MINT Trial: Red Blood Cell Transfusions May Benefit Heart Attack Patients With Anemia

A study indicates that red blood cell transfusions for anemic patients hospitalized with heart attack may improve patient outcomes. The results were presented as late-breaking science at the American Heart Association’s Scientific Sessions 2023, and simultaneously published today in The New England Journal of Medicine.

Previous studies on transfusion strategies for people hospitalized with heart attack have not yielded consistent results. Doctors have postulated that providing more blood transfusions would increase the amount of oxygen for the heart and improve outcomes; however, giving more blood transfusions may increase the risk of fluid overload and lead to rare and dangerous infections. This uncertainty, as the investigators noted, led to this trial called Myocardial Ischemia and Transfusion (MINT).

This randomized controlled trial consisted of 3,506 participants (average age, 72, 45% women, 55% men) from 144 hospitals across the United States, Canada, France, Brazil, New Zealand and Australia between April 2017 and April 2023. All study subjects had a heart attack and hemoglobin concentration levels below 10 g/dL, which is below the normal concentration of 12-13 g/dL.

Restrictive Versus Liberal Transfusion

As part of the study’s liberal transfusion strategy, red blood cells were transfused to maintain the hemoglobin at or above 10 g/dL through hospital discharge or for 30 days. In the restrictive transfusion strategy, transfusion was permitted only when the hemoglobin concentration was less than 8 g/dL and strongly recommended when the hemoglobin concentration was less than 7 g/dL. The study’s primary outcome of interest was defined as the composite of all-cause mortality and recurrent heart attack through 30 days subsequent to randomization.

Liberal Transfusion Strategy Potentially “Beneficial”

The results found that nearly 17% of participants in the restrictive transfusion group experienced a recurrent heart attack or death versus 14.5% in the liberal transfusion group. The researchers observed that cardiac mortality was more common with a restrictive transfusion strategy versus those treated in the liberal strategy group (5.5% vs. 3.2%).

“Low red blood count or anemia is common among people hospitalized with heart attack,” said study author Jeffrey L. Carson, M.D., who is provost and distinguished professor of medicine at Rutgers Robert Wood Johnson Medical School in New Brunswick, New Jersey, and holds the Richard C. Reynolds chair in general internal medicine via a press release. “We believe our results suggest a more liberal transfusion approach may be beneficial for these patients without significant risk.”