P < .0001) and BNP (r = 0.82, P < .0001) concentrations. Gel filtration chromatography suggested that the proBNP immunoreactivity reflect a molecular form larger than the N-terminal 1-76 fragment.

CONCLUSIONS

The study reveals the plasma profile of proBNP-derived peptides during myocardial infarction complicated by cardiogenic shock. Peripheral concentrations of NT-proBNP, proBNP, and BNP were highly correlated despite marked differences between assays. The results also suggest an increase in cardiac proBNP processing after myocardial infarction and cardiogenic shock.

Comparison of brain natriuretic peptide (BNP) and amino-terminal ProBNP for early diagnosis of heart failure

BACKGROUND

We compared the diagnostic accuracy of brain natriuretic peptide (BNP) and amino-terminal proBNP (NT-proBNP) for diagnosis of preclinical and mild heart failure (HF).

METHODS

We assayed plasma NT-proBNP and BNP in 182 healthy controls and in a prospective cohort of 820 HF patients divided according to the American Heart Association/American College of Cardiology classification. These included 86 patients in stage A [mean (SE) ejection fraction 61% (1%); mean (SE) age 47 (2) years], 255 in stage B [65% (2%); 62 (1) years], 420 patients in stage C [35% (1%); 68 (1) years] and 59 in stage D [25% (1%); 74 (1) years]. Diagnostic accuracies of BNP and NT-proBNP were evaluated by ROC analysis, and a multivariate linear regression model was applied to predict HF staging.

RESULTS

Median BNP and NT-proBNP concentrations increased from stage A to D 57-fold and 107-fold, respectively. Both assays were accurate (P <0.001) in separating stage B from controls or stage A, and stage C from controls or stage A or B. NT-proBNP was more accurate (P <0.001) than BNP in differentiating stage C from stages A and B patients and controls and was a better predictor of HF classification in a model including age, sex, and renal function (P <0.001).

CONCLUSIONS

Monitoring BNP or NT-proBNP enabled identification of asymptomatic patients at risk for the development of HF. NT-proBNP showed better accuracy than BNP for identifying mild HF.

Comparison of the Diagnostic Accuracy of Brain Natriuretic Peptide (BNP) and the N-Terminal Part of the Propeptide of BNP Immunoassays in Chronic and Acute Heart Failure: A Systematic Review

Background: We used evidence-based laboratory medicine principles to compare the diagnostic accuracy of brain natriuretic peptide (BNP) and the N-terminal part of the propeptide of BNP (NT-proBNP) assays for the diagnosis of heart failure.

Methods: In May 2006, we performed a computerized literature search of the online National Library of Medicine to select studies specifically designed to compare the diagnostic accuracy of BNP and NT-proBNP assays. The comparison took into account the area under the curve and diagnostic odds ratio (DOR) derived from ROC analysis of original studies.

Results: Both BNP and NT-proBNP assays were found to be clinically useful for the diagnosis of heart failure. Metaanalysis of these data was difficult because of the heterogeneity of data regarding patient population, diagnostic criteria, end-points, and immunoassay methods for both BNP and NT-proBNP. Separate metaanalyses were performed for acute and chronic heart failure. In chronic heart failure, the diagnostic DOR for BNP (8.44, 95% CI 4.66–15.30) was not significantly different from that of NT-proBNP (23.36, 95% CI 9.38–58.19). In patients with acute heart failure, the mean DOR for BNP (16.46, 95% CI 10.65–25.43) was not significantly different from that of NT-proBNP (18.61, 95% CI 12.99–26.65).

Conclusion: Our results indicate that both BNP and NT-proBNP assays have a high degree of diagnostic accuracy and clinical relevance for both acute and chronic heart failure.

Hyperhomocysteinemia and Myocardial Expression of Brain Natriuretic Peptide in Rats

Background: Hyperhomocysteinemia (HHcy) has been linked to impaired left ventricular function and clinical class in patients with chronic heart failure. We hypothesized that HHcy stimulates myocardial brain natriuretic peptide (BNP) expression and induces adverse left ventricular remodeling.

Methods: We randomized 50 rats into 5 groups. Groups Co1 and Co2 (controls) received a typical diet. Groups Meth, Hcy1, and Hcy2 were fed the same diet supplemented with 2.4% methionine, 1% homocystine, and 2% homocystine, respectively. After 12 weeks, we measured total plasma homocysteine (tHcy) and BNP in plasma and tissue, and we performed histomorphometric analyses.

