Restrictive Versus Liberal Transfusion in Patients With Type 1 or Type 2 Myocardial Infarction: A Prespecified Analysis of the MINT Trial
Andrew P. DeFilippis, J. Dawn Abbott, Brandon M. Herbert, Marnie Bertolet, Bernard Chaitman, Harvey D. White, Andrew M. Goldsweig, Tamar S. Polonsky, Rajesh Gupta, Caroline Alsweiler, Johanne Silvain, Pedro Gabriel Melo de Barros e Silva, Graham S. Hillis, Benoit Daneault, Meechai Tessalee, Mark Menegus, Sunil V. Rao, Renato D. Lópes, Paul C. Hébert, John H. Alexander, Maria M. Brooks, Jeffrey L. Carson, Shaun G. Goodman, for the MINT Investigators
Abstract
BACKGROUND: The MINT trial (Myocardial Ischemia and Transfusion) raised concern for harm from a restrictive versus liberal transfusion strategy in patients with acute myocardial infarction (MI) and anemia. Type 1 and type 2 MI are distinct pathophysiologic entities that may respond differently to blood transfusion. This analysis sought to determine whether the effects of transfusion varied among patients with a type 1 or a type 2 MI and anemia. The authors hypothesized that the liberal transfusion strategy would be of greater benefit in type 2 than in type 1 MI. METHODS: The authors compared rates of death or MI at 30 days in patients with type 1 (n=1460) and type 2 (n=1955) MI and anemia who were randomly allocated to a restrictive (threshold, 7–8 g/dL) or a liberal (threshold, 10 g/dL) transfusion strategy. RESULTS: The primary outcome of death or MI was observed in 16% of type 1 MI and 15.4% of type 2 MI patients. The rate of death or MI was higher in patients with type 1 MI randomized to a restrictive (18.2%) versus liberal (13.8%) transfusion strategy (relative risk [RR], 1.32 [95% CI, 1.04–1.67]) with no difference observed between the restrictive (15.8%) and liberal (15.1%) transfusion strategies in patients with type 2 MI (RR, 1.05 [95% CI, 0.85–1.29]). The test for a differential effect of transfusion strategy by MI type was not statistically significant ( P interaction = 0.16). CONCLUSIONS: The concern for harm with a restrictive transfusion strategy in patients with acute MI and anemia raised in the MINT primary outcome manuscript may be more apparent in patients with type 1 than type 2 MI. REGISTRATION: URL: https://www.clinicaltrials.gov ; Unique identifier: NCT02981407.