According to the REALITY study, the largest randomized study in this setting, restrictive blood transfusion has no negative impact on clinical outcomes compared to a more liberal strategy in anemic patients with acute myocardial infarction1. The restrictive strategy resulted in fewer infections and acute lung injuries. As the overall blood use and costs were lower this strategy was considered to be the most cost-effective.
In many places, there is uncertainty about the benefits of blood transfusion in patients with acute myocardial infarction (AMI). Observational studies have reported that transfusion in patients with AMI is associated with a higher mortality rate. The optimal transfusion strategy for anemic patients with AMI is unclear. Only 2 small randomized trials have been carried out with contradictory results.
The REALITY study enrolled 666 subjects (mean age 77 years; 43% female) with AMI and hemoglobin (Hgb) 8-10 g/dl during hospital admission, who were randomly assigned to either a liberal or restrictive erythrocyte (RBC) transfusion strategy. In the restrictive strategy, transfusion was refused unless the hemoglobin was ≤8 g/dL, with a target value of 8-10 g/dl Hgb (n=324); and in the liberal strategy, transfusion was given as soon as the hemoglobin was ≤10 g/dL, with a target value of >11 g/dl Hgb (n=342).
The primary endpoint, consisting of all-cause mortality, reinfarction, stroke, and emergency percutaneous coronary intervention triggered by ischemia, was found in 11.0% of subjects receiving the restrictive strategy and 14.0% of subjects receiving the liberal strategy (HR 0.77, P<0.05 for non-inferiority, P=0.22 for superiority).
The individual components of the primary end result were found in the following percentages of subjects in the groups receiving the restrictive versus liberal transfusion strategy (HR 0.77, P<0.05 for non-inferiority, P=0.22 for superiority)
In terms of safety, subjects assigned to the restrictive strategy were significantly less likely to develop infection (0.0% vs 1.5%; P=0.03) or acute lung injury than those assigned to the liberal strategy (0.3% vs 2.2%; P=0.03). Total 30-day hospital costs amounted to €11,051 compared to €12,572 (P=0.1).
The REALITY study clearly supports the use of a restrictive strategy for blood transfusions in AMI patients with anemia. The restrictive strategy saves blood, is safe, and at least as effective in preventing ischaemic events within 30 days as a liberal strategy while saving money. Similar results in favor of a restrictive strategy were found for postcardiac and non-cardiac surgery patients.
1. Bar PG. REALITY - A Trial of Transfusion Strategies for Myocardial Infarction and Anemia. Hot Line 4 session, ESC Congress 2020, 31 Aug.