B-type natriuretic peptide (BNP), a neurohormone released from the cardiac ventricles, is widely accepted as a diagnostic marker of congestive heart failure. Relationship between BNP and left ventricular systolic dysfunction (LVSD) remains inconclusive.

Echocardiogram and BNP (Triage(R), pg/ml) were obtained in 332 patients who were admitted in the division of Cardiology of St. Mary's Hospital. Mean and median BNP values, capacity of BNP to differentiate LVSD were assessed using student's t test and receiver-operating-characteristic (ROC) curves.

LVSD and dyspnea independently elevated both mean and median values of BNP. BNP had a fair capacity to differentiate mild LVSD or left ventricular ejection fraction (LVEF)< or =50% (area under the ROC curve 0.76) at cutoff value of 100 pg/ml but an excellent capacity to differentiate moderate to severe LVSD or LVEF > or =35% (area under the ROC curve 0.90) at cutoff value of 180 pg/ml. In patients without LVSD but BNP level greater than 100 pg/ml, tachyarrhythmia, valvular heart disease, myocardial infarction, left ventricular hypertrophy, pulmonary artery hypertension were frequent findings.

BNP is an excellent test in differentiating moderate to severe LVSD or LVEF < or =35 in patients having cardiac diseases or seeking urgent medical care, and in selecting out candidates for echocardiogram.