Effects of restrictive vs liberal transfusion strategies on mortality in patients with acute myocardial infarction and anemia: The 6-month follow up primary results of the MINT trial

Abstract

Abstract Background The Myocardial Ischemia and Transfusion (MINT) trial identified a statistically non-significant increase in risk of 30-day death or myocardial infarction (MI) (primary endpoint) and all-cause death and a statistically significant increase in cardiac death in patients with an acute MI and anemia assigned to a restrictive transfusion strategy compared to a liberal transfusion strategy. Purpose To determine the effect of a restrictive versus a liberal transfusion strategy on all-cause and cause-specific death 6-months post-randomization (secondary endpoint). Methods The MINT trial randomized 3,504 patients with MI and hemoglobin <10 g/dL to a restrictive (hemoglobin threshold of 7 or 8 g/dL) or liberal (hemoglobin threshold of <10 g/dL) transfusion strategy implemented during the index hospitalization. Sites contacted patients at 30-days and 6-months post-randomization and recorded patient vital status, date of death, and site-reported cause of death (categorized as cardiac, non-cardiac, or unknown). A competing risk analysis (cumulative incidence estimation and Fine-Gray models) was conducted to estimate the effect of transfusion strategy on all-cause and cause-specific death. Results Patients were enrolled from 6 countries between 2017 and 2023; average age was 72 years, and 46% were female. Vital status at 6-months was obtained for 3419 (97.6%) randomized patients (restrictive: 98.1%; liberal: 97.0%); 2,690 (76.8%) patients were alive and 729 (20.8%) had died. At 6-months, all-cause death occurred in 376 patients in the restrictive arm (21.7%) and 353 in the liberal arm (20.5%), hazard ratio [HR]: 1.07, 95% CI: 0.93–1.24. Compared to the liberal arm, a greater proportion of deaths in the restrictive arm were cardiac (41.8% vs. 29.8%). The risk of cardiac death was significantly higher in patients in the restrictive arm (9.0% vs. 6.1%, HR: 1.52; 95% CI: 1.19–1.94) whereas risk of non-cardiac death (HR: 0.87; 95% CI: 0.70–1.08) and unknown cause of death (HR: 0.88; 95% CI: 0.64–1.21) did not differ between the restrictive and the liberal arms. Conclusions In patients with acute MI and anemia, the 6-month incidence of all-cause death did not differ with a restrictive versus a liberal transfusion strategy. However, the numerically higher rate of all-cause mortality, seen with the restrictive strategy at 30-days, persisted through 6-months and was driven by cardiac causes. The long-term findings from the MINT trial suggest that a restrictive transfusion strategy may be harmful for patients with MI and anemia.