Abstract 15774: Red Cell Distribution Width Relates to Exercise Capacity in Chronic Heart Failure but Provides Prognostic Information Incremental to Peak Oxygen Consumption
Background: Red cell distribution width (RDW), an index of the variability in size of circulating erythrocytes, is a surrogate of many aberrations (iron deficiency, inflammation, oxidative stress) that may drive chronic heart failure (CHF) progression. Whilst an elevated RDW powerfully predicts mortality in CHF, little is known about its relation to exercise performance and its ability to prognosticate when adjusted for peak oxygen consumption (PVO2).
Methods: We analysed the relation between red cell indices, exercise capacity, and survival in 136 patients with systolic CHF (mean [±SD] age 67±13y, RDW 14.4±1.5%, PVO2 18±8 mL/kg/min, 71% male, 68% with ≥ moderate LV impairment).
Results: Higher RDWs correlated to lower PVO2 (P=0.0002) levels and oxygen uptake efficiency slopes (P<0.01), and higher VE/VCO2 slopes (P<0.001). On multiple regression, RDW related to PVO2 independently of age, haemoglobin, and peak heart rate (R2=0.49, P<0.0001). Over a median (±IQR) follow-up of 3.8±3.0 years, 22 (16%) patients died. Both RDW (HR 1.39, P=0.001) and PVO2 (HR 0.87, P=0.001) independently predicted mortality. An RDW>15% (ROC AUC 0.71, P=0.002) and PVO2≤14mL/kg/min (ROC AUC 0.74, P<0.0001) were optimally predictive with each conferring 4-fold escalated risks for death. In incremental prognostic models, the addition of RDW to PVO2 increased hazard ratio (Fig A) and chi-squared (Fig B) values significantly, with the combination of an RDW>15% and PVO2<14mL/kg/min identifying those at a 6-fold enhanced risk of mortality.
Conclusions: An increased RDW relates to exercise intolerance in CHF but provides prognostic information incremental to PVO2. Ameliorating drivers of RDW expansion such as iron deficiency might durably improve functional capacity and survival in this cohort.
- © 2011 by American Heart Association, Inc.