Clearing the Congestion: Chest Radiography and BNP to Rule-out Congestive Heart Failure

Purpose: Ruling out congestive heart failure (CHF) is clinically important in Emergency Department (ED) patients. Normal serum brain natriuretic peptide (BNP) represents an important reference standard for excluding CHF. Results of chest radiographs (CXR) are also considered and, when discordant with BNP levels, may result in a clinical dilemma. The present study was designed to elucidate factors associated with CHF on CXR in an ED cohort with normal BNP. Materials and Methods: All adults at our urban health system's EDs who underwent CXR within 24 hours and had a normal BNP (<300 pg/mL) within 24 hours of CXR were retrospectively identified. Of these, 0.9% (8/862) had equivocal CXRs and was excluded. Demographics, comorbidities, CXR report results for CHF, and portable technique were noted. Logistic regression was used to assess factors that are associated with the presence of CHF on CXR. Results: The study cohort comprised 854 patients (433 men, mean age 60.99±15.30) with normal BNP; 91.5% (781/854) had no CHF on CXR and 8.5% (73/854) had CHF. Patients with CHF on CXR had a higher body mass index (32.9 vs. 29.8 kg/m2, P=0.0205) were more likely to have a history of CHF or diabetes with complications (OR: 2.72 and 2.53, respectively), had higher serum BNP levels (median 164 vs. 98 pg/mL, P=4.91×10-5), and underwent portable examination more frequently (86.3% vs. 57.5%, OR: 4.65). Conclusions: Normal serum BNP was concordant with CXR results, adding diagnostic confidence in ruling out CHF in a large majority of ED patients. A higher body mass index, history of CHF, and diabetes with complications and portable CXR technique were associated with CHF on CXR among the minority with normal BNP.