The controversy remains unresolved around  transfusion strategies in patients with acute myocardial infarction and anaemia, with a major study failing to meet its primary endpoint of benefit for a liberal transfusion strategy.

However the investigators in the MINT study cautioned that potential harms of a restrictive transfusion strategy cannot be excluded.

The multinational RCT enrolled 3,506 patients with acute MI and anaemia from centres in the US, Canada, France, Brazil, New Zealand and Australia.

Participants has haemoglobin concentration levels less than 10 g/dL and were randomised to receive either a liberal strategy of having red blood cells transfused to maintain the haemoglobin at or above 10 g/dL, or a restrictive strategy in which transfusion was permitted only when the haemoglobin concentration was less than 7 or 8 g/dL.

The mean 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 haemoglobin 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 randomisation.

MINT trial overall consistently favors a liberal transfusion threshold. Time to change practice? @NEJM @nih_nhlbi #AHA23 pic.twitter.com/km8990LCtZ

— Jordan Strom, MD, MSc, FACC, FASE (@DocStrom) November 11, 2023

During the 30-day follow up there was no significant difference between restrictive and liberal strategies in the primary trial endpoint, a composite of all-cause death and recurrent heart attack (16.9% vs 14.5%, respectively (RR 1.15; 95% CI 0.99-1.34).

Death occurred in 9.9% and in 8.3% of the patients with the restrictive and liberal strategies, respectively (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).

The study investigators noted that cardiac death was more common in people treated with a restrictive transfusion strategy (5.5%) compared to death among those treated in the liberal strategy (3.2%).

Heart failure and other 30-day clinical outcomes were similar in both groups, suggesting there is no undue risk to more liberal transfusions.

Study lead investigator Professor Jeffrey Carson of Rutgers Robert Wood Johnson Medical School in New Brunswick, New Jersey, said that despite the neutral outcome, the safety of the liberal transfusion strategy  favoured this approach as the more prudent option.

“The study results require a nuanced interpretation. While the trial did not produce a statistically significant difference between the two transfusion strategies for the primary outcome, the results suggest the possibility of liberal transfusion benefits without undue risk,” he said.

“Future research is needed to further resolve the controversy around transfusion decisions for people with anaemia and heart attack,” Professor Carson added.

The results were presented at AHA 2023 and also published in NEJM (link here).

The limbic will be hosting an AHA 2023 highlights webinar on 5th December where Prof Jason Kovacic and an expert panel will present key clinical studies from the conference and discuss the impacts for practice. Register Here: https://thelimbic.com/cardiology/aha-2023-highlights-through-an-australian-lens/