N-Terminal Pro–B-Type Natriuretic Peptide Testing Improves the Management of Patients With Suspected Acute Heart Failure

Usefulness of N-terminal pro-brain natriuretic peptide and C-reactive protein to predict ICU mortality in unselected medical ICU patients: a prospective, observational study

INTRODUCTION

The performance of N-terminal pro-brain natriuretic peptide (NT-proBNP) and C-reactive protein (CRP) to predict clinical outcomes in ICU patients is unimpressive. We aimed to assess the prognostic value of NT-proBNP, CRP or the combination of both in unselected medical ICU patients.

METHODS

A total of 576 consecutive patients were screened for eligibility and followed up during the ICU stay. We collected each patient's baseline characteristics including the Acute Physiology and Chronic Health Evaluation II (APACHE-II) score, NT-proBNP and CRP levels. The primary outcome was ICU mortality. Potential predictors were analyzed for possible association with outcomes. We also evaluated the ability of NT-proBNP and CRP additive to APACHE-II score to predict ICU mortality by calculation of C-index, net reclassification improvement (NRI) and integrated discrimination improvement (IDI) indices.

RESULTS

Multiple regression revealed that CRP, NT-proBNP, APACHE-II score and fasting plasma glucose independently predicted ICU mortality (all P < 0.01). The C-index with respect to prediction of ICU mortality of APACHE II score (0.82 ± 0.02; P < 0.01) was greater than that of NT-proBNP (0.71 ± 0.03; P < 0.01) or CRP (0.65 ± 0.03; P < 0.01) (all P < 0.01). As compared with APACHE-II score (0.82 ± 0.02; P < 0.01), combination of CRP (0.83 ± 0.02; P < 0.01) or NT-proBNP (0.83 ± 0.02; P < 0.01) or both (0.84 ± 0.02; P < 0.01) with APACHE-II score did not significantly increase C-index for predicting ICU mortality (all P > 0.05). However, addition of NT-proBNP to APACHE-II score gave IDI of 6.6% (P = 0.003) and NRI of 16.6% (P = 0.007), addition of CRP to APACHE-II score provided IDI of 5.6% (P = 0.026) and NRI of 12.1% (P = 0.023), and addition of both markers to APACHE-II score yielded IDI of 7.5% (P = 0.002) and NRI of 17.9% (P = 0.002). In the cardiac subgroup (N = 213), NT-proBNP but not CRP independently predicted ICU mortality and addition of NT-proBNP to APACHE-II score obviously increased predictive ability (IDI = 10.2%, P = 0.018; NRI = 18.5%, P = 0.028). In the non-cardiac group (N = 363), CRP rather than NT-proBNP was an independent predictor of ICU mortality.

CONCLUSIONS

In unselected medical ICU patients, NT-proBNP and CRP can serve as independent predictors of ICU mortality and addition of NT-proBNP or CRP or both to APACHE-II score significantly improves the ability to predict ICU mortality. NT-proBNP appears to be useful for predicting ICU outcomes in cardiac patients.

Biomarkers of risk stratification in congestive heart failure: North American view

There is broad adoption of various cardiac and noncardiac biomarkers in clinical practices across North America for the diagnosis and management of heart failure. Like any clinical condition, there are several overall objectives in biomarker testing: to establish or refute a diagnosis of heart failure and/or cardiac dysfunction; to understand the underlying pathophysiologic processes that may warrant specific interventions; to determine the level of disease severity in a manner to triage medical decisions; to detect and potentially avoid adverse consequences as a result of therapeutic interventions; and to monitor responses to treatment. While at present no single biomarker can serve all of these objectives, the growing experience with cardiac-specific biomarkers, such as natriuretic peptide and cardiac troponin testing, has allowed clinicians to better identify those at heightened short- or long-term risk. It is clear that difficulty remains in translating research evidence into clinical practice. While studies demonstrate statistical differences in short- and long-term outcomes, there is still limited information on how such improvements can be achieved solely based on current therapeutic options. Meanwhile, many commonly ordered tests have important prognostic information that can be overlooked, yet their changes may or may not affect prognosis. With healthcare cost on the rise in North America, clinical utility of biomarkers must demonstrate relative safety and potential incremental benefits to standard approaches.

