Estimated plasma volume is not a robust indicator of the severity of congestion in patients with heart failure

Background: Congestion is the main cause of morbidity and a prime determinant of survival in patients with heart failure (HF). However, the assessment of congestion is subjective and estimation of plasma volume (ePV) has been suggested as a more objective measure of congestion. This study aimed to explore the relationships and interactions between ePV, the severity of congestion and survival using a nationwide registry.Methods: Of the 1054 patients with HF enrolled in the registry, 769 had sufficient data to calculate ePV (using the Duarte, Kaplan, and Hatrim equations) and relative plasma volume status (rPVS), and these patients were subsequently included in the present analysis. The severity of congestion was assessed using a 6-point congestion score (CS). Patients were divided into three groups according to the degree of congestion.Results: Out of four equations tested, only ePV(Duarte) and rPVS were statistically higher in patients with severe congestion as compared to patients with no congestion (p<0.001 for both). Both ePV(Duarte )(r = 0.197, p<0.001) and rPVS (r = 0.153, p<0.001) showed statistically significant correlations with CS and both had a modest accuracy (70.4% for ePV(Duarte )and 69.4% for rPVS) to predict a CS >= 3. After a median follow up of 496 days, both ePV(Duarte) (OR:1.14,95%CI:1.03-1.26, p = 0.01) and rPVS (OR:1.02, 95%CI:1.00-1.03, p = 0.03) were associated with all-cause mortality after adjusting for demo-graphic and clinical variables. However, none of the indices were associated with mortality following the introduction of CS to the models (p>0.05 for both).Conclusions: Elevated ePV(Duarte) and rPVS were indicators of congestion but with a limited robustness, and either parameter could be clinically useful when a comprehensive clinical evaluation of congestion is not feasible.