Transfusion Thresholds for Patients with Myocardial Infarction and Anemia

There has been a lot of interest in determining optimal red blood cell transfusion triggers, as unnecessary transfusions can cause patient morbidity and use precious resources. For most patient populations, restrictive transfusion thresholds of hemoglobin levels of 7-8 g/dL are used, however, there have been concerns about applying restrictive transfusion thresholds to all patient populations. The Myocardial Ischemia and Transfusion (MINT) trial was designed to evaluate whether the risk of death or myocardial infarction (MI) through 30 days differed between restrictive (7-8 g/dL) and liberal transfusion strategies (10 g/dL) in patients with an acute MI and anemia. Results of this study were recently published in the New England Journal of Medicine.

The study was an open-label, randomized trial conducted at 144 sites worldwide and enrolled adults with ST-segment elevation or non-ST-segment elevation MI with anemia, defined as a hemoglobin level <10 g/dL. Of note, patients with uncontrolled bleeding or who were scheduled for cardiac surgery were excluded. A total of 3,504 patients were evaluated. The mean hemoglobin level was lower in the restrictive-strategy group by 1.3 g/dL on day 1 and by 1.5 g/dL on day 3. Total number of red cell units transfused was 3.5 times higher in the liberal strategy group; a mean (±SD) number transfused in the liberal-strategy group was 2.5±2.3 versus 0.7±1.6 in the restrictive-strategy group.

A significant difference in the incidence of recurrent MI or death at 30 days in the two groups was not observed. Death occurred in 9.9% of the patients with the restrictive strategy and in 8.3% of the patients with the liberal strategy (risk ratio 1.19; 95% CI, 0.96 to 1.47) and MI occurred in 8.5% and 7.2% of the patients, respectively (risk ratio 1.19; 95% CI, 0.94-1.49). The authors conclude that there may be other adverse effects of restrictive transfusion strategy that should be evaluated in additional studies. 

Restrictive or Liberal Transfusion Strategy in Myocardial Infarction and Anemia. Carson, J., Brooks, M. et al. The New England Journal of Medicine, 2023 Nov 11. doi: 10.1056/NEJMoa2307983. Epub ahead of print. PMID: 37952133.