The role of anemia in the progression of congestive heart failure. Is there a place for erythropoietin and intravenous iron?

Anemia is found in about one-third of all cases of congestive heart failure (CHF). The most likely common cause is chronic kidney insufficiency (CKI), which is present in about half of all CHF cases. The CKI is likely to be due to the renal vasoconstriction that often accompanies CHF and can cause long-standing renal ischemia. This reduces the amount of erythropoietin (EPO) produced in the kidney and leads to anemia. However, anemia can occur in CHF without CKI and is likely to be due to excessive cytokine production (for example, tumor necrosis factor-alfa (TNF-alfa) and interleukin-6 (IL-6)), which is common in CHF and can cause reduced EPO secretion, interference with EPO activity in the bone marrow and reduced iron supply to the bone marrow. The anemia itself can worsen cardiac function, both because it causes cardiac stress through tachycardia and increased stroke volume, and because it can cause a reduced renal blood flow and fluid retention, adding further stress to the heart. Long-standing anemia of any cause can cause left ventricular hypertrophy (LVH), which can lead to cardiac cell death through apoptosis and worsen the CHF. Therefore, a vicious circle is set up wherein CHF causes anemia, and the anemia causes more CHF and both damage the kidneys worsening the anemia and the CHF further. We have termed this vicious circle the cardio renal anemia (CRA) syndrome. Patients with CHF who are anemic are often resistant to all CHF medications resulting in being hospitalized repeatedly. Many studies also demonstrate that these patients die more rapidly than their non-anemic counterparts do. In addition, they have a more rapid deterioration in their renal function and can end up on dialysis. There is now evidence from both uncontrolled and controlled studies that early correction of the CHF anemia with subcutaneous EPO and intravenous (i.v.) iron improves shortness of breath and fatigue, cardiac function, renal function and exercise capability, dramatically reducing the need for hospitalization. For these reasons, it is not surprising that quality of life has also been shown to improve. As both CHF and end-stage renal disease (ESRD) are rapidly increasing, the possibility that these twin conditions can be improved by the adequate treatment of anemia offers new hope for slowing the progression of both conditions.