B-Type Natriuretic Peptide—A Paradox in the Diagnosis of Acute Heart Failure with Preserved Ejection Fraction in Obese Patients

Background and objectives: B-type natriuretic peptide (BNP) represents a clinical tool for the diagnosis and prognostic evaluation of acute and chronic heart failure patients. The purpose of this retrospective study was to evaluate BNP values in obese and non-obese patients with acute heart failure with preserved ejection fraction. Materials and methods: In this study, we enrolled 240 patients who presented to the emergency department complaining of acute shortness of breath and fatigue. The patients were divided into two groups according to their body mass index (BMI) values. The BMI was calculated as weight (kilograms) divided by height (square meters). The BNP testing was carried out in the emergency department. Results: Group I included patients with a BMI of <30 kg/m2 and group II included patients with a BMI of ≥30 kg/m2. The average age of the patients was 60.05 ± 5.02 years. The patients in group II were significantly younger compared with those included in group I. Group II included a higher number of women compared to group I. Group I had fewer patients classified within New York Heart Association (NYHA) functional classes III and IV compared with group II. Echocardiography revealed an ejection fraction of ≥50% in all participants. Lower BNP levels were observed in patients from group II (median = 56, IQR = 53–67) in comparison to group I (median = 108.5, IQR = 106–112) (p < 0.001). Conclusions: Obesity and heart failure are continuously rising worldwide. In this retrospective study, we have highlighted the necessity to lower the threshold of BNP levels in obese patients with acute heart failure and preserved ejection fraction.