B-type natriuretic peptide: where are we?

who presented at an A&E department with acute dyspnea and showed that a BNP > 100 pg/mL had a sensitivity of 90% and a specificity of 70% in differentiating dyspnea of cardiac origin from that of other causes. The diagnostic accuracy rose from 74 to 81% when BNP levels were added to clinical criteria7. The diagnostic power of BNP was greater than that of either the Framingham criteria or the National Health and Nutrition Examination Survey (NHANES) criteria, which are two of the most widely used sets of diagnostic criteria for heart failure. The study by Coppola et al.4 does, however, highlight some of the difficulties in using BNP for diagnostic purposes, particularly when concomitant diseases are present. First of all, it is important to remember that the diagnostic cut-off may need to be increased when renal function is impaired, for example from > 100 to > 200 pg/mL in patients with a glomerular filtration rate < 60 mL/min10. Another diagnostically relevant aspect is that BNP, as an expression of wall stress, can also identify patients with heart failure with preserved systolic function. The BNP assay does not, therefore, discriminate patients with systolic dysfunction from those with diastolic dysfunction, although for the same NYHA functional class those with altered systolic function seem to have higher BNP levels8. In their study Coppola et al. highlight that patients at discharge and 30 days postdischarge have significantly lower BNP levels, reflecting the efficacy of treatment. Indeed, one of the developing fields of application of BNP assays is that of patients’ management and optimization of treatment. In a study by Mueller et al.5, 452 patients who presented at the A&E department with acute breathlessness were randomized into two groups. The diagnostic strategy used for one group included a single measurement of BNP, whereas the standard diagnostic strategy – not including BNP assays – was used in the other group. Knowing the BNP level in the A&E department reduced the number of days spent in hospital (8 vs 11 days, p = 0.001), the percentage of admissions (75 vs 85%, p = 0.008), the frequency of admissions to intensive care (15 vs 24%, p = 0.01) and costs (5410 vs 7264 dollars, p = 0.006). S.O.D. Medicina Generale 1 (Responsabile: Dr. Carlo Nozzoli), Azienda Ospedaliero-Universitaria Careggi di Firenze © 2005 CEPI Srl (Ann Ital Med Int 2005; 20: II-III)