Natriuretic peptides and their evolving clinical applications

Natriuretic peptides (NP) are quantitative plasma biomarkers of heart failure, which are widely used in clinical practice in many countries. NP levels are accurate in the diagnosis of heart failure in patients presenting with dyspnea. The use of NP improves patient management and reduces total treatment costs in patients with dyspnea. As NP levels quantify disease severity in patients with established heart failure, NP levels are powerful predictors of outcome in predicting death and rehospitalization. NP-guided therapy may improve morbidity in patients with chronic heart failure. Although NP levels also risk-stratify patients with many other conditions such as stable or unstable coronary artery disease, pulmonary embolism and community-acquired pneumonia, there is insufficient evidence on how patient outcome could be altered in patients identified as high risk.

The utility of biomarkers in sorting out the complex patient

Today's patients present with a complexity of illness far more significant than ever before. Risk factors, in particular for cardiovascular, renal, and metabolic diseases, often interact with each other at core pathophysiological levels. Biomarkers are inexpensive tools that may help differentiate disease states in complex patients. Ideal biomarkers are both sensitive and specific to the disease state being examined. Natriuretic peptides are the prototype of ideal biomarkers and are adjuncts for the diagnosis and exclusion of heart failure in the dyspneic patient, especially those presenting with comorbidities such as lung disease. Just as natriuretic peptide levels can be considered the arbiter of congestive heart failure, cardiac troponins are decisive for myocardial necrosis. Novel assays with higher sensitivity will aid in earlier diagnosis, albeit with some decreased specificity. Nevertheless, the patient presenting with comorbidities and atypical symptoms of myocardial infarction will not be arbitrarily sent home. In the future, other novel biomarkers, such as neutrophil gelatinase-associated lipocalin for acute kidney injury, may come to the forefront for diagnosis of disease in the complex patient.

Interpretation and use of natriuretic peptides in non-congestive heart failure settings

Natriuretic peptides (NPs) have been found to be useful markers in differentiating acute dyspneic patients presenting to the emergency department (ED) and emerged as potent prognostic markers for patients with congestive heart failure (CHF). The best-established and widely used clinical application of BNP and NT-proBNP testing is for the emergent diagnosis of CHF in patients presenting with acute dyspnea. Nevertheless, elevated NPs levels can be found in many circumstances involving left ventricular (LV) dysfunction or hypertrophy; right ventricular (RV) dysfunction secondary to pulmonary diseases; cardiac inflammatory or infectious diseases; endocrinology diseases and high output status without decreased LV ejection fraction. Even in the absence of significant clinical evidence of volume overload or LV dysfunction, markedly elevated NP levels can be found in patients with multiple comorbidities with a certain degree of prognostic value. Potential clinical applications of NPs are expanded accompanied by emerging reports regarding screening the presence of secondary cardiac dysfunction; monitoring the therapeutic responses, risk stratifications and providing prognostic values in many settings. Clinicians need to have expanded knowledge regarding the interpretation of elevated NPs levels and potential clinical applications of NPs. Clinicians should recognize that currently the only reasonable application for routine practice is limited to differentiation of acute dyspnea, rule-out-diagnostic-tests, monitoring of therapeutic responses and prognosis of acute or decompensated CHF. The rationales as well the potential applications of NPs in these settings are discussed in this review article.

Natriuretic peptide-guided management of acutely destabilized heart failure: rationale and treatment algorithm

Natriuretic peptides (B-type natriuretic peptide [BNP] and N-terminal pro-B-type natriuretic peptide [NT]-proBNP) have been proven to be strong diagnostic and prognostic tools in the assessment of acutely decompensated heart failure. The emergence of BNP/NT-proBNP testing as a standard of care in this setting has helped to reduce healthcare costs, and may decrease adverse clinical outcomes. The use of BNP and NT-proBNP to "guide" treatment of acutely destabilized heart failure has recently grown. We present an overview of the value of BNP/NT-proBNP in the context of acute heart failure management and therapy optimization, and present an algorithm for natriuretic peptide-guided treatment of acutely destabilized heart failure.

Assessment of serum N-terminal pro-B-type natriuretic peptide concentration for differentiation of congestive heart failure from primary respiratory tract disease as the cause of respiratory signs in dogs

OBJECTIVE

To determine whether serum N-terminal pro-B-type natriuretic peptide (NT-proBNP) concentration is useful in discriminating between cardiac and noncardiac (ie, primary respiratory tract disease) causes of respiratory signs (ie, coughing, stertor, stridor, excessive panting, increased respiratory effort, tachypnea, or overt respiratory distress) in dogs.

