B-type natriuretic peptide (BNP) and N-terminal-proBNP for heart failure diagnosis in shock or acute respiratory distress

Electroanalytical point-of-care detection of gold standard and emerging cardiac biomarkers for stratification and monitoring in intensive care medicine - a review

Determination of specific cardiac biomarkers (CBs) during the diagnosis and management of adverse cardiovascular events such as acute myocardial infarction (AMI) has become commonplace in emergency department (ED), cardiology and many other ward settings. Cardiac troponins (cTnT and cTnI) and natriuretic peptides (BNP and NT-pro-BNP) are the preferred biomarkers in clinical practice for the diagnostic workup of AMI, acute coronary syndrome (ACS) and other types of myocardial ischaemia and heart failure (HF), while the roles and possible clinical applications of several other potential biomarkers continue to be evaluated and are the subject of several comprehensive reviews. The requirement for rapid, repeated testing of a small number of CBs in ED and cardiology patients has led to the development of point-of-care (PoC) technology to circumvent the need for remote and lengthy testing procedures in the hospital pathology laboratories. Electroanalytical sensing platforms have the potential to meet these requirements. This review aims firstly to reflect on the potential benefits of rapid CB testing in critically ill patients, a very distinct cohort of patients with deranged baseline levels of CBs. We summarise their source and clinical relevance and are the first to report the required analytical ranges for such technology to be of value in this patient cohort. Secondly, we review the current electrochemical approaches, including its sub-variants such as photoelectrochemical and electrochemiluminescence, for the determination  of important CBs highlighting the various strategies used, namely the use of micro- and nanomaterials, to maximise the sensitivities and selectivities of such approaches. Finally, we consider the challenges that must be overcome to allow for the commercialisation of this technology and transition into intensive care medicine.

A Review of Prognosis Model Associated With Cardiogenic Shock After Acute Myocardial Infarction

Objective: Cardiogenic shock seriously affects the survival rate of patients. However, few prognostic models are concerned with the score of cardiogenic shock, and few clinical studies have validated it. In order to optimize the diagnosis and treatment of myocardial infarction complicated with cardiogenic shock and facilitate the classification of clinical trials, the prognosis score model is urgently needed. Methods: Cardiogenic shock, severe case, prognosis score, myocardial infarction and external verification were used as the search terms to search PubMed, Embase, Web of Science, Cochrane, EBSCO (Medline), Scopus, BMC, NCBI, Oxford Academy, Science Direct, and other databases for pertinent studies published up until 1 August 2021. There are no restrictions on publication status and start date. Filter headlines and abstracts to find articles that may be relevant. The list of references for major studies was reviewed to obtain more references. Results and Conclusions: The existing related models are in urgent need of more external clinical verifications. In the meanwhile, with the development of molecular omics and the clinical need for optimal treatment of CS, it is urgent to establish a prognosis model with higher differentiation and coincidence rates.

Diabetic pregnancy as a novel risk factor for cardiac dysfunction in the offspring-the heart as a target for fetal programming in rats

AIMS/HYPOTHESIS

The impact of diabetic pregnancy has been investigated extensively regarding offspring metabolism; however, little is known about the influence on the heart. We aimed to characterise the effects of a diabetic pregnancy on male adult offspring cardiac health after feeding a high-fat diet in an established transgenic rat model.

METHODS

We applied our rat model for maternal type 2 diabetes characterised by maternal insulin resistance with hyperglycaemia and hyperinsulinaemia. Diabetes was induced preconceptionally via doxycycline-induced knock down of the insulin receptor in transgenic rats. Male wild-type offspring of diabetic and normoglycaemic pregnancies were raised by foster mothers, followed up into adulthood and subgroups were challenged by a high-fat diet. Cardiac phenotype was assessed by innovative speckle tracking echocardiography, circulating factors, immunohistochemistry and gene expression in the heart.

