Heart Failure With Preserved Ejection Fraction and Low B-type Natriuretic Peptide: A Diagnostic Dilemma

Heart failure (HF) is referred to as a clinical syndrome caused by an abnormality in the cardiac function/structure of the heart, leading to pulmonary or systemic vascular congestion. B-type natriuretic peptide (BNP) is particularly useful for ruling out heart failure when levels are low due to its high negative predictive value. On the other hand, BNP has reduced specificity for heart failure with preserved ejection fraction (HFpEF) due to increased clearance and enhanced degradation of natriuretic peptides (NP) which contribute to lower BNP levels. In patients with HFpEF, reduced myocardial wall stress is associated with low BNP, as compared to heart failure with reduced ejection fraction (HFrEF). BNP and N-terminal pro-BNP (NT-proBNP) levels may be in the normal range in chronically treated heart failure patients, especially if younger than 75 years. BNP levels can be lower in HFpEF due to factors like obesity and atrial function. NT-proBNP levels vary by ethnicity, with African American patients exhibiting lower levels, potentially linked to salt-sensitive hypertension and left ventricular hypertrophy. In our case report, the patient presented with classic signs and symptoms of HFpEF exacerbation but had a BNP level that was inconsistent with HF. This signifies the importance of over-reliance on BNP in patients with HFpEF.