DESIGN

Multicenter cross-sectional study.

ANIMALS

P 115 dogs with respiratory signs.

PROCEDURES

Dogs with respiratory signs were solicited for study. Physical examination, thoracic radiography, and echocardiography were used to determine whether respiratory signs were the result of cardiac (ie, congestive heart failure) or noncardiac (ie, primary respiratory tract disease) causes. Serum samples for NT-proBNP assay were obtained at time of admission for each dog. Receiver-operating characteristic curves were constructed to determine the ability of serum NT-proBNP concentration to discriminate between cardiac and noncardiac causes of respiratory signs.

RESULTS

Serum NT-proBNP concentration was significantly higher in dogs with cardiac versus noncardiac causes of respiratory signs. In dogs with primary respiratory tract disease, serum NT-proBNP concentration was significantly higher in those with concurrent pulmonary hypertension than in those without. A serum NT-proBNP cutoff concentration > 1,158 pmol/L discriminated between dogs with congestive heart failure and dogs with primary respiratory tract disease with a sensitivity of 85.5% and a specificity of 81.3%.

CONCLUSIONS AND CLINICAL RELEVANCE

Measuring serum NT-proBNP concentration in dogs with respiratory signs helps to differentiate between congestive heart failure and primary respiratory tract disease as an underlying cause.

Comparison of midregional pro-atrial natriuretic peptide with N-terminal pro-B-type natriuretic peptide in the diagnosis of heart failure

OBJECTIVES

The concentration of atrial natriuretic peptide (ANP) in the circulation is approximately 10- to 50- fold higher than B-type natriuretic peptide (BNP). We sought to compare the accuracy of midregional pro-atrial natriuretic peptide (MRproANP) measured with a novel sandwich immunoassay with N-terminal pro-B-type natriuretic peptide (NTproBNP) in the diagnosis of heart failure.

DESIGN

The diagnosis of heart failure was adjudicated by two independent cardiologists using all available clinical data (including BNP levels) in 287 consecutive patients presenting with dyspnoea to the emergency department (ED). MRproANP and NTproBNP levels were determined at presentation in a blinded fashion.

RESULTS

Heart failure was the adjudicated final diagnosis in 154 patients (54%). Median MRproANP was significantly higher in patients with heart failure as compared to patients with other causes of dyspnoea (400 vs. 92 pmol L(-1), P < 0.001). The diagnostic accuracy of MRproANP was very high with an area under the receiver operating characteristic curve of 0.92 and was comparable with that of NTproBNP (0.92, P = 0.791). Moreover, MRproANP provided incremental diagnostic information to BNP and NTproBNP in patients presenting with BNP levels in the grey zone between 100 and 500 pg mL(-1).

CONCLUSION

Midregional pro-atrial natriuretic peptide is as accurate in the diagnosis of heart failure as NTproBNP. MRproANP seems to provide incremental information on top of BNP or NT-proBNP in some subgroups and should be further investigated in other studies.

Utility of B-natriuretic peptide in the evaluation of left ventricular diastolic function and diastolic heart failure

PURPOSE OF REVIEW

Heart failure with preserved ejection fraction or diastolic heart failure is an increasingly prevalent disease process today. Natriuretic peptides have been shown to provide diagnostic and prognostic utility in patients with systolic heart failure. Here we review current publications exploring the relationship between B-natriuretic peptide (BNP) and diastolic dysfunction.

RECENT FINDINGS

Investigators have found significant correlations between echocardiographic parameters for diastolic dysfunction and serum BNP levels in diagnosing diastolic heart failure. This relationship is linear with respect to severity of left ventricular dysfunction. Newer echocardiographic modalities like tissue Doppler imaging provide measures of elevated left ventricular filling pressures, which are associated with higher plasma BNP levels. Admission and predischarge BNP levels in patients with decompensated diastolic heart failure have been prognostic with respect to in-hospital mortality, short-term mortality, and hospital readmission.