RESULTS

When feeding normal chow, we did not observe differences in cardiac function, gene expression and plasma brain natriuretic peptide between adult diabetic or normoglycaemic offspring. Interestingly, when being fed a high-fat diet, adult offspring of diabetic pregnancy demonstrated decreased global longitudinal (-14.82 ± 0.59 vs -16.60 ± 0.48%) and circumferential strain (-23.40 ± 0.57 vs -26.74 ± 0.34%), increased relative wall thickness (0.53 ± 0.06 vs 0.37 ± 0.02), altered cardiac gene expression, enlarged cardiomyocytes (106.60 ± 4.14 vs 87.94 ± 1.67 μm), an accumulation of immune cells in the heart (10.27 ± 0.30 vs 6.48 ± 0.48 per fov) and higher plasma brain natriuretic peptide levels (0.50 ± 0.12 vs 0.12 ± 0.03 ng/ml) compared with normoglycaemic offspring on a high-fat diet. Blood pressure, urinary albumin, blood glucose and body weight were unaltered between groups on a high-fat diet.

CONCLUSIONS/INTERPRETATION

Diabetic pregnancy in rats induces cardiac dysfunction, left ventricular hypertrophy and altered proinflammatory status in adult offspring only after a high-fat diet. A diabetic pregnancy itself was not sufficient to impair myocardial function and gene expression in male offspring later in life. This suggests that a postnatal high-fat diet is important for the development of cardiac dysfunction in rat offspring after diabetic pregnancy. Our data provide evidence that a diabetic pregnancy is a novel cardiac risk factor that becomes relevant when other challenges, such as a high-fat diet, are present.

Molecular signature of cardiogenic shock

The incidence of cardiogenic shock (CS) has increased remarkably over the past decade and remains a challenging condition with mortality rates of ∼50%. Cardiogenic shock encompasses cardiac contractile dysfunction; however, it is also a multiorgan dysfunction syndrome, often complicated by a systemic inflammatory response with severe cellular and metabolic dysregulations. Here, we review the evidence on the biochemical manifestations of CS, elaborating on current gold standard biomarkers and novel candidates from molecular signatures of CS. Glucose and lactate, both identified over a century ago, remain the only clinically used biomarkers in current predictive risk scores. Novel genomic, transcriptomic, and proteomic data are discussed, and a recently reported molecular score derived from unbiased proteomic discovery, the CS4P, which includes liver fatty acid-binding protein, beta-2-microglobulin, fructose-bisphosphate aldolase B, and SerpinG1 is comprehensively described. Recent advances in -omics technologies provide new insight into a more holistic molecular signature of CS. Thus, we need to open new diagnostic and therapeutic avenues if we aim to improve outcomes.

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The use of echocardiographic indices in defining and assessing right ventricular systolic function in critical care research

PURPOSE

Many echocardiographic indices (or methods) for assessing right ventricular (RV) function are available, but each has its strengths and limitations. In some cases, there might be discordance between the indices. We conducted a systematic review to audit the echocardiographic RV assessments in critical care research to see if a consistent pattern existed. We specifically looked into the kind and number of RV indices used, and how RV dysfunction was defined in each study.

METHODS

Studies conducted in critical care settings and reported echocardiographic RV function indices from 1997 to 2017 were searched systematically from three databases. Non-adult studies, case reports, reviews and secondary studies were excluded. These studies' characteristics and RV indices reported were summarized.

RESULTS

Out of 495 non-duplicated publications found, 81 studies were included in our systematic review. There has been an increasing trend of studying RV function by echocardiography since 2001, and most were conducted in ICU. Thirty-one studies use a single index, mostly TAPSE, to define RV dysfunction; 33 used composite indices and the combinations varied between studies. Seventeen studies did not define RV dysfunction. For those using composite indices, many did not explain their choices.

CONCLUSIONS

TAPSE seemed to be the most popular index in the last 2-3 years. Many studies used combinations of indices but, apart from cor pulmonale, we could not find a consistent pattern of RV assessment and definition of RV dysfunction amongst these studies.

Bedside biomarkers in pediatric cardio renal injuries in emergency

Point of care testing (POCT) using biomarkers in the emergency department reduces turnaround time for clinical decision making. An ideal biomarker should be accurate, reliable and easy to measure with a standard assay, non-invasive, sensitive and specific with defined cutoff values. Conventional biomarkers for renal injuries include rise in serum creatinine and fluid overload. Recently, neutrophil gelatinase associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1), cystatin C, interleukin-18 (IL-18) and liver fatty acid binding protein (L-FABP) have been studied extensively for their role in acute kidney injury associated with various clinical entities. Biochemical markers of ischaemic cardiac damage commonly used are plasma creatine kinase and cardiac troponins (cTn). Clinically valuable cardiac markers for myocardial injury in research at present comprise BNP/NT-proBNP and to a lesser extent, CRP, which are independent predictors of adverse events including death and heart failure. Current status of point of care biomarkers for diagnosis and prognostication of renal and cardiac injuries in pediatric emergency care is appraised in this review.

