Scleroderma

An elevated level of N-terminal pro-brain natriuretic peptide (NT-proBNP) has a high sensitivity and specificity for pulmonary arterial hypertension in patients with systemic sclerosis (SSc-PAH), Australian rheumatologists and cardiologists have suggested.

They investigated a total of 94 patients with systemic sclerosis in four groups: one with SSc-PAH confirmed by right heart catheterisation, another considered at high risk because of findings on trans-thoracic echocardiography, a group with interstitial lung disease, and a group with no cardiopulmonary complications.

“NT-proBNP was highest in the PAH group compared with the other groups, and higher in the risk group compared with controls,” they said.

The marker was positively correlated with systolic and mean pulmonary artery pressure, pulmonary vascular resistance and mean right atrial pressure.

Further analysis defined thresholds for NT-proBNP and/or results on carbon monoxide pulmonary diffusion tests that should prompt investigation for possible PAH, for example with echocardiography, high-resolution CT, 6-minute walk test, and definitive right heart catheterisation when indicated.

PAH accounted for about 30% of deaths related to systemic sclerosis, the researchers said. In its earliest stages, patients were often asymptomatic or minimally symptomatic but early detection and treatment could delay progression and improve survival.

Annual echocardiography was recommended to screen for early PAH, but this strategy had limitations including technical challenges, insufficient reliability in the presence of coexisting lung disease, poor acoustic windows in some patients, the need for expertise, and issues of cost and resource allocation.

NT-proBNP was released by cardiac myocytes in response to increased ventricular wall stress. The blood test was now widely available given its importance in the diagnosis, prognosis and risk stratification of congestive cardiac failure, they said.

Source: James, T. (2012), "BNP screening for pulmonary arterial hypertension in systemic sclerosis"; Rheumatology Update; original article can be viewed here.