Relationship of resting hemoglobin concentration to peak oxygen uptake in heart failure patients

Anemia is frequent in chronic heart failure (HF). To calculate what change in peak oxygen uptake ( $ {\dot {\bf V}} $O2) should be expected in the event of changes in hemoglobin concentration, we studied the correlation between peak $ {\dot {\bf V}} $O2 and hemoglobin concentration in a large HF population. We carried out retrospective analysis of all cardiopulmonary exercise tests (CPET) performed in our HF Clinic between June 2001 and March 2009 in HF patients who had a resting hemoglobin concentration measurement taken within 7 days of the CPET. We collected 967 CPETs, 704 tests were considered maximal and analyzed. We identified 181 patients (26%) as anemic. Peak $ {\dot {\bf V}} $O2 was lower (P < 0.001) in anemic patients (971 ± 23 ml/min) compared with nonanemic (1243 ± 18 ml/min). The slope of the $ {\dot {\bf V}} $O2 vs. hemoglobin ratio was 109 ml/min/g/dl at peak exercise. This correlation remained significant also when several confounding variables were analyzed by multivariate analysis. As an average, each gram of hemoglobin accounts, at peak exercise, for 109 ml/min change in $ {\dot {\bf V}} $O2 which is equivalent to 0.97 ml/min/kg. Therefore, in HF patients anemia treatment should increase $ {\dot {\bf V}} $O2 by 109 ml/min for each g/dl of hemoglobin increase. Am. J. Hematol. 2010. © 2010 Wiley‐Liss, Inc.