Does dexmedetomidine provide cardioprotection in coronary artery bypass grafting with cardiopulmonary bypass? A pilot study

OBJECTIVE

The purpose of this pilot study was to evaluate whether dexmedetomidine has a cardioprotective effect during coronary artery bypass graft surgery with cardiopulmonary bypass (CPB).

DESIGN

A prospective, double-blind, randomized controlled trial.

SETTING

A university hospital.

PARTICIPANTS

Thirty-eight patients undergoing coronary artery bypass graft surgery.

INTERVENTIONS

Patients were randomized into 2 groups: dexmedetomidine and placebo groups. In the dexmedetomidine group, dexmedetomidine infusion was started by a loading dose of 0.5 μg/kg/10 min, followed by a continuous infusion of 0.5 μg/kg/h. The placebo group received the same volume of saline. Measurements of central venous pressure, mean pulmonary artery pressure (MPAP) and cardiac index were performed before and after dexmedetomidine loading dose and 2, 24 and 48 hours after CPB. Simultaneously, arterial blood was sampled for CK-MB, cardiac troponin T, and N-terminal probrain natriuretic peptide.

MEASUREMENTS AND MAIN RESULTS

CK-MB, cardiac troponin T and N-terminal probrain natriuretic peptide values were elevated in the periods after CPB in both groups (p<0.05) and there were no statistically significant differences between groups. MPAP was decreased in the dexmedetomidine group at the 2nd, 24th and 48th hour after CPB (p<0.001, p<0.001, p = 0.002, respectively). Higher cardiac index values were seen earlier in the dexmedetomidine group than in the placebo group (p< 0.05).

CONCLUSIONS

Myocardial damage was not reduced by administration of 0.5 μg/kg loading dose and 0.5 μg/kg/h infusion of dexmedetomidine. However MPAP tended to be lower in the dexmedetomidine group. Large-scale clinical outcome studies are indicated to confirm the effect of dexmedetomidine.

Review on natriuretic peptides: where we are, where we are going

BACKGROUND

Tremendous advances have been made in our understanding of the pathophysiology and treatment of congestive heart failure. However, diagnosis of the disease still remains difficult, even with a comprehensive physical examination. Symptoms such as dyspnea are nonspecific and insensitive indicators for heart failure, which can go largely undetected. Several studies have suggested the need for new diagnostic capabilities, especially with the increasing prevalence of heart failure in the US. The discovery of natriuretic peptides as diagnostic biomarkers has been one of the most critical advances for the management of heart failure. Both B-type natriuretic peptide and N-terminal pro-B-type natriuretic peptide have the potential to diagnose heart failure, assess prognostic risk of rehospitalization and mortality, and even help guide treatment. Their relative cost-effectiveness and availability have also facilitated their acceptance into many emergency departments, clinics and in-patient units as standard care when evaluating patients with suspected heart failure. Our understanding of the natriuretic peptide system is still in its infancy, but natriuretic peptides have emerged as important diagnostic and prognostic tools that have generated interest in finding broader applications for their use.

OBJECTIVE

The purpose of this review is to discuss the clinical approaches and future applications of natriuretic peptides in diagnosing and managing treatment of congestive heart failure.

METHOD

A comprehensive review of studies to assess the utility of natriuretic peptides for diagnosis and prognosis of heart failure and other conditions.

CONCLUSION

Natriuretic peptides are powerful tools to aid the physician in the diagnosis, prognosis and management of heart failure in both in-patient and out-patient settings. However, natriuretic peptides should be used as an adjunct test as many circumstances can also influence changes in natriuretic peptide levels.

