Impact of Preoperative Martial Deficiency on the Level of Blood Transfusion in Programmed Cardiac Surgery (CARMATS)

Blood transfusion is expensive, and has medical and safety consequences for patients who benefit from it. In cardiac surgery, the data concerning the level of perioperative transfusion are very heterogeneous from one center to another. In a large US cohort study of 798 cardiac surgery centers and 102,470 patients undergoing coronary artery bypass surgery, the rate of blood transfusion varies from 8 to 93% depending on the center. It would appear that the largest and most experienced centers have a blood transfusion rate of around 60%.

In addition to its beneficial role in reducing mortality induced by deep or poorly tolerated anemia, current data from the literature also raise morbidity and mortality related to blood transfusion. Murphy et al. Have shown, in an English cohort of cardiac surgery, that transfusion of CGR was correlated with the occurrence of postoperative infections and ischemic events, as well as early and late excess mortality. These effects appear as early as the first transfused red blood cell, which is confirmed by a prospective Brazilian study with a hazard ratio of death occurrence of 1.2 for each RBC transfused after cardiac surgery.

Preoperative anemia is found in 25% of patients in programmed cardiac surgery and its etiologies are varied. Iron deficiency appears to be at the forefront, especially in coronary patients for whom studies report up to 48% iron deficiency anemia. It may also be vitamin B12 deficiency or folate, chronic pathologies such as renal insufficiency, or any other common cause of anemia.

According to the latest European recommendations, iron deficiency should be defined as <100 ng / mL ferritin or <300 ng / mL ferritin combined with a transferrin saturation <20%.

In cardiac surgery, iron deficiency affects 37% of preoperative patients and is associated with more frequent preoperative and postoperative anemia. It is an independent risk factor for postoperative blood transfusion, even in the absence of preoperatively associated anemia It is currently recommended to seek iron deficiency preoperatively during the discovery of any microcytic anemia and to achieve iron substitution if found. And also to seek supplemental iron deficiency in all patients with cardiac insufficiency.