• Gerard T Portela, Jeffrey L Carson, Sonja A Swanson, John H Alexander, Paul C Hébert, Shaun G Goodman, Philippe Gabriel Steg, Marnie Bertolet, Jordan B Strom, Dean A Fergusson, Tabassome Simon, Harvey D White, Howard A Cooper, J Dawn Abbott, Sunil V Rao, Bernard R Chaitman, Christopher B Fordyce, Renato D Lopes, Benoit Daneault, Maria M Brooks, and MINT Investigators.
• Department of Epidemiology, University of Pittsburgh, Pittsburgh, Pennsylvania (G.T.P., S.A.S.).
• Ann. Intern. Med. 2024 Nov 1; 177 (11): 148914981489-1498.

BackgroundThe optimal hemoglobin threshold to guide red blood cell (RBC) transfusion for patients with acute myocardial infarction (MI) and anemia is uncertain.ObjectiveTo estimate the efficacy of 4 individual hemoglobin thresholds (<10 g/dL [<100 g/L], <9 g/dL [<90 g/L], <8 g/dL [<80 g/L], and <7 g/dL [<70 g/L]) to guide transfusion in patients with acute MI and anemia.DesignPrespecified secondary analysis of the MINT (Myocardial Ischemia and Transfusion) trial using target trial emulation methods. (ClinicalTrials.gov: NCT02981407).Setting144 clinical sites in 6 countries.Participants3492 MINT trial participants with acute MI and a hemoglobin level below 10 g/dL.InterventionFour transfusion strategies to maintain patients' hemoglobin concentrations at or above thresholds of 10, 9, 8, or 7 g/dL. Protocol exceptions were permitted for specified adverse clinical events.MeasurementsData from the MINT trial were leveraged to emulate 4 transfusion strategies and estimate per protocol effects on the composite outcome of 30-day death or recurrent MI (death/MI) and 30-day death using inverse probability weighting.ResultsThe 30-day risk for death/MI was 14.8% (95% CI, 11.8% to 18.4%) for a <10-g/dL strategy, 15.1% (CI, 11.7% to 18.2%) for a <9-g/dL strategy, 15.9% (CI, 12.4% to 19.0%) for a <8-g/dL strategy, and 18.3% (CI, 14.6% to 22.0%) for a <7-g/dL strategy. Absolute risk differences and risk ratios relative to the <10-g/dL strategy for 30-day death/MI increased as thresholds decreased, although 95% CIs were wide. Findings were similar and imprecise for 30-day death.LimitationUnmeasured confounding may have persisted despite adjustment.ConclusionThe 30-day risks for death/MI and death among patients with acute MI and anemia seem to increase progressively with lower hemoglobin concentration thresholds for transfusion. However, the imprecision around estimates from this target trial analysis precludes definitive conclusions about individual hemoglobin thresholds.Primary Funding SourceNational Heart, Lung, and Blood Institute.

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