Does a patient with a Pro BNP (Pro Brain Natriuretic Peptide) level of less than 36 pg/mL have congestive heart failure (CHF)?

From the Guidelines

A Pro BNP level of less than 36 pg/mL strongly suggests that congestive heart failure (CHF) is unlikely in this patient. Pro BNP is a cardiac biomarker that increases when the heart is under strain, and very low levels like this have a high negative predictive value for ruling out heart failure 1. In clinical practice, different laboratories may use slightly different cutoff values, but generally, a value below 100 pg/mL is considered normal, with values below 50 pg/mL making heart failure particularly unlikely. The extremely low value of 36 pg/mL indicates normal cardiac function from a biomarker perspective.

Key Points to Consider

• The optimum exclusion cut-off point for BNP in non-acute settings is 35 pg/mL, which is very close to the patient's value of 36 pg/mL, suggesting that heart failure is unlikely 1.
• However, diagnosis of CHF should never rely solely on Pro BNP levels.
• A comprehensive clinical assessment including symptoms (shortness of breath, fatigue, edema), physical examination findings, and imaging studies like echocardiography is necessary for definitive diagnosis.
• If the patient has symptoms suggestive of heart failure despite this low Pro BNP, further cardiac evaluation would still be warranted as rare cases of heart failure with normal biomarkers can occur 1.

Clinical Implications

• The patient's low Pro BNP level, in combination with a thorough clinical assessment, can help guide the diagnosis and management of potential heart failure.
• It is essential to consider other cardiac abnormalities that may cause elevated natriuretic peptide levels, such as left ventricular hypertrophy, valvular heart disease, acute or chronic ischemia or hypertension, and pulmonary embolism 1.

From the Research

Pro BNP Level and CHF Diagnosis

• A Pro BNP level of less than 36 pg/mL is considered low, but the provided studies do not specifically mention this exact value as a cutoff for ruling out congestive heart failure (CHF) 2, 3.
• However, a study found that NT-proBNP values <125 pg/mL effectively rule out left ventricular systolic dysfunction (LVSD), which is a common cause of CHF 3.
• Another study suggests that a normal serum BNP (<300 pg/mL) is an important reference standard for excluding CHF, but it does not provide a specific cutoff value for Pro BNP 4.

Diagnostic Performance of Pro BNP

• The diagnostic performance of Pro BNP is influenced by various factors, including age, gender, and left ventricular ejection fraction (LVEF) 3.
• A study found that the application of an age-differentiated cut-off value for NT-proBNP did not increase diagnostic performance 3.
• Pro BNP levels are potentially more useful when a baseline concentration is known for a patient, as BNP levels are proportional to the severity of heart failure 2.

Pro BNP and CHF Prognosis

• Low Pro BNP values are associated with a lower risk of death, independently of age, gender, and LVEF 3.
• A goal to maintain a BNP concentration of less than 100 pg/mL has been shown to correlate with functional improvement in patients with heart failure and has tended to decrease clinical endpoints, such as cardiovascular death 2.