Anemia and morbidity and mortality in coronary bypass surgery

Anemia is associated with increased morbidity and mortality, in community-dwelling persons, in critically ill patients and perioperatively. The exact reasons and extent of the risks induced by anemia are not known, however, nor the optimal therapeutic approach. Based on the assumption that transfusion invariably counteracts the risks associated with perioperative anemia, most studies do not exclude the confounding effects of transfusion, and anemia is inconsistently defined. Cardiovascular disease was identified as a major additional risk for anemic patients, but the combined effects of decreasing hemoglobin and comorbidities in patients with coronary stenoses have not been determined exactly. This review integrates recent data to present a more differentiated understanding of mechanisms and risks of anemia in coronary artery bypass grafting surgery.

Patients with many comorbidities are more susceptible to the effects of anemia. Some outcomes may primarily be caused by concomitant risk factors associated with anemia rather than by low hemoglobin per se. The precise interactions of anemia and comorbidities to produce worse outcomes are still unclear, as is the optimal therapeutic approach.

The review highlights recent developments on anemia in heart surgery, and advocates new studies to institute individually adapted therapies.