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

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.

Useulness of B Natriuretic Peptides and Procalcitonin in Emergency Medicine

Congestive heart failure (CHF) is the main cause of acute dyspnea in patients presented to an emergency department (ED), and it is associated with high morbidity and mortality. B-type natriuretic peptide (BNP) is a polypeptide, released by ventricular myocytes directly proportional to wall tension, for lowering renin-angiotensin-aldosterone activation. For diagnosing CHF, both BNP and the biologically inactive NT-proBNP have similar accuracy. Threshold values are higher in elderly population, and in patients with renal dysfunction. They might have also a prognostic value. Studies demonstrated that the use of BNP or NT-proBNP in dyspneic patients early in the ED reduced the time to discharge, total treatment cost. BNP and NT-proBNP should be available in every ED 24 hours a day, because literature strongly suggests the beneficial impact of an early appropriate diagnosis and treatment in dyspneic patients.

Etiologic diagnosis of febrile patients who present to an ED is complex and sometimes difficult. However, new evidence showed that there are interventions (including early appropriate antibiotics), which could reduce mortality rate in patients with sepsis. For diagnosing sepsis, procalcitonin (PCT) is more accurate than C-reactive protein. Thus, because of its excellent specificity and positive predictive value, an elevated PCT concentration (higher than 0.5 ng/mL) indicates ongoing and potentially severe systemic infection, which needs early antibiotics (e.g. meningitis). In lower respiratory tract infections, CAP or COPD exacerbation, PCT guidance reduced total antibiotic exposure and/or antibiotic treatment duration.

Advances in congestive heart failure management in the intensive care unit: B-type natriuretic peptides in evaluation of acute heart failure

BACKGROUND

Circulating concentrations of B-type natriuretic peptide (BNP) and the aminoterminal fragment (NT-proBNP) of its prohormone (proBNP) are increased in congestive heart failure in proportion to the severity of symptoms, the degree of left ventricular dysfunction, and cardiac filling pressures. Following the introduction of rapid, automated assays for determination of BNP and NT-proBNP, these peptides are increasingly used for diagnostic and prognostic purposes.

OBJECTIVE

To review studies evaluating the diagnostic and prognostic value of BNP and NT-proBNP, with special emphasis on their performance as indicators of acute heart failure in the intensive care unit.

RESULTS

In patients presenting with acute dyspnea, both BNP and NT-proBNP are accurate indicators of acute heart failure and provide prognostic information above and beyond conventional risk markers. Increased plasma levels of BNP and NT-proBNP are not specific for heart failure and may be influenced by a variety of cardiac and noncardiac conditions commonly seen in the intensive care unit, including myocardial ischemia, cardiac arrhythmias, sepsis, shock, anemia, renal failure, hypoxia, acute pulmonary embolism, pulmonary hypertension, and acute respiratory distress syndrome.

CONCLUSIONS

The diagnostic performance of BNP and NT-proBNP as indicators of acute heart failure depends on the clinical setting. In the intensive care unit, particular caution should be used in the interpretation of elevated BNP and NT-proBNP levels.

Amino-terminal pro-B-type natriuretic peptide testing for the diagnosis or exclusion of heart failure in patients with acute symptoms

When used for the evaluation of patients with acute symptoms in the emergency department setting, amino-terminal pro-B-type natriuretic peptide (NT-proBNP) testing is highly sensitive and specific for the diagnosis or exclusion of acute destabilized heart failure (HF), with results comparable to those reported for B-type natriuretic peptide (BNP) testing. When used for the diagnostic evaluation of the patient with possible HF, NT-proBNP testing returns information that may be superior to clinical judgment. However, the optimal application of NT-proBNP is in concert with history and physical examination, adjunctive testing, and with the knowledge of the differential diagnosis of an elevated NT-proBNP level. Studies indicate a dual use for NT-proBNP, both to exclude acute HF (where NT-proBNP concentrations <300 ng/L have a 98% negative predictive value), as well as to identify the diagnosis. To identify acute HF in patients with dyspnea, an age-independent NT-proBNP cut point of 900 ng/L has a similar value as that reported for a BNP value of 100 ng/L. However, age stratification of NT-proBNP using cut points of 450, 900, and 1,800 ng/L (for age groups of <50, 50-75, and >75 years) reduces false-negative findings in younger patients, reduces false-positive findings in older patients, and improves the overall positive predictive value of the marker without a change in overall sensitivity or specificity. Clinically validated, cost-effective algorithms for the use of NT-proBNP testing exist. Therefore, the logical use of NT-proBNP for the evaluation of the patient with suspected acute HF is useful, cost-effective, and may reduce adverse outcomes compared with standard clinical evaluation without natriuretic peptide testing.

Natriuretic peptides

Natriuretic peptides (NPs) are released from the heart in response to pressure and volume overload. B-type natriuretic peptide (BNP) and N-terminal-proBNP have become important diagnostic tools for assessing patients who present acutely with dyspnea. The NP level reflects a compilation of systolic and diastolic function as well as right ventricular and valvular function. Studies suggest that using NPs in the emergency department can reduce the consumption of hospital resources and can lower costs by either eliminating the need for other, more expensive tests or by establishing an alternative diagnosis that does not require hospital stay. Caveats such as body mass index and renal function must be taken into account when analyzing NP levels. Natriuretic peptide levels have important prognostic value in multiple clinical settings, including in patients with stable coronary artery disease and with acute coronary syndromes. In patients with decompensated heart failure due to volume overload, a treatment-induced drop in wedge pressure is often accompanied by a rapid drop in NP levels. Knowing a patient's NP levels might thus assist with hemodynamic assessment and subsequent treatment titration. Monitoring NP levels in the outpatient setting might also improve patient care and outcomes.

The Potential of Cardiac Markers to Improve Patient Management

B-type natriuretic peptide (BNP) is a quantitative marker for heart failure. The use of BNP in patients with dyspnea has consistently shown to improve patient management and reduce treatment cost. Additional indications with the potential to improve patient management include treatment monitoring in acute and chronic heart failure, pulmonary embolism, and coronary artery disease.

B-type natriuretic peptides in heart failure: update on clinical applications and limitations

Heart failure remains an important clinical and public health problem with significant mortality, morbidity and economic consequences. The identification of natriuretic peptides and the large number of investigations that followed have led to a better understanding of the neurohormonal pathophysiology of heart failure. The clinical usefulness of natriuretic peptides in heart failure diagnosis, prognosis and treatment guidance remains to be fully clarified but B-type natriuretic peptides and N-terminal pro-BNP appear to have an emerging role. Like any clinical test, the usefulness of natriuretic peptides measurements depends upon appropriate use and recognition of limitations. This review focuses on these issues.

Heart failure

Heart failure is the most common reason for hospital admission in the United States. All nurses, regardless of their specialty, should be familiar with this clinical syndrome. This column describes the pathophysiology and treatment of heart failure.