Radioimmunometric assay of natriuretic peptide type-B (BNP) in heart failure

The aim of this study was to assess the value of the radioimmunometric determination of natriuretic peptide type-B (brain natriuretic peptide, BNP) in the diagnosis and prognosis of heart failure, and to study the association between BNP and the clinical, analytical and echocardiographic variables associated with the evolution of heart failure. The study group included 169 patients (74 women and 95 men; mean, 66 years) with heart failure of different causes, admitted consecutively to our hospital. BNP levels were measured with a radioimmunometric assay (Shionora BNP Cis) after day 3 of admission. Patients were also studied by echocardiography. A significant association between the cause of heart failure and the BNP concentration was found (patients with ischaemic disease had the highest BNP values). Systolic function was worse in patients with ischaemic disease or dilated cardiomyopathy. High BNP values were also associated with advanced functional class and male sex. Plasma creatinine correlated positively with plasma BNP. However, we found no significant association with the other clinical variables evaluated. Of the echocardiographic variables analysed, BNP correlated positively with the ventricular diameter and pulmonary artery systolic pressure, and inversely with the shortening fraction; patients with severely impaired systolic function had the highest BNP values. It can be concluded that BNP levels (by radioimmunometric assay) are increased in patients with heart failure, and increase in relation to left ventricular dysfunction and the severity of heart failure. The strong independent association of plasma BNP with the left ventricular ejection fraction, its in vitro stability and the low cost of measurement suggest that plasma BNP assay could become a routine test. BNP assay could be included as an important factor in clinical and therapeutic decision making, as it complements the information provided by other variables used in the diagnosis of heart failure.