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 ( VO(2)) should be expected in the event of changes in hemoglobin concentration, we studied the correlation between peak VO(2) 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 VO(2) was lower (P < 0.001) in anemic patients (971 +/- 23 ml/min) compared with nonanemic (1243 +/- 18 ml/min). The slope of the VO(2) 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 VO(2) which is equivalent to 0.97 ml/min/kg. Therefore, in HF patients anemia treatment should increase VO(2) by 109 ml/min for each g/dl of hemoglobin increase.