Calculated plasma volume status and prognosis in chronic heart failure

Plasma volume (PV) expansion hallmarks worsening chronic heart failure (CHF) but no non-invasive means of quantifying volume status exists. Because weight and haematocrit are related to PV, they can be used to calculate relative PV status (PVS). We tested the validity and prognostic utility of calculated PVS in CHF patients.

First, we evaluated the agreement between calculated actual PV (aPV) and aPV levels measured using (125)Iodine-human serum albumin. Second, we derived PVS as: [(calculated aPV - ideal PV)/ideal PV] × 100%. Third, we assessed the prognostic implications of PVS in 5002 patients from the Valsartan in Heart Failure Trial (Val-HeFT), and validated this in another 246 routine CHF outpatients. On analysis, calculated and measured aPV values correlated significantly in 119 normal subjects and 30 CHF patients. In the Val-HeFT cohort, mean (+SD) PVS was -9 ± 8% and related to volume biomarkers such as brain natriuretic peptide (BNP). Over 2 years, 977 (20%) patients died. Plasma volume status was associated with death and first morbid events in a 'J-shaped' fashion with the highest risk seen with a PVS > -4%. Stratification into PVS quartiles confirmed that a PVS > -4% was associated with increased mortality (unadjusted hazard ratio 1.65, 95% confidence interval 1.44-1.88, χ(2)  = 54, P < 0.001) even after adjusting for 22 variables, including brain natriuretic peptide. These results were mirrored in the validation cohort.

Relative PVS calculated from simple clinical indices reflects the degree to which patients have deviated from their ideal PV and independently relates to outcomes. The utility of PVS-driven CHF management needs further evaluation.