Brain natriuretic peptide (BNP) is secreted by the cardiac ventricles in response to pressure and volume overload. The utility of BNP levels in right heart failure, particularly in patients with pulmonary arterial hypertension (PAH), is evolving. Earlier correlations with BNP and hemodynamic parameters in primary pulmonary hypertension (PPH) have indicated the possible use of BNP in clinical practice. Despite increasing data, however, the role of BNP remains undetermined.
185 patients with PAH of varying degrees of severity were studied. These included patients with idiopathic PAH, as well as PAH from secondary causes. Patients with renal insufficiency and left ventricular dysfunction were excluded. BNP levels were analyzed on patients who had recent echocardiograms and/or six-minute walks on the same day of BNP collection. Statistical analyses included linear regression and Spearman rank correlations. Right ventricular (RV) size was correlated with plasma BNP.
In patients with PAH, BNP levels positively correlated to right ventricular systolic pressure (r=0.39, p<0.0001) and negatively correlated to the six-minute walk distance (r=-0.38, p<.0001). These correlations were similar in PPH patients and in PAH patients with secondary causes upon further analyses of the two groups. Treated and untreated patients had similar correlating results, with untreated PPH patients having the highest correlation of BNP and RVSP of all groups (r=0.63, p<0.0001). Furthermore, in patients with BNP levels greater than 5000, 96% had a moderately to severely enlarged RV. With BNP levels <100, 78% had a normal or mildly enlarged RV.
BNP levels appear to increase with elevated RVSP and decrease with six-minute walk distance in patients with PAH. Elevated BNP levels have high specificity for severe RV enlargement, while low levels suggest that the RV is normal or near normal in size.
Plasma BNP levels correlate with hemodynamic and functional parameters, although additional large studies prospectively characterizing the utility of plasma BNP levels in screening, reducing the frequency of invasive testing, and guiding therapy in PAH, appear warranted.
A.K. Gerke, None.