LAUSR

Background Intravascular volume is largely regulated by the kidneys but how the relative extent of volume expansion impacts outcomes in post-hospital chronic heart failure (HF) patients has not been assessed. Our hypothesis was that greater rather than lesser volume expansion is compensatory and associated with better HF-related outcomes. Methods Blood volume (BV) was prospectively measured in 87 HF patients at the time of hospital discharge (post-diuretic therapy) using a standardized nuclear medicine radiolabeled albumin indicator-dilution technique (Daxor Corp., NY, NY). A volume cut-point of ≥+25% above normal BV defined greater from lesser volume expansion. The cohort was analyzed for 1-year composite outcome of HF-related mortality or 1st re-hospitalization. Results BV expansion ≥+25% was present in 53% of the cohort with RBC mass excess (polycythemia) being the predominant contributor (74% of this subgroup). In this volume expanded subgroup (N=46) the risk for the composite endpoint was significantly lower than in the subgroup with less volume expansion (N=41; 56% with normal BV, 44% with mild-moderate BV expansion) [Fig. 1, p=0.017, RR 0.41 (0.20-0.84)]. Further, the evaluation of RBC mass as a component of intravascular volume informs the higher risk associated with true anemia [p=0.006, RR 2.78 (1.37-5.55)], but also importantly the significant reduction in risk associated with RBC polycythemia [p Conclusions The findings of this analysis indicate that persistent intravascular volume expansion (≥+25% above normal volume) is common at the time of hospital discharge despite diuretic intervention in chronic HF patients, and importantly that in post-hospital follow up the greater extent of BV expansion (compared to normal volume or mild-moderate expansion) driven mainly by RBC polycythemia is compensatory, not detrimental, and associated with better HF-related outcomes including reduced mortality. These findings provide additional insight into the pathophysiology of chronic HF and also have implications for a more individualized approach to volume assessment and management in HF patients.