Restrictive or Liberal Transfusion Strategy in Myocardial Infarction and Anemia

Abstract

Background: A strategy of administering a transfusion only when the hemoglobin level falls below 7 or 8 g per deciliter has been widely adopted. However, patients with acute myocardial infarction may benefit from a higher hemoglobin level.

Methods: In this phase 3, interventional trial, we randomly assigned patients with myocardial infarction and a hemoglobin level of less than 10 g per deciliter to a restrictive transfusion strategy (hemoglobin cutoff for transfusion, 7 or 8 g per deciliter) or a liberal transfusion strategy (hemoglobin cutoff, <10 g per deciliter). The primary outcome was a composite of myocardial infarction or death at 30 days.

Results: A total of 3504 patients were included in the primary analysis. The mean (±SD) number of red-cell units that were transfused was 0.7±1.6 in the restrictive-strategy group and 2.5±2.3 in the liberal-strategy group. The mean hemoglobin level was 1.3 to 1.6 g per deciliter lower in the restrictive-strategy group than in the liberal-strategy group on days 1 to 3 after randomization. A primary-outcome event occurred in 295 of 1749 patients (16.9%) in the restrictive-strategy group and in 255 of 1755 patients (14.5%) in the liberal-strategy group (risk ratio modeled with multiple imputation for incomplete follow-up, 1.15; 95% confidence interval [CI], 0.99 to 1.34; P = 0.07). 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); myocardial infarction occurred in 8.5% and 7.2% of the patients, respectively (risk ratio, 1.19; 95% CI, 0.94 to 1.49).

Conclusions: In patients with acute myocardial infarction and anemia, a liberal transfusion strategy did not significantly reduce the risk of recurrent myocardial infarction or death at 30 days. However, potential harms of a restrictive transfusion strategy cannot be excluded. (Funded by the National Heart, Lung, and Blood Institute and others; MINT ClinicalTrials.gov number, NCT02981407.).

Figure 1.. Hemoglobin Level and Number of Units of Red-Cell Transfusions.

Panel A shows the mean (±SD) hemoglobin level at baseline, day 1, day 2, and day 3 in the restrictive-strategy group and the liberal-strategy group. I bars indicate 95% confidence intervals. Panel B shows the number of units of red cells transfused in the two groups.

Figure 2.. Trial Outcomes at 30 Days.

Shown are the unadjusted risk ratios for the primary, secondary, and other outcomes in patients assigned to a restrictive transfusion strategy as compared with those assigned to a liberal transfusion strategy. The estimate for the primary model with imputed missing data was a risk ratio of 1.15 (95% CI, 0.99 to 1.34; P = 0.07).

Figure 3.. Cumulative Incidence of Myocardial Infarction or Death (Primary Outcome) or Death from Any Cause at 30 Days.

Shown are Kaplan–Meier estimates of the cumulative 30-day incidence of a composite of myocardial infarction or death (Panel A) and death from any cause (Panel B) after the censoring of data for patients at the time of withdrawal or loss to follow-up. The insets in each panel show the same data on an expanded y axis.

Figure 4.. Subgroup Analysis of Myocardial Infarction or Death.

Shown is the unadjusted risk ratio for myocardial infarction or death (primary outcome) in the restrictive-strategy group as compared with the liberal-strategy group, according to prespecified subgroup. CHF denotes chronic heart failure, eGFR estimated glomerular filtration rate, LVEF left ventricular ejection fraction, NSTEMI non–ST-segment elevation myocardial infarction, and STEMI ST-segment elevation myocardial infarction.