SUMMARY

Review of current literature shows that BNP can be useful in providing diagnostic and prognostic data in patients with symptomatic and asymptomatic diastolic dysfunction. These data, combined with other values such as echocardiographic indices and cardiovascular risk factors, can augment the sensitivity and specificity of BNP.

[NT-proBNP in practice: from chemistry to medicine]

Since the introduction of routine assay for natriuretic peptides, there are a growing number of clinical applications for those new tests. Numerous studies have defined analytical characteristics and clinical interest of NT-proBNP assay. Originally limited to acute heart failure diagnosis in the emergency room, NT-proBNP assay has now a wide number of applications. This literature review presents the "state of art" of this marker, detailing NT-proBNP physiological recent knowledge and its recognized or investigated clinical applications.

The additive value of N-terminal pro-B-type natriuretic peptide testing at the emergency department in patients with acute dyspnoea

BACKGROUND

B-type natriuretic peptide (BNP) and its inactive counterpart NT-proBNP can help to identify or rule out heart failure in patients presenting with acute dyspnoea. It is not well known whether measurement of these peptides can be omitted in certain patient groups.

METHODS

We conducted a prospective observational study of 221 patients presenting with acute dyspnoea at the emergency department. The attending physicians estimated the probability of heart failure by clinical judgement. NT-proBNP was measured, but not reported. An independent panel made a final diagnosis of all available data including NT-proBNP level and judged whether and how NT-proBNP would have altered patient management.

RESULTS

NT-proBNP levels were highest in patients with heart failure, alone or in combination with pulmonary failure. Additive value of NT-proBNP was present in 40 of 221 (18%) of the patients, and it mostly indicated that a more intensive treatment for heart failure would have been needed. Clinical judgement was an independent predictor of additive value of NT-proBNP with a maximum at a clinical probability of heart failure of 36%.

CONCLUSION

NT-proBNP measurement has additive value in a substantial number of patients presenting with acute dyspnoea, but can possibly be omitted in patients with a clinical probability of heart failure of >70%.

Canadian Cardiovascular Society Consensus Conference guidelines on heart failure, update 2009: diagnosis and management of right-sided heart failure, myocarditis, device therapy and recent important clinical trials

The Canadian Cardiovascular Society published a comprehensive set of recommendations on the diagnosis and management of heart failure in January 2006. Based on feedback obtained through a national program of heart failure workshops and through active solicitation of stakeholders, several topics were identified because of their importance to the practicing clinician. Topics chosen for the present update include best practices for the diagnosis and management of right-sided heart failure, myocarditis and device therapy, and a review of recent important or landmark clinical trials. These recommendations were developed using the structured approach for the review and assessment of evidence adopted and previously described by the Society. The present update has been written from a clinical perspective to provide a user-friendly and practical approach. Specific clinical questions that are addressed include: What is right-sided heart failure and how should one approach the diagnostic work-up? What other clinical entities may masquerade as this nebulous condition and how can we tell them apart? When should we be concerned about the presence of myocarditis and how quickly should patients with this condition be referred to an experienced centre? Among the myriad of recently published landmark clinical trials, which ones will impact our standards of clinical care? The goals are to aid physicians and other health care providers to optimally treat heart failure patients, resulting in a measurable impact on patient health and clinical outcomes in Canada.

B type natriuretic peptide--a diagnostic breakthrough in peri-operative cardiac risk assessment?

The B-type natriuretic peptides; B-type natriuretic peptide and N-terminal pro-B-type natriuretic peptide, are increasing being used as biomarkers for the diagnosis, management and prognostication of cardiac failure, but their application in the peri-operative period is unclear. This review examines the current understanding of the role of B-type natriuretic peptides in both the operative and non-operative settings. Normal values, diagnostic thresholds, monitoring targets and significant prognostic levels are identified. Using this as a background, the role of B-type natriuretic peptides in the prediction of peri-operative mortality and morbidity is examined and potential confounders, such as renal failure and body mass index, which may impact significantly on the utility of the biomarkers, are discussed. Clinical recommendations with regard to its use are made and a research agenda is proposed for future peri-operative studies.

