Beta natriuretic peptide (BNP)is a biomarker of intravscular volume and serum levels correlate with left ventricular filling pressures. The relationship between BNP levels and radiographicic findings has not been well studied. Accordingly, the purpose of this study was to determine the relationships between chest radiographic findings and serum BNP levels.
We studied 88 consecutive patients hospitalized with cardiac and/or pulmonary symptoms who had chest xrays and BNP levels determined within 24 hours. Chest radiographs were evaluated for the following findings: left atrial enlargement (LAE), pleural effusions, pulmonary vascular congestion (PVC), cardiothoracic (CT) ratio, and the vascular pedicle width (WPW). Pulmonary vascular congestion was noted to be absent, mild, or greater than mild. The VPW was measure was measured according to previously published methods (Ely).
The duration of time between BNP levels and chest xrays was 80+/-20minutes. There was a direct correlation between serum BNP levels and CT ratio (r=.29,p=0.03). There were no relationships between BNP levels and either VPW (r=-.12, p=.16) or age (r=.10,p=.50). BNP levels were unrelated to the presence of PVC (p=.17),but were higher in patients with LAE (p=.04)and pleural effusions (r=.04). On multivariate analysis analysis, CT ratio was the only independent correlate of BNP levels (r2=.09, p=.02). Log transformation of BNP levels improved the correlation with CT ratio (r=.40, p=.001), but did not alter other univariate or multivariate findings.
In an unselected group of patients hospitalized with cardiac and/or pulmonary symptoms, serum BNP levels are chiefly related to the CT ratio but not to other radigraphic findings.
Although the majority of studies focus on the diagnostic and prognostic value of BNP levels,a direct comparison to standard clinical evaluation is essential in understanding the clinical utility of serum BNP levle determination.
Jason Lazar, None.