Cut-off values of B-type natriuretic peptide for the diagnosis of congestive heart failure in patients with dyspnoea visiting emergency departments: a study on Korean patients visiting emergency departments.

OBJECTIVES: To determine the optimal cut-off values of B-type natriuretic peptide (BNP) for the diagnosis of congestive heart failure (CHF) in 1040 Korean patients with dyspnoea visiting emergency departments.
METHODS: BNP values were measured for 662 patients without CHF to examine whether significant relationships existed between the BNP values and age, gender or underlying disease. In 378 patients with CHF, a similar analysis was performed in addition to the examination of the relationship between the mean BNP values and CHF severity.
RESULTS: The optimal threshold for the detection of heart failure was a BNP concentration of 296.5 pg/mL, regardless of age, sex and underlying disease among the Korean study population. In the non-CHF patients, women showed significantly higher mean BNP values than did men. Further, in these patients, the mean BNP values of men with underlying disease (hypertension, angina pectoris, chronic renal failure, chronic obstructive pulmonary disease) and those with at least two underlying diseases, one of which was hypertension, was higher than those without underlying disease, whereas no difference was observed between women with and without underlying disease. Based on the New York Heart Association classification, echocardiography findings and mortality rate of the CHF patients, the BNP value was found to be related to both the severity of heart failure and its prognosis.
CONCLUSIONS: The BNP concentration used for the diagnosis of CHF in Korean people is considerably higher than the normal cut-off value of 100 pg/mL. In the non-CHF patients, the BNP values of women were influenced less by underlying disease. This suggests that the factors that influence BNP values in women are different from those in men.