Acute decompensated heart failure

Acute decompensated heart failure is the most common cause of hospitalization for patients older than 65 years of age. Although treatment of this condition has improved over the past two decades, the specific approach to patients in the acute setting has not evolved in the same way. A patient facing acute decompensation is experiencing a serious medical condition that is associated with a poor prognosis. In addition, acute decompensated heart failure results in significant costs to the health care system. Significant morbidity and mortality are associated with patients who are readmitted within a year of the first hospitalization. Because of this important problem, further research on improving the prognosis for this condition is warranted. The present article will focus on the risk factors associated with acute decompensation and the importance of this condition, both on prognosis and economics.

Differential diagnosis of acute dyspnea: the value of B natriuretic peptides in the emergency department

Congestive heart failure (CHF) is the main cause of acute dyspnea in patients presenting to an emergency department (ED) and is associated with high morbidity and mortality. B-type natriuretic peptide (BNP) is a polypeptide, released by ventricular myocytes in direct proportion to wall tension, which lowers renin-angiotensin-aldosterone activation. For the diagnosis of CHF, both BNP and the biologically inactive NT-proBNP have similar accuracy. Threshold values are higher in an elderly population, and in patients with renal dysfunction. They might also have a prognostic value. Studies have demonstrated that the use of BNP or NT-proBNP in dyspneic patients early following admission to the ED, reduced the time to discharge and total treatment cost. BNP and NT-proBNP should be available in every ED 24 h a day, because the literature strongly suggests the beneficial impact of an early appropriate diagnosis and treatment in dyspneic patients. The purpose of this review is to indicate recent developments in biomarkers of heart failure and to evaluate their impact on clinical use in the emergency setting.

State of the art: using natriuretic peptide levels in clinical practice

Natriuretic peptide (NP) levels (B-type natriuretic peptide (BNP) and N-terminal proBNP) are now widely used in clinical practice and cardiovascular research throughout the world and have been incorporated into most national and international cardiovascular guidelines for heart failure. The role of NP levels in state-of-the-art clinical practice is evolving rapidly. This paper reviews and highlights ten key messages to clinicians: 1) NP levels are quantitative plasma biomarkers of heart failure (HF). 2) NP levels are accurate in the diagnosis of HF. 3) NP levels may help risk stratify emergency department (ED) patients with regard to the need for hospital admission or direct ED discharge. 4) NP levels help improve patient management and reduce total treatment costs in patients with acute dyspnoea. 5) NP levels at the time of admission are powerful predictors of outcome in predicting death and re-hospitalisation in HF patients. 6) NP levels at discharge aid in risk stratification of the HF patient. 7) NP-guided therapy may improve morbidity and/or mortality in chronic HF. 8) The combination of NP levels together with symptoms, signs and weight gain assists in the assessment of clinical decompensation in HF. 9) NP levels can accelerate accurate diagnosis of heart failure presenting in primary care. 10) NP levels may be helpful to screen for asymptomatic left ventricular dysfunction in high-risk patients.

The use of B-type natriuretic peptide in the management of patients with atrial fibrillation and dyspnea

The utility of B-type natriuretic peptide (BNP) testing in patients with atrial fibrillation (AF) is poorly defined. We analyzed patients (n=452) included in the BNP for Acute Shortness of Breath Evaluation (BASEL) study. Patients were randomly assigned to a diagnostic strategy with or without the use of BNP. Ninety-nine patients presented with AF (n=48 BNP group; n=51 control group). Although comparable with respect to gender and cardiopulmonary comorbidity, patients with AF were older and more often had heart failure as the cause of dyspnea. In addition, patients with AF had higher in-hospital mortality (13% versus 6%, P=0.012). The use of BNP significantly reduced time to discharge (BNP group median 8 days [1-16] versus 12 days [IQR 4-21] control group; P=0.046) in patients with AF. Initial total treatment costs (median) were $4239 [769-7422] in the BNP group and $5940 [4024-10848] in the control group (P=0.041). These benefits were maintained after 90 days: patients in the BNP group had spent fewer days in hospital (10 days [2-21] versus 15 days [IQR 9-27]; P=0.022) and induced lower total treatment costs ($4790 [1260-9387] versus $7179 [4311-13173]; P=0.016). In conclusion, the use of BNP seems to improve the management of patients with AF presenting with dyspnea.

N-terminal pro-brain natriuretic peptide testing in the emergency department: beneficial effects on hospitalization, costs, and outcome

BACKGROUND

N-terminal pro-brain natriuretic peptide (NT-proBNP) is an established biomarker for heart failure. Assessment of this biomarker in patients with acute dyspnea presenting to the emergency department (ED) may aid diagnostic decision-making, resulting in improved patient care and reduced costs.

