IN ADULTS with acute myocardial infarction (MI), acute anaemia was associated with a 25% higher risk of a composite outcome of 30-day death or recurrent MI compared to chronic anaemia, but anaemia acuity did not significantly alter the effectiveness of different red blood cell (RBC) transfusion strategies.
This secondary analysis of the Myocardial Ischemia and Transfusion (MINT) trial investigated whether the type of anaemia—acute versus chronic—modifies the impact of restrictive versus liberal RBC transfusion strategies on post-MI outcomes. Acute anaemia is characterized by a sudden drop in haemoglobin (Hb) levels, potentially limiting the body’s ability to adapt physiologically, whilst chronic anaemia represents a more gradual decline, potentially allowing for compensatory mechanisms. This study included a large cohort of MI patients with anaemia to examine post-transfusion 30-day outcomes, specifically assessing whether the acuity of anaemia should influence clinical transfusion decisions.
This analysis utilized data from 3,144 participants in the MINT trial, conducted across 126 hospitals in six countries. Participants were selected based on a baseline Hb level below 10 g/dL at randomization, with measurements available within 24 hours of hospital admission. Acute anaemia was defined as either a baseline Hb level above 13 g/dL for men (12 g/dL for women) with a significant drop or a decrease of 2 g/dL or more since admission; other cases were categorized as chronic anaemia. Participants were randomized to a restrictive transfusion strategy (Hb trigger of 7-8 g/dL) or a liberal strategy (Hb trigger of up to 10 g/dL). The primary outcome was a composite of death or recurrent MI within 30 days. Results showed that those with acute anaemia had a 25% increased risk of the primary outcome compared to those with chronic anaemia (adjusted risk ratio, 1.25; 95% CI, 1.05-1.48). However, the effect of the transfusion strategy on the primary outcome was consistent across both anaemia types, suggesting no significant interaction between anaemia acuity and the transfusion approach.
These findings suggest that, in MI patients with anaemia, the acuity of anaemia should not dictate the choice between restrictive and liberal RBC transfusion strategies, as the transfusion strategy’s effect remained unchanged. In clinical practice, this supports a transfusion approach based on established Hb thresholds without additional consideration of anaemia acuity, potentially streamlining decision-making for anaemic MI patients and focusing on Hb levels rather than anaemia type. Further studies may explore additional patient factors to refine transfusion practices for optimal post-MI outcomes.
Reference
Carrier FM et al. Anemia acuity effect on transfusion strategies in acute myocardial infarction: a secondary analysis of the MINT trial. JAMA Netw Open. 2024;7(11):e2442361.