Results: All animals had comparable baseline body weight [mean (SD) 234 (26) g] and total circulating Hcy [4.7 (1.7) μmol/L]. After 12 weeks of treatment, total circulating Hcy increased in Meth, Hcy1, and Hcy2 [27.3 (8.8), 40.6 (7.0), and 54.0 (46.0) μmol/L, respectively] and remained unchanged in Co1 and Co2. Serum BNP significantly increased in 1 of 10 animals in Meth, 3 of 10 animals in Hcy1, and 3 of 10 animals in Hcy2. Median (25th–75th percentile) BNP tissue concentrations in Hcy1 and Hcy2 were 55% higher than in the corresponding controls [Co1 vs Hcy1, 225 (186–263) vs 338 (262–410) pg/mg protein, P = 0.05; Co2 vs Hcy2, 179 (107–261) vs 308 (192–429) pg/mg protein, P = 0.12]. In the Meth group, BNP expression was comparable to that of controls [200 (159–235) vs 225 (186–263) pg/mg protein, P = 0.32]. The percentage of perivascular and interstitial collagen and mast cell infiltration were comparable in all groups, indicating no adverse cardiac remodeling.

Conclusion: Three months of intermediate HHcy stimulated increased cardiac BNP expression that was not accompanied by adverse cardiac remodeling.

Biomarkers of cardiovascular damage

Acute coronary syndromes (ACS) are due to the rupture or erosion of atheromatous plaques. This produces, depending on plaque size, vascular anatomy and degree of collateral circulation, progressive tissue ischaemia which may progress to cardiomyocyte necrosis. This may then result in cardiac remodelling. Serum biomarkers are available which can be used for diagnosis of all of these stages. Markers to detect myocardial ischaemia at the pre-infarction stage are potentially the most interesting but also the most challenging. An ischaemia marker offers the opportunity to intervene to prevent progression to infarction. The problems with potential ischaemia markers are specificity and the reference diagnostic standard against which they can be judged. To date, only one, ischaemia-modified albumin(R), has reached the point where clinical studies can be performed. The measurement of the cardiac troponins, cardiac troponin T and cardiac troponin I, have become recognised as the diagnostic reference standard for myocardial necrosis. The sensitive nature of these tests has also revealed that myocardial necrosis is also found in a range of other clinical situations, highlighting the need to use all clinical information for diagnosis of acute myocardial infarction. The measurement of B-type natriuretic peptides can be shown to be diagnostic and prognostic in both ACS and detecting the sequelae of post-infarction myocardial insufficiency. The role of the B-type natriuretic peptides in detection of cardiac failure, both acute and chronic, is well defined but remains the subject of further studies, in ACS.

The diagnostic and prognostic value of brain natriuretic peptides in adults with a systemic morphologically right ventricle or Fontan-type circulation

BACKGROUND

In acquired heart disease, brain natriuretic peptide (BNP) and N-Terminal pro-brain natriuretic peptide (NT-proBNP) are increasingly used as diagnostic and prognostic markers. In adult congenital heart disease, the abnormal anatomy and physiology complicate assessment of cardiac function. We studied the clinical correlates of measurement of natriuretic peptides (NP) in adults with a right ventricle in the systemic position or with Fontan-type physiology.

METHODS

A prospective longitudinal study (follow up time 23+/-13 months, mean+/-S.D.) was conducted in a specialised centre on 61 patients (age 26+/-8 years; NYHA class 1.5+/-0.6) including Senning/Mustard corrected transposition, congenitally corrected transposition and Fontan/total cavopulmonary connection. Plasma NP concentration was compared with NYHA class, exercise capacity and echocardiographically determined systemic systolic ventricular function.

RESULTS

Neurohormone concentrations were generally elevated (mean=290% of upper reference limit) and related to NYHA class (P<0.001, NYHA I vs. II-IV). No clinically significant relationship to ventricular function or exercise capacity was found however. An NP measurement could not predict the future course of the disease in terms of functional status or ventricular function.

CONCLUSION

In contrast to patients with acquired heart disease, measurement of NP seems to have low clinical value in adults with a right ventricle in the systemic position or with Fontan-type physiology.

