Conservative versus liberal red cell transfusion in acute myocardial infarction (the CRIT Randomized Pilot Study)

Red blood cell transfusion is common in patients with acute myocardial infarction (AMI). However, observational data suggest that this practice may be associated with worse clinical outcomes and data from clinical trials are lacking in this population. We conducted a prospective multicenter randomized pilot trial in which 45 patients with AMI and a hematocrit level ≤30% were randomized to a liberal (transfuse when hematocrit <30% to maintain 30% to 33%) or a conservative (transfuse when hematocrit <24% to maintain 24% to 27%) transfusion strategy. Baseline hematocrit was similar in those in the liberal and conservative arms (26.9% vs 27.5%, p = 0.4). Average daily hematocrits were 30.6% in the liberal arm and 27.9% in the conservative arm, a difference of 2.7% (p <0.001). More patients in the liberal arm than in the conservative arm were transfused (100% vs 54%, p <0.001) and the average number of units transfused per patient tended to be higher in the liberal arm than in the conservative arm (2.5 vs 1.6, p = 0.07). The primary clinical safety measurement of in-hospital death, recurrent MI, or new or worsening congestive heart failure occurred in 8 patients in the liberal arm and 3 in the conservative arm (38% vs 13%, p = 0.046). In conclusion, compared to a conservative transfusion strategy, treating anemic patients with AMI according to a liberal transfusion strategy results in more patients receiving transfusions and higher hematocrit levels. However, this may be associated with worse clinical outcomes. A large-scale definitive trial addressing this issue is urgently required.