Differences in Red Blood Cell Mass Profiles Impact Intravascular Volume and Outcome Risk in Chronic Heart Failure

AIMS: To identify different red blood cell mass (RBCM) profiles, separate from haemoglobin concentrations, and their impact on blood volume expansion and clinical outcomes in chronic heart failure. METHODS AND RESULTS: RBCM was measured at hospital discharge using standardized nuclear medicine indicator-dilution methodology in patients following diuretic treatment for clinical congestion. Individual RBCM phenotypes were prospectively identified and analysed for heart failure-related mortality or first rehospitalization over 1 year. Of 132 patients, 42 (32%) demonstrated normal RBCM, 36 (27%) RBCM deficit (true anaemia), and 54 (41%) RBCM excess (erythrocythemia). Dilutional 'anaemia' defined by haemoglobin <12 g/dL with normal or an excess in RBCM with plasma volume expansion was identified in 37 (28%) patients. There were 61 composite outcome events, which included 38 deaths (29% of cohort) occurring over the 1 year follow-up period 14/36 (39%) in RBCM deficit, 12/42 (29%) in normal RBCM, and 12/54 (22%) in RBCM excess subgroups. By Kaplan-Meier and multivariate analyses, RBCM excess was independently associated with the best event-free survival while RBCM deficit (true anaemia) the poorest outcomes; both compared with normal RBCM (P < 0.001). Dilutional 'anaemia' demonstrated a lower risk compared with true anaemia (P = 0.03). CONCLUSIONS: Markedly different RBCM profiles are identifiable among comparably compensated heart failure patients, and this variability carries significant implications for post-hospital outcomes. Novel to this analysis and in contrast to RBCM deficit is the independent association of RBCM excess with better event-free survival compared with normal RBCM. The distinction of RBCM profiles to guide risk stratification and individualized patient management strategies warrants further study.