MINT: Liberal or restrictive transfusion strategy in MI with anaemia? 

Although a liberal transfusion strategy did not significantly outperform a restrictive transfusion strategy in patients with myocardial infarction (MI) and anaemia, the authors of the MINT study as well as the members of the late-breaking science session panel agreed that a liberal transfusion strategy is potentially a beneficial strategy in this patient population. 

“Anaemia is a common feature in patients with MI,” said Dr Jeffrey Carson (Rutgers University, NJ, USA) [1,2]. “So far, 3 trials have compared transfusion thresholds in patients with MI (n=820) with inconsistent results.” The large, randomised-controlled, phase 3 MINT trial (NCT02981407) compared a restrictive transfusion strategy (i.e. starting transfusions at a haemoglobin level ≤7–8 g/dL) with a liberal transfusion strategy (i.e. targeting a haemoglobin level ≥10 g/dL) in patients with an acute MI and anaemia (defined as haemoglobin level <10 g/dL). The primary outcome was the risk of death or MI through 30 days. The 3,506 participants were randomised 1:1 to one of the treatment strategies.

On day 1, the haemoglobin levels increased in both groups from a mean 8.6 g/dL at baseline to 8.8 g/dL and 10.1 g/dL in the restrictive and liberal arms, respectively. Dr Carson mentioned that 66.3% of the participants in the restrictive group had received no blood units, compared with 5.1% in the liberal group. “For the primary outcome of death or MI through day 30, we observed rates of 16.9% and 14.5% in the study arms, achieving borderline significance in the liberal transfusion strategy arm (RR 1.16; 95% CI 0.99–1.34; P=0.07),” according to Dr Carson.

The effect appeared to be somewhat more pronounced in patients with type 1 MI compared with patients with type 2 MI (RR 1.32 vs RR 1.05), although there was no significant interaction. “Importantly, there was no significant increase in heart failure events, with rates of 5.8% and 6.3% in the restrictive and liberal arm, respectively (RR 0.92; 95% CI 0.71–1.20),” stressed Dr Carson.

Although the MINT trial did not demonstrate that a liberal transfusion strategy was significantly superior to a restrictive transfusion strategy in patients with MI and anaemia, the totality of the data (see Figure) suggests that a liberal transfusion strategy has the potential to deliver a clinical benefit.

Figure: MINT outcome measures within 30 days [1]



“Given the lack of acute harm associated with liberal transfusion and the preponderance of evidence favouring liberal transfusion in the largest trial to date, liberal transfusion appears to be a viable management strategy among patients with non-ST-elevation MI and type 1 MI,” decided Prof. C. Michael Gibson (Harvard University, MA, USA), discussant of the trial.

1. 
   
   1. Carson JL, et al. MINT: Restrictive versus liberal blood transfusion in patients with myocardial infarction and anaemia: results of the MINT trial. LB02, AHA Scientific Sessions 2023, 11–13 November, Philadelphia, USA.

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Posted on 29 January 202429 January 2024