Cardiac biomarkers in the critically ill

Cardiac biomarkers have well-established roles in acute coronary syndrome and congestive heart failure. In many instances, the detection of cardiac biomarkers may aid in the diagnosis and risk assessment of critically ill patients. Despite increasing interest in the use of cardiac biomarkers in noncardiac critical illness, no clear consensus exists on how and in which settings markers should be measured. This article briefly describes what constitutes an ideal biomarker and focuses on those that have been most well studied in critical illness, specifically troponin, the natriuretic peptides, and heart-type fatty acid-binding protein.

High circulating N-terminal pro-B-type natriuretic peptide is associated with greater systolic cardiac dysfunction and nonresponsiveness to fluids in septic vs nonseptic critically ill patients

PURPOSE

It is still unclear whether circulating levels of N-terminal pro-B-type natriuretic peptide (NT-proBNP) reflect cardiac filling and function in the critically ill patient, particularly during sepsis and a proinflammatory response that may induce NT-proBNP release from the heart.

MATERIALS AND METHODS

We prospectively evaluated the value of NT-proBNP as a marker of cardiac loading, function, and response to fluid loading in 18 septic and 68 nonseptic, critically ill patients in the intensive care unit of a university medical center. Transpulmonary thermal dilution and pressure measurements were done, and plasma NT-proBNP was determined before and after colloid fluid loading.

RESULTS

Compared with nonseptic patients, NT-proBNP plasma levels were higher and systolic cardiac function indices were lower in patients with sepsis than those without sepsis. N-terminal pro-B-type natriuretic peptide best related, from all hemodynamic parameters before and after fluid loading, to systolic cardiac function (rather than diastolic filling) variables, independently of confounders such as renal dysfunction (judged from serum creatinine). In addition, a high NT-proBNP (>3467 pg/mL) predicted absence of fluid responsiveness in sepsis only.

CONCLUSIONS

Our data suggest that an increased circulating NT-proBNP plasma level is an independent marker of greater systolic cardiac dysfunction, irrespective of filling status, and is a better predictor of fluid nonresponsiveness in septic vs nonseptic, critically ill patients.

Use of B-type natriuretic peptide in critically ill patients

B-type natriuretic peptide (BNP) is increasingly used in emergency departments to assess the cause of acute dyspnea and in cardiology to follow treatments and predict outcome. It is increasingly used in the intensive care unit in situations such as respiratory failure (acute pulmonary edema, exacerbation of chronic obstructive pulmonary disease and difficult weaning from ventilator) or when pulmonary embolism is suspected. BNP has also been used to assess alteration of myocardial function in sepsis. Plasma BNP is very high in septic-shock patients (>1000 pg/ml), which is suggested to relate to both myocardial stretch and to an alteration in one of the BNP clearance pathways. Whether BNP at admission or at discharge may predict outcome requires further investigation.

Cardiovascular biomarkers in the ICU

PURPOSE OF REVIEW

Natriuretic peptides are markers of heart failure and/or cardiac dysfunction that provide useful diagnostic and prognostic information in patients with dyspnea and/or respiratory failure in the emergency department. Cardiac troponins (cTn) have markedly simplified the diagnosis of myocardial infarction. In critically ill patients, conditions like coexisting organ dysfunction multiorgan involvement or altered synthesis/clearance may confound interpretation of designated biomarkers, including natriuretic peptides and cTn. This review focuses on recently published articles relating to the use of natriuretic peptides and cTn in critically ill patients.

RECENT FINDINGS

One new study addresses diagnostic utility of B-type natriuretic peptide to distinguish low-pressure pulmonary edema (acute lung injury/acute respiratory distress syndrome) from high-pressure (cardiogenic) pulmonary edema. Other studies highlight the prognostic value of natriuretic peptides either in unselected and general noncardiac ICU patients and reveal an important reason for elevated B-type natriuretic peptide levels in septic shock.Interesting data focusing on diagnostic and prognostic ability of systematic cTn screening measurements in ICU patients became available.

SUMMARY

Recent studies confirm the excellent prognostic value of natriuretic peptide measurements in ICU patients. Diagnostic properties of natriuretic peptide in ICU patients still remain ambiguous and require further evaluation. Systematic screening with cTn reveals more myocardial infarctions and provides important prognostic information.

The use of B-type natriuretic peptide in paediatric patients: a review of literature

OBJECTIVE

Plasma levels of brain natriuretic peptide (BNP) and its inactive fragment N-terminal pro-BNP are recognized as reliable markers of ventricular dysfunction in adults. We aimed to verify BNP applications in children.