Release of Brain Natriuretic-Related Peptides (BNP, NT-proBNP) and Cardiac Troponins (cTnT, cTnI) in On-pump and Off-pump Coronary Artery Bypass Surgery

BACKGROUND

We studied the kinetic release of cardiac troponins (cTnI and cTnT) and B-type natriuretic peptides (BNP and NT-proBNP) in patients undergoing off-pump or on-pump coronary artery bypass surgery.

METHODS

Twenty-five consecutive patients were prospectively enrolled. The patients were divided into three groups: beating heart (I), and cardiopulmonary bypass (CPB) with warm (II) or cold cardioplegia (III). Plasma samples were obtained before anesthesia induction until the sixth day after surgery.

RESULTS AND CONCLUSIONS

The data were analyzed first for off-pump versus the CPB procedures and second for warm versus cold cardioplegia. The plasma troponin releases appeared to be significantly higher in the CPB groups in comparison to the beating heart group (P < 0.001 and P < 0.002 for cTnI and cTnT peak values, respectively). The peak of the B-type natriuretic peptide release appeared to be more delayed in the groups undergoing CPB than in the beating heart group (day 6 versus days 2 and 4 for NT-proBNP and BNP, respectively). Taken together, our results indicated that the new generation of cTnT assays seemed to be more sensitive than the cTnI assays for the diagnosis of myocardium injury. A lower increase in the cTnT values in the warm cardioplegic group indicated less damage of the myocardium than with cold cardioplegia. Our data also confirm better preservation of the myocardium with off-pump cardiac surgery than with CPB.

NT-proBNP AND BNP VALUES IN CARDIAC PATIENTS WITH DIFFERENT DEGREE OF LEFT VENTRICULAR SYSTOLIC DYSFUNCTION

We investigated the performance of brain natriuretic peptides (BNP and NT-proBNP) in detecting various degrees of left ventricular systolic dysfunction. The NT-proBNP assay (Roche) and the BNP assay (Bayer Shionoria) were performed in 46 patients (mean age 50 years; range 20-79 years) with various types of heart disease (chronic heart failure due to coronary artery disease, cardiomyopathy, acquired valve disease, congenital heart diseases) and different impairment of left ventricular systolic dysfunction was assessed by echocardiography. Patients were divided into four groups according to the left ventricular ejection fraction (LVEF) correlated with clinical severity. Significant differences in medians of NT-proBNP and BNP values between all groups were determined (P= 0.0161 for NT-proBNP and P=0.0180 for BNP). For identifying patients with severe systolic dysfunction (LVEF<40%), receiver operating characteristic (ROC) analysis for both BNP and NT-proBNP was performed. The diagnostic performances expressed as areas under the curve were of 0.69 for NT-proBNP (cut off value 367 pg/ml) and 0.60 for BNP (cut off value 172 pg/ml). However, the BNP showed higher sensitivity (85 % vs. 63 %) and a higher positive predictive value (69 % vs 55 %) than the NT-proBNP. The negative predictive values of BNP and NT-proBNP were similar (70 % and 71 % respectively). Brain natriuretic peptides are promising markers for the diagnosis of severe left ventricular systolic dysfunction.

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.

Contemporary Issues in the Pharmacologic Management of Acute Heart Failure

Acute heart failure is an evolving syndrome that continues to be defined by ongoing studies and registries. It is associated with significant morbidity and mortality and places a huge economic burden on health care systems. Improved understanding of the underlying pathophysiologic processes has prompted interest into understanding the implications of current and future pharmacologic management strategies beyond hemodynamics. Diuretics, vasodilators, and inotropes remain the mainstays of therapy with several new classes of agents on the horizon. Clinicians should understand the rationale for use and limitations of each therapy to maximize benefit and cost-effectiveness, while minimizing the potential for adverse outcomes.

B-type natriuretic peptide and amino terminal proBNP predict one-year mortality in short of breath patients independently of the baseline diagnosis of acute destabilized heart failure

BACKGROUND

The aim of the present study was to demonstrate the capability of B-type natriuretic peptide (BNP) and amino terminal proBNP (NT-proBNP) as prognostic markers in patients with dyspnoea as a chief complaint.

