Anemia: The Point of Convergence or Divergence for Kidney Disease and Heart Failure?

Cardiorenal anemia syndrome refers to the simultaneous presence of anemia, heart failure (HF), and chronic kidney disease (CKD) that forms a pathologic triangle with an adverse impact on morbidity and mortality. The reciprocal relationships among these 3 components have been the subject of a number of trials with inconsistent and sometimes paradoxic results. In this paper, the pathophysiologic concepts underlying interactions among these 3 conditions are discussed. Then, the similarities and dissimilarities of the relationships between anemia and either HF or CKD are considered; explanations are provided for differences in the results of the currently available studies. Erythropoietin-stimulating agent protocols are usually based on the results of studies designed for the CKD population, and upper hemoglobin target levels are chosen to avoid cardiovascular complications. It is not yet clear whether those renal guidelines are optimal for patients with HF, especially because those patients may have reversible components of kidney dysfunction, both HF and renal parameters improving with anemia correction. We review these issues and suggest a pragmatic approach to the care of patients with HF until such time that controlled trials establish definitive anemia treatment goals that are dynamic and disease specific, rather than those that adopt a more simplistic hemoglobin-specific approach.