Bioelectrical impedance vector analysis and clinical outcomes in patients with acute heart failure

Fluid overload is a hallmark in acute heart failure (AHF). Bioelectrical impedance vector analysis (BIVA) has emerged as a noninvasive method for quantifying patients' hydration. We aimed to evaluate the effect of BIVA hydration status (BHS) measured before discharge on mortality and rehospitalization for AHF.

We included 369 consecutive patients discharged from the cardiology department from a third-level hospital with a diagnosis of AHF. On the basis of BHS, patients were grouped into three categories: hyper-hydration (>74.3%), normo-hydration (72.7-74.3%) and dehydration (<72.7%). Appropriate survival techniques were used to evaluate the association between BHS and the risk of death and readmission for AHF.

At a median follow-up of 12 months (interquartile range, IQR: 5-19), 80 (21.7%) deaths and 93 (25.2%) readmissions for AHF were registered. The mortality and readmission rates for the BHS categories were hyper-hydration (3.28 and 3.83 per 10 persons-years); normo-hydration (1.43 and 2.68 per 10 persons-years); and dehydration (2.24 and 2.53 per 10 persons-years) (P < 0.05 for all comparisons). In an adjusted analysis, BHS displayed a significant association with mortality (P = 0.004), with a higher mortality risk in those with hyperhydration. Likewise, BHS showed to linearly predict AHF-readmission risk [hazard ratio 1.06 (1.03-1.10); P = 0.001 per increase in 1%].

In patients admitted with AHF, BHS assessed before discharge was independently associated with the risk of death and AHF-readmission.