PubMed2006
Anemia, defined as a hemoglobin level of less than 12 g/dL, often is seen in congestive heart failure (CHF). It is associated with an increased mortality and morbidity and increased hospitalizations. Compared with nonanemic patients the presence of anemia also is associated with worse cardiac clinical status, more severe systolic and diastolic dysfunction, a higher beta natriuretic peptide level, increased extracellular and plasma volume, a more rapid deterioration of renal function, a lower quality of life, and increased medical costs. The only way to determine if anemia is merely a marker for more severe CHF or actually is contributing to the worsening of the CHF is to correct the anemia and see if this favorably influences the CHF. In several controlled and uncontrolled studies, correction of the anemia with subcutaneous erythropoietin (EPO) or darbepoetin in conjunction with oral and intravenous iron has been associated with an improvement in clinical status, number of hospitalizations, cardiac and renal function, and quality of life. However, larger, randomized, double-blind, controlled studies still are needed to verify these initial observations. The effect of EPO may be related partly to its nonhematologic functions including neovascularization; prevention of apoptosis of endothelial, myocardial, cerebral, and renal cells; increase in endothelial progenitor cells; and anti-inflammatory and antioxidant effects. Anemia also may play a role in increasing cardiovascular morbidity in chronic kidney insufficiency, diabetes, renal transplantation, asymptomatic left ventricular dysfunction, left ventricular hypertrophy, acute coronary syndromes including myocardial infarction and chronic coronary heart disease, and in cardiac surgery. Again, controlled studies of correction of anemia are needed to assess its importance in these conditions. The anemia in CHF mainly is caused by a combination of renal failure and CHF-induced increased cytokine production, and these can both lead to reduced production of EPO, resistance of the bone marrow to EPO stimulation, and to cytokine-induced iron-deficiency anemia caused by reduced intestinal absorption of iron and reduced release of iron from iron stores. The use of angiotensin-converting enzyme inhibitor and angiotensin receptor blockers also may inhibit the bone marrow response to EPO. Hemodilution caused by CHF also may cause a low hemoglobin level. Renal failure, cardiac failure, and anemia therefore all interact to cause or worsen each other--the so-called cardio-renal-anemia syndrome. Adequate treatment of all 3 conditions will slow down the progression of both the CHF and the chronic kidney insufficiency.