METHODS

A review of the literature on this subject was carried out.

RESULTS

When dealing with paediatric patients, age and sex-related normal values must be considered. Higher BNP plasma levels are reported in children with chronic heart failure; they are related with the type of dysfunction and with prognosis. Moreover, increased BNP levels have been reported in asymptomatic children and adolescents pretreated with anthracyclines, who are at risk for ventricular dysfunction.

CONCLUSION

BNP and pro-BNP also seem to be effective markers of ventricular dysfunction in paediatric patients. Clinical use may be extended not only for the characterization of heart dysfunction, but also for monitoring asymptomatic patients at specific risk. To this purpose, wider application in clinical trials appears warranted.

Hyper osmolality does not modulate natriuretic peptide concentration in patients after coronary artery surgery

BACKGROUND

The heart secretes natriuretic peptides (NPs) in response to myocardial stretch. Measuring NP concentrations is a helpful tool in guiding treatment. It has been suggested that sodium ion and hyperosmolality could affect NP excretion. If this is true, peri-operative NP measurements could be inconsistent when hypertonic solutions are used. With different osmolalities but equal volumes of hydroxyethyl starch (HES)--and hypertonic saline (HS)--infusions, this double-blinded study tested the hypothesis that osmolality modulates the excretion of NPs.

METHODS

Fifty coronary surgery patients were randomized to receive within 30 min 4 ml/kg either HS or HES post-operatively. Samples for analysis of atrial NP (ANP), brain NP (BNP), plasma and urine sodium and osmolality and urine oxygen tension were obtained before and 60 min after starting the infusions and on the first post-operative morning. The haemodynamic parameters were measured at the same time points.

RESULTS

Plasma osmolality and sodium increased only in the HS group. Changes in plasma BNP and ANP levels did not differ between the groups (P=0.212 and 0.356). There were no correlations between NP levels and osmolality or sodium at any time point. In the HS group, urine volume was higher (3295 vs. 2644 ml; P<0.05) and the need for furosemide treatment was less (0.4 vs. 3.8 mg; P<0.01) than in the HES group.

CONCLUSIONS

The absence of effects of plasma sodium content or hyperosmolality on NP release validates the value of NPs as a biomarker in peri-operative patients.

What is the value of B-type natriuretic peptide testing for diagnosis, prognosis or monitoring of critically ill adult patients in intensive care?

BACKGROUND

B-natriuretic peptide (BNP) and aminoterminal proBNP (NT-proBNP) are clinically useful for the diagnosis of decompensated heart failure and for prognosis in heart failure and acute coronary syndromes. Clinical use of these biomarkers in critically ill patients being treated in intensive care is not well established.

METHODS

This is a narrative review of evidence identified searching MEDLINE with the strategy [(BNP OR NT-proBNP) AND (critical illness AND intensive care)]. Seven primary reports and two narrative reviews were retrieved. For completeness, literature from each of the following searches was reviewed: [(BNP OR NT-proBNP) AND (critical illness)] and [(BNP OR NT-proBNP) AND (intensive care)].

RESULTS

Primary literature used BNP and NT-proBNP for diagnosis, prognosis and monitoring. For diagnosis of acute lung injury in unselected intensive care patients and for diagnosis of heart failure in trauma patients, the biomarkers had low sensitivity and are of modest use. BNP and NT-proBNP were found to have a significant ability to prognosticate adverse outcomes in critically ill patients. A single paper examined the use of BNP as a non-invasive replacement for pulmonary capillary wedge pressure, finding little value. The impact of renal insufficiency on the markers was noted as a confounder in most studies. In the secondary searches, some preliminary data suggested a possible role for the natriuretic peptides in exclusion of a cardiac cause for certain conditions among intensive care unit (ICU) patients. However, the general findings were that the performance of BNP and NT-proBNP is unimpressive among ICU patients.

CONCLUSIONS

Currently, utilization of BNP and NT-proBNP does not appear to provide much useful information or have a substantial role in the care of critically ill patients in intensive care.