METHODS

In a prospective clinical trial, patients presenting with acute dyspnea to the ED of the Erasmus Medical College, Rotterdam, the Netherlands, were randomized for either rapid measurement or no measurement of NT-proBNP. For ruling out heart failure, cutoff values of 93 pg/mL in male and 144 pg/mL in female patients were used, and for ruling in heart failure, a cutoff value of 1,017 pg/mL was used. Time to discharge from the hospital and costs related to hospital admission were primary end points. Bootstrap analysis was used for comparison of costs and 30-day mortality between the NT-proBNP and control group.

RESULTS

A total of 477 patients (54% male) was enrolled. The mean age was 59 years, with 44% of patients having a history of cardiac disease. Median time to discharge from the hospital was 1.9 days (interquartile range [IQR], 0.12-8.4 days) in the NT-proBNP group (n = 241) compared with 3.9 days (IQR, 0.16-11.0 days) in the control group (n = 236) (P = .04). Introduction of NT-proBNP testing resulted in a trend toward reduction in costs related to hospital admission and diagnostic investigations of $1,364 per patient (95% CI $-246 to $3,215), whereas 30-day mortality was similar (15 patients in the NT-proBNP and 18 patients in the control group).

CONCLUSIONS

Introduction of NT-proBNP testing for heart failure in the ED setting reduces the time to discharge and is associated with a trend toward cost reduction.

Tolvaptan: the evidence for its therapeutic value in acute heart failure syndrome

INTRODUCTION

Acute heart failure syndrome (AHFS) is one of the leading causes of hospital admission in the US. Tolvaptan is a vasopressin V(2) receptor antagonist that blocks the effect of arginine vasopressin (AVP) in reabsorbing water from the collecting ducts of the nephrons in congestive heart failure.

AIMS

To review the evidence for utilizing tolvaptan in the treatment of AHFS.

EVIDENCE REVIEW

Several clinical trials have sought to assess the clinical effects of tolvaptan in heart failure. Compared with placebo, tolvaptan has been shown to reduce bodyweight and improve serum sodium in patients with AHFS without worsening renal function. Tolvaptan appeared to be well tolerated with a good safety profile. It caused a significant reduction in pulmonary capillary wedge pressure compared with placebo, but has yet to demonstrate reversal of cardiac remodeling. A large-scale mortality trial showed no differences in long-term mortality rates between tolvaptan and placebo, although early symptom relief was apparent with tolvaptan and lower diuretic use.

PLACE IN THERAPY

Tolvaptan has shown to be safe and effective in treating congestion in AHFS. Free water excretion in fluid-overloaded patients vulnerable to cardiorenal compromise with standard diuretic therapy makes V(2) vasopressin receptor blockade an attractive adjunct to standard medical therapy aimed at reducing congestion in AHFS.

Biomarkers in heart failure management

PURPOSE OF REVIEW

Recent literature on the role of biomarkers in heart failure is reviewed, focusing on B-type natriuretic peptide.

RECENT FINDINGS

Knowledge of the processes which increase ventricular stress, thus increasing B-type natriuretic peptide, is key to appropriate utilization and interpretation of B-type natriuretic peptide levels. B-type natriuretic peptide is a useful adjunct to confirm or rule out heart failure. B-type natriuretic peptide is a robust prognostic indicator in all stages of heart failure, with prognostic significance in patients undergoing cardiac and noncardiac surgery, and in those with acute coronary syndromes. Serial B-type natriuretic peptide testing predicts outcomes in hospitalized patients with heart failure. The role of B-type natriuretic peptide in screening high-risk populations is promising, but its use in unselected populations is unclear. There is increasing evidence that the use of B-type natriuretic peptide to guide heart failure management is associated with improved clinical outcomes and reduced health costs.

SUMMARY

Biomarkers play an important role in heart failure, but there remain unanswered questions regarding optimization of their use. They should be used as an adjunct to, not replacement for, clinical assessment. Currently available B-type natriuretic peptide assays have limitations relating to clinical variability and assay specificity. Other neurohormonal, inflammatory and metabolic markers may add complementary information to that provided by currently available B-type natriuretic peptide assays.