Additive diagnostic and prognostic value of Bioelectrical Impedance Vector Analysis (BIVA) to brain natriuretic peptide 'grey-zone' in patients with acute heart failure in the emergency department.

BACKGROUND: Few data are available on diagnostic and prognostic role of quantitative fluid retention evaluated by bioelectrical impedance vector analysis (BIVA) in acute heart failure (AHF) patients at the moment of emergency department presentation. METHODS AND RESULTS: Point vectors and hydration index (HI) by BIVA were obtained in 381 patients referring to an emergency department. For evaluating cardiovascular events, a 30-day follow-up was performed. Patients were divided into AHF (n=270; 70.8%) and no-AHF groups, (n=111; 29.2%). Compared with the no-AHF cohort, the HI value resulted significantly higher in the AHF group (81.2%±6.7 vs. 72.9±3.6%, p<0.001). HI showed a significant diagnostic power for AHF (cut-off 73.4%, area under curve (AUC) 0.87, sensitivity 90%, specificity 54%) and also showed a significant prognostic value both by univariate (odds ratio 1.03 (1-1.07), p =0.025) and multivariate analysis (odds ratio 1.96 (1.05-3.66) p= 0.034) for cardiac events at 30 days. Although in the overall population BIVA did not increase diagnostic accuracy provided by brain natriuretic peptide (BNP), for AHF patients in BNP 'grey values' (100-400 pg/ml) HI showed a significant additive improvement for diagnosis (net reclassification improvement (NRI) 77%) and prognosis (NRI 45%). CONCLUSIONS: While in the overall population BIVA did not increase diagnostic accuracy provided by BNP, in AHF patients a quantitative evaluation of fluid congestion obtained by BIVA at the time of emergency department arrival provides significant additive diagnostic and 30-day prognostic value to BNP, particularly in the BNP 'grey-zone'. This could lead to a better management of these patients with possible improvement in reducing subsequent cardiovascular events.