Liberal blood transfusion strategy does not improve outcomes in acute MI patients with anemia: MINT study

A strategy of administering a transfusion only when the hemoglobin level falls below 7 or 8 g/dL has been widely adopted. But can a liberal transfusion strategy (hemoglobin threshold, <10 g/dL) among patients with an acute myocardial infarction and anemia improve outcomes in these patients remains debatable. A recent study published in this regard in NEJM and simultaneously presented at AHA 2023 meet has compared the restrictive strategy with more liberal one and found that the latter fails to significantly reduce the risk of recurrent myocardial infarction or death at 30 days.

From a mechanistic perspective, blood transfusion may decrease ischemic injury by improving oxygen delivery to myocardial tissues and reduce the risk of reinfarction or death. Alternatively, administering more blood could result in more frequent heart failure from fluid overload, infection from immunosuppression, thrombosis from higher viscosity, and inflammation.

The primary objective of the MINT trial was to determine whether the risk of death or myocardial infarction through 30 days differed between a restrictive transfusion strategy (hemoglobin threshold, 7 to 8 g/dL) and a liberal transfusion strategy (hemoglobin threshold, <10 g/dL) among patients with an acute myocardial infarction and anemia.

A total of 3504 patients were included in the study. 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.

The occurrence of primary-outcome was not significantly different between the two groups (16.9% in the restrictive-strategy group and 14.5% in the liberal-strategy group).

Death occurred in 9.9% of the patients with the restrictive strategy and in 8.3% of the patients with the liberal strategy; myocardial infarction occurred in 8.5% and 7.2% of the patients, respectively- both differences being not significant.

The trial population mimics patients seen in clinical practice!

“It was pragmatic, since it was designed to maximize the generalizability of the results. With few exclusions, the enrollment of 3504 patients included a wide variety of older patients who had a variety of myocardial infarction diagnoses, including both ST-segment elevation and non–ST-segment elevation and both type 1 and type 2 myocardial infarctions. In addition, the patients had many coexisting illnesses and were generally representative of patients in clinical practice with acute myocardial infarction and anemia”, noted the authors.

The authors conclude with “(the) trial end points suggest some benefit of a liberal strategy over a restrictive strategy, but additional studies would be needed to confirm that conclusion.

Source: NEJM: DOI: 10.1056/NEJMoa2307983