Enhanced Blood Transfusions May Potentially Improve Outcomes for Heart Attack Victims Suffering from Anaemia.
A groundbreaking international clinical trial, led by Jeffrey Carson of Johns Hopkins University, has found that a liberal blood transfusion strategy for anaemic heart attack patients may improve survival rates and reduce the re-occurrence of heart attacks. The MINT trial, funded by the National Institutes of Health National Heