BNP vs. clinical acumen. (Heart of the Matter).

After more than a decade of study, testing for B-type natriuretic protein has recently been shown to have promise in the diagnosis of congestive heart failure.

But it remains uncertain to what extent measurement of BNP can improve upon clinical judgments.

The concentration of natriuretic proteins increases in heart failure and is closely correlated to increases in a number of neurohormones, including norepinephrine and endothelin. One of three natriuretic proteins, BNP increases in concentration in heart failure as a result of increase in the stretch of the cardiomyocyte. BNP was once referred to as brain natriuretic protein, but it is actually elaborated in the myocardium.

Epidemiologic studies in Europe have shown that the concentration of BNP has a role in identifying patients with early heart failure. Recently Dr. Alan S. Maisel and his associates reported that BNP concentration measured in patients evaluated in the emergency department can distinguish dyspnea occurring as a result of heart failure from that due to primary lung disease and other, undetermined causes (N. Engl. J. Med. 347[3]:161-67, 2002).

The ability to perform the BNP test within 15 minutes at the bedside could provide a unique diagnostic tool to identify cardiac dyspnea and aid in the early diagnosis of heart failure.

The researcher suggested that its availability can speed treatment of heart failure and reduce its morbidity and mortality. Although there was considerable variation in the blood levels obtained in the patients studied, the 83% predictive accuracy for the differentiation of dyspnea secondary to congestive heart failure from dyspnea due to other causes does establish the BNP test as an important aid with a degree of specificity slightly less than that of the PSA test for prostate cancer. Jn addition to its overall accuracy BNP blood level also correlates closely to the degree of heart failure.

How much the BNP level adds to the physician's diagnosis using standard bedside and laboratory data is not dear from the study In presentations ...