Recombinant erythropoietin (Epogen) improves cardiac exercise performance in children with end-stage renal disease.

To determine the effects of anemia in children with end-stage renal disease, we studied cardiac performance before and 1 and 6 months after recombinant erythropoietin (Epogen). Children with end-stage renal disease were included if they had significant anemia [hematocrit (Hct) < 30%]. Epogen 50 U/kg was given subcutaneously or intravenously three times per week until the Hct was > or = 33%. Echocardiography, cardiac output (acetylene rebreathing), and treadmill (modified Bruce) tests were performed. Boys (9) and girls (9), 11.9 +/- 5.6 years, were given Epogen and the Hct increased (from 21.7 +/- 2.7% to 33.4 +/- 2.1%, P = 0.001). Heart rate decreased (P = 0.04) and stroke volume did not change. Blood pressure did not change. Cardiac thickness, chamber dimensions, left ventricular wall stress, velocity of circumferential fiber shortening, and indices of diastolic function were normal and did not change after Epogen. Exercise time increased (from 10.3 +/- 1.9 to 11.2 +/- 1.9 min, P = 0.01) after 1 month of Epogen. Resting oxygen consumption (VO2) decreased (from 7.8 +/- 1.8 to 6.9 +/- 1.4 ml/min per kg, P = 0.01) 1 month after Epogen and peak exercise VO2 did not change after Epogen. There were no differences in exercise tests between the 1 and 6 month measurements. Exercise tolerance improves after the short-term correction of anemia and there is no further improvement after long-term correction.