[Brain natriuretic peptide in primary care: diagnostic value in heart failure]

To determine the validity and usefulness of brain natriuretic peptide (BNP) for diagnosing left ventricular dysfunction (LVD).

Prospective, descriptive, multi-centred study to validate the diagnostic test.

Primary care centres in the Community of Madrid, Spain.

Consecutive sample of patients at high risk of presenting with LVD.

Data will be gathered from anamnesis, physical examination, ECG, and chest x-ray to find the risk factor(s) for LVD and the presence or absence of symptoms of congestive heart failure according to the Framingham scale. BNP will be determined at PC clinics in all patients who meet the inclusion criteria, using the "triage BNP test." All patients included in the study will be referred to an echocardiography service for an echocardiogram, which will be the gold standard test. Two independent cardiologists will evaluate the echocardiograph without knowing the BNP values.

BNP concentrations will be compared against the kind and degree of LVD. ROC curves analysis will test the capacity of BNP to diagnose LVD. Optimal sensitivity and specificity value will be calculated by means of the position on the curve resulting from the minimum distance at the cut-off point for best sensitivity and specificity. Then, sensitivity, specificity, and positive and negative predictive values will be calculated.

BNP can complement the information provided by other diagnostic tests. It should be included as an important factor in the taking of clinical-therapeutic decisions.