Transfusion of Fresh but Not Stored Blood Reduces Infarct Size and Improves Cardiac Function Following Acute Myocardial Infarction In Anemic Rats

Anemia is a predictor of poor outcomes in acute myocardial infarction (MI) and may increase the degree of ischemia, resulting in greater tissue injury. The only existing therapeutic intervention used to acutely correct anemia is red blood cell (RBC) transfusion, although its effectiveness at improving outcomes in anemic subjects following MI remains controversial. We have previously shown that transfusion of fresh blood in anemic rats following MI decreased infarct size, and improved cardiac function and survival (Hu et al. Transfusion 2010; 50:243-251). However, it was not known if the transfusion of stored blood, which develops a series of chemical and corpuscular changes collectively known as the “storage lesion”, would be equally effective in this model.

Acute MI was induced by coronary artery ligation in 49 male Sprague-Dawley rats, 38 of which were made anemic (Hb = 80–90 g/L) using a combination of dietary iron deprivation and phlebotomy, and 11 with normal Hb levels. Rat blood was stored for 7 days in CPDA-1 to induce a storage lesion similar to the one seen in human blood stored under identical conditions for 28 days (d'Almeida et al. Transfusion Medicine 2000; 10:291-303). Anemic animals were randomly assigned to one of three groups: i) fresh blood transfusion (stored for <4 hours) to increase the Hb to 100 g/L, ii) transfused with stored blood to increase the Hb to 100 g/L, or iii) no transfusion. At 24 hours post-MI, infarct size, cardiac function and survival rates were determined.

A similar degree of left ventricular (LV) myocardial ischemia (area at risk) was induced in all groups (P=NS). In agreement with previous results, the infarct size to area at risk ratios were significantly increased in the anemic (Hb 80–90 g/L) animals compared to non-anemic MI controls, and transfusion of fresh blood to a target Hb level of 100 g/L after MI decreased infarct size (P<0.05) and improved both systolic (+dP/dt_max) and diastolic (−dP/dt_min) LV function compared to anemic animals (P<0.05). However, the transfusion of stored blood into anemic animals post-MI did not have these effects when compared to the group receiving fresh blood (P<0.05). Furthermore, survival was increased in anemic animals receiving fresh blood (9/11; P<0.05) but not stored blood (7/14; P=NS) compared to the non-transfused group (5/13).

The prolonged storage of blood negates the beneficial effects of fresh blood transfusion, which include reductions in infarct size, and improvements in cardiac function and short-term survival following acute MI in this animal model.

(This study was supported by the Canadian Institutes of Health Research, Canadian Blood Services and the Bayer Partnership Fund).

No relevant conflicts of interest to declare.