Background Plasma volume (PV) expansion is a hallmark feature of worsening heart failure that is notoriously underestimated by clinical examination. While radioisotope assays optimally quantify PV status, numerous haemodialysis-based equations also exist for its estimation. The prognostic utility of such formulas in chronic heart failure (CHF) is unknown.
Methods We analysed the relation between estimated PV status and mortality in 246 outpatients with CHF (mean (±SD) age 67±13 years, NYHA class 2±1, LVEF 28±8%). PV status was calculated (Hakim RM, et al) by subtracting the patients actual PV ((1-haematocrit) × (a + (b × weight)); a and b are gender-specific constants) from their ideal PV ((c × weight); c=gender-specific constant).
Results Median (±IQR) PV status was—261±550 ml with 78% and 21% of patients having PV contraction and expansion, respectively. Patients with PV excess had significantly higher creatinine and lower albumin levels. Over a median follow-up of 13±16 months, 36 (15%) patients died. PV status predicted mortality (HR 1.001, 95% CI 1.001 to 1.002, p=0.001) in a graded fashion (Abstract 104 figure 1A) and did so independently of NYHA class, LVEF, weight, haematocrit and creatinine. A PV status ≤−178 ml optimally predicted survival (ROC AUC 0.68, p=0.0007) and conferred a 75% reduced hazard for death (HR 0.16, 95% CI 0.07 to 0.37, p<0.0001, Abstract 104 figure 1B).
Conclusions Calculating plasma volume status in CHF patients appears prognostically useful and suggests that dehydration is better tolerated than volume excess in these individuals and that targeting therapy to achieve a plasma volume status ≤178 ml might increment survival.
- Heart failure
- plasma volume