Are non-invasive estimations of plasma volume an accurate measure of congestion in patients with chronic heart failure?

Abstract

We report associations between different formulae for estimating plasma volume status (PVS) and clinical and ultrasound markers of congestion in patients with chronic heart failure (CHF) enrolled in the Hull Lifelab registry. Cohort 1 comprised patients with data on signs and symptoms at initial evaluation (n=3505). Cohort 2 included patients with ultrasound assessment of congestion [lung B-line count, inferior vena cava (IVC) diameter, jugular vein distensibility (JVD) ratio] (N=341). Two formulae for PVS were used: (a) Hakim (HPVS) and (b) Duarte (DPVS). Results were compared with clinical and ultrasound markers of congestion. Outcomes assessed were mortality and the composite of heart failure (HF) hospitalisation and all-cause mortality. In cohort 1, HPVS was associated with mortality [hazard ratio (HR) per unitary increase=1.02 (1.01-1.03); P<0.001]. In cohort 2, HPVS was associated with B-line count (HR) = 1.05 [95% confidence interval (CI) (1.01-1.08); P=0.02] and DPVS with the composite outcome [HR=1.26 (1.01-1.58); P=0.04]. HPVS and DPVS were strongly related to haemoglobin concentration and HPVS to weight. After multivariable analysis, there were no strong or consistent associations between PVS and measures of congestion, severity of symptoms, or outcome. By contrast, log[NTproBNP] was strongly associated with all three. Amongst patients with CHF, HPVS and DPVS are not strongly or consistently associated with clinical or ultrasound evidence of congestion, nor clinical outcomes after multivariable adjustment. They appear only to be surrogates of the variables from which they are calculated with no intrinsic clinical utility.