The use of natriuretic peptides in the intensive care unit

PURPOSE OF REVIEW

B-type natriuretic peptides are quantitative markers of heart failure (and/or cardiac stress) that summarize the extent of systolic and diastolic left ventricular dysfunction, valvular dysfunction, and right ventricular dysfunction. Based on the observation that heart failure is common albeit difficult to diagnose in the ICU, several studies have begun to evaluate the potential use of B-type natriuretic peptides in various ICU settings.

RECENT FINDINGS

Previous pilot studies have examined the use of B-type natriuretic peptide in the differential diagnosis of hypoxemic respiratory failure, to differentiate cardiogenic from noncardiogenic shocks or to predict fluid responsiveness, to assess myocardial dysfunction and prognosis in patients with severe sepsis, and to predict ventilatory weaning failure.

SUMMARY

Although previous studies were small, they highlight the potential of using B-type natriuretic peptides as a noninvasive easily available tool to quantify cardiac stress.

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.

Brain natriuretic peptide is a good predictor for outcome in cardiac surgery

BACKGROUND AND AIM

The heart secretes brain natriuretic peptide (BNP) in response to myocardial stretch. The aim of this study was to determine whether adverse effects after cardiac surgery were associated with higher serum BNP levels pre-operatively.

METHODS

One hundred and thirty-five patients undergoing various cardiac procedures were included in the study, and N-terminal pro-BNP (NT-pro-BNP) was measured pre-operatively. Post-operative complications were defined as follows: (i) a post-operative length of stay in the intensive care unit (ICU) exceeding 48 h; (ii) mortality at 28 days; (iii) the need for inotropic agents and/or intra-aortic balloon pump (IABP); and (iv) renal failure. Serum NT-pro-BNP values were compared for patients with and without complications. The serum NT-pro-BNP level was also correlated with the euroSCORE and ejection fraction (EF).

RESULTS

Pre-operative serum NT-pro-BNP levels were significantly higher in patients with an ICU length of stay of more than 2 days or death prior to post-operative day 28 (3118 ng/l vs. 705 ng/l; P < 0.001). Pre-operative serum NT-pro-BNP levels were also significantly higher in patients needing inotropic agents (2628 ng/l vs. 548 ng/l; P < 0.001) or IABP insertion (3705 ng/l vs. 935 ng/l; P = 0.001) or developing renal failure (2857 ng/l vs. 945 ng/l; P < 0.001) post-operatively. The correlation between the serum NT-pro-BNP level and euroSCORE was good (r = 0.658; P < 0.001). The receiver operating characteristic (ROC) curves were used to assess the ability of serum NT-pro-BNP, euroSCORE and EF to predict outcome after cardiac surgery. This revealed an area under the ROC curve for the length of stay in the ICU or mortality at 28 days of 0.829 for serum NT-pro-BNP, 0.814 for euroSCORE and 0.328 for EF assessed by transesophageal echocardiography, indicating that the pre-operative serum NT-pro-BNP level is a good prognostic indicator for outcome after cardiac surgery.

CONCLUSION

Serum NT-pro-BNP is a good predictor for complications after cardiac surgery, and is as good as euroSCORE and better than EF.

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.

Interpretation of B-type natriuretic peptide in cardiac disease and other comorbid conditions

B-Type natriuretic peptide (BNP) is elevated in states of increased ventricular wall stress. BNP is most commonly used to rule out congestive heart failure (CHF) in dyspneic patients. BNP levels are influenced by age, gender and, to a surprisingly large extent, by body mass index (BMI). In addition, it can be elevated in a wide variety of clinical settings with or without CHF. BNP is elevated in other cardiac disease states such as the acute coronary syndromes, diastolic dysfunction, atrial fibrillation (AF), amyloidosis, restrictive cardiomyopathy (RCM), and valvular heart disease. BNP is elevated in non-cardiac diseases such as pulmonary hypertension, chronic obstructive pulmonary disease, pulmonary embolism, and renal failure. BNP is also elevated in the setting of critical illness such as in acute decompensated CHF (ADHF) and sepsis. This variation across clinical settings has significant implications given the increasing frequency with which BNP testing is being performed. It is important for clinicians to understand how to appropriately interpret BNP in light of the comorbidities of individual patients to maximize its clinical utility. We will review the molecular biology and physiology of natriuretic peptides as well as the relevant literature on the utilization of BNP in CHF as well as in other important clinical situations, conditions that are commonly associated with CHF and or dyspnea.