METHODS

BNP and NT-proBNP plasma concentrations were obtained from 251 short of breath patients presenting to the emergency department of a tertiary care hospital. Patients with acute coronary syndromes or trauma were excluded. The endpoint was defined as all-cause mortality, and the study participants were followed up for 365 days from the time they attended the emergency department.

RESULTS

Of the 251 patients, 62 died and 189 stayed alive during follow-up. In the present study, optimal cut off levels for the prediction of survival were 454 ng/L for BNP, and 2060 ng/L for NT-proBNP. Mortality was higher in patients with baseline BNP and NT-proBNP concentrations above these cut off levels (log rank p<0.001; hazard ratios, 0.325 and 0.357, respectively). In multivariate Cox proportional-hazards regression analyses, elevated BNP/NT-proBNP, low systolic blood pressure, and renal dysfunction were predictors of mortality even when the baseline diagnosis of acute destabilized heart failure was factored into the model.

CONCLUSIONS

Both BNP and NT-proBNP measures obtained from short of breath patients presenting to an emergency department may be predictive of one-year all-cause mortality independently of the baseline diagnosis of acute destabilized heart failure.

Brain natriuretic peptide in hemodynamically stable acute pulmonary embolism

BACKGROUND

Controversy exists about the indication of thrombolytic therapy in the subgroup of hemodynamically stable patients with acute pulmonary embolism (PE) and right ventricular dysfunction. Brain natriuretic peptide (BNP) is excreted from the cardiac ventricles in response to cardiomyocyte stretch and can be measured with an easy-to-perform blood test.

OBJECTIVE

The objective of this study was to determine the predictive value of elevated BNP levels for early recurrent venous thromboembolism with or without fatal outcome in hemodynamically stable patients with acute PE. In addition, we assessed the potential clinical consequences of initiating thrombolytic therapy based on the BNP levels alone.

METHODS

A nested case-control study was performed within the framework of a large randomized-controlled trial totalling 2213 hemodynamically stable patients with confirmed acute, symptomatic PE. Ninety patients experienced a fatal or non-fatal recurrent venous thromboembolism during the first 3 months of follow-up (cases); Two hundred and ninety-seven patients with uneventful follow-up served as controls. Blood for BNP levels was obtained at referral and assayed in a central laboratory.

RESULTS

Cases had significantly higher mean baseline BNP levels (P = 0.0002). The odds ratio (OR) for every logarithmic (log) unit increase in BNP concentration was 2.4 (95% CI: 1.5-3.7). A BNP cut-off level of 1.25 pmol L(-1) [the optimal point on the receiver-operating characteristic (ROC) curve] was associated with a sensitivity and specificity of 60% and 62%, respectively. In theory, for every patient correctly receiving thrombolytic therapy at this cut-off, 16 patients will receive this therapy unnecessarily.

CONCLUSIONS

Brain natriuretic peptide level at presentation is significantly associated with early (fatal) recurrent venous thromboembolism in hemodynamically stable patients with acute PE. However, this relationship appears clinically insufficient to guide the initiation of thrombolytic therapy.

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.

Comparative sensitivities between different plasma B-type natriuretic peptide assays in patients with minimally symptomatic heart failure

Plasma B-type natriuretic peptide (BNP) assays have become widely used to diagnose and manage patients with heart failure. However, differences in assay characteristics may have important implications when BNP is used as a screening test for heart failure at a specific cutoff value. We performed a prospective comparison of 2 commercially available assays--one that is a laboratory-based, microparticle enzyme immunoassay (MEIA) that uses EDTA plasma specimens and one that is a point-of-care (POC), single-use fluorescence immunoassay that uses EDTA--anticoagulated whole blood or plasma specimens-in patients with heart failure and healthy controls. Despite the overall concordance between different SNP assays for the diagnosis of heart failure, their sensitivities may differ when compared at the approved diagnostic cutoff value of 100 pg/mL. At this cutoff value, the MEIA on AxSYM demonstrated greater sensitivity than POC Triage BNP assay in minimally symptomatic patients with heart failure. Therefore, for screening purposes, cutoff values for plasma BNP or N-terminal pro-BNP levels should be specific for each assay to optimize test performance. These findings suggest that there is a relationship between the decision statistics used in screening for left ventricular dysfunction and the type of diagnostic assay used.