The potential role of erythropoietin in chronic heart failure: from the correction of anemia to improved perfusion and reduced apoptosis?

Besides stimulating erythropoiesis, erythropoietin (EPO) exerts powerful proangiogenic and antiapoptotic effects. These erythropoiesis-independent effects are potentially useful as a supplement for the treatment of chronic heart failure (CHF). EPO may improve microvascular capacity of ischemic myocardial tissue and could thereby (partially) restore myocardial function. In addition, EPO could protect cardiomyocytes from hypoxic damage and prevent them from apoptosis. However, the clinical value of these erythropoiesis-independent effects for the treatment of CHF remains to be elucidated. Small-sized trials evaluating the effects of EPO treatment on surrogate endpoints in patients with CHF showed positive effects in general; however, their mutual results are not always unambiguous. Moreover, increasing hematocrit levels with EPO has been associated with increased blood viscosity and an inherent risk of thromboembolic events. A currently running multicenter phase III trial is designed to provide clarity concerning the effects of EPO on outcome and safety in patients with CHF. Focusing primarily on outcome, however, does not provide insight into the mode of action and isolated benefits of the erythropoiesis-independent effects of EPO. Further exploration of these effects is a key issue to gain knowledge of the full potential of EPO for the treatment of CHF.