Effect of Red Blood Cell Transfusion Strategy on Clinical Outcomes Among Patients With Acute Myocardial Infarction Undergoing Revascularization: A Prespecified Analysis of the MINT Trial.

Abstract

Background: The MINT trial (Myocardial Ischemia and Transfusion; N=3504) randomized patients with acute myocardial infarction (MI) and hemoglobin ≤10 g/dL to liberal (maintain hemoglobin ≥10 g/dL) or restrictive (maintain hemoglobin ≥8 g/dL) red blood cell transfusion. The results suggested a benefit on 30-day death or MI with a liberal transfusion strategy. The effect of transfusion in patients with acute MI undergoing revascularization is unclear.

Methods: In this prespecified analysis of the MINT trial, patients who underwent revascularization (n=1002) before randomization but during index hospitalization were compared with those who did not (n=2442). The primary outcome was 30-day death or MI; secondary outcomes included 30-day death, recurrent MI, the composite of death, recurrent MI, ischemia-driven unscheduled revascularization, or readmission for ischemic cardiac diagnosis, heart failure, and cardiac death. Multivariable log-binomial regression was used to determine the relative risks of the primary and secondary outcomes by transfusion strategy for revascularized and nonrevascularized patients with interaction terms.

Results: Patients undergoing revascularization were younger, more often female, and had fewer comorbidities than those who did not. There was no significant interaction between revascularization and assigned transfusion strategy for any outcome except cardiac death. Compared with liberal transfusion, restrictive transfusion increased the risk of 30-day cardiac death among nonrevascularized patients (relative risk, 2.45 [1.58-3.81]) but not among revascularized patients (relative risk, 0.97 [0.59,-1.60]; interaction P=0.006).

Conclusions: In this analysis of the MINT trial, revascularization did not alter the effect of the randomized transfusion strategy on 30-day death or MI. The hypothesis-generating finding that a restrictive transfusion strategy was associated with an increased risk of cardiac death among patients with anemia and acute MI who do not undergo revascularization requires confirmation.

Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT02981407.