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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.).
|Hemostasis and Thrombosis|
In patients with AMI and anemia, a liberal transfusion strategy did not significantly reduce the risk for recurrent myocardial infarction or death at 30 days. However, potential harms of a restrictive transfusion strategy cannot be excluded. This was a beautifully conceived and completed trial.
A big issue is how Type 2 MI is distinguished from Type 1 MI. In my experience, type 2 MI diagnosis is very sloppy. In that subset, we may actually be comparing acute MI to sick ICU patients with troponin release, and liberal transfusion actually had a benefit here.
This is a very important study. Conventional wisdom has always been that transfusing to a hemoglobin of 10 was necessary in people with cardiac disease; patients with active cardiac issues were often not included in the trials of restricted transfusions. This was a very well done large randomized trial of patients with acute MI randomized to restrictive (hgb 7-8) verses liberal (hgb-10) transfusion requirements, and did not show a difference in 30-day outcomes including death and MI. Interestingly, subgroup analysis showed that type 1 MI did worse; that is enough for me to not apply that to this patient group. We should continue to test the absolutes of medicine that we have always held as true, as often they are proven to be not. More patients receiving transfusions developed heart failure, and transfusions are not a benign intervention.
All of the outcomes were less frequent in the group with the liberal strategy. Despite the large sample size, the confidence intervals does not confirm or discard any clinically significant difference for or against this strategy. Without any relevant adverse events reported, there is no reason to NOT use the liberal strategy in patients with AMI and hemoglobin <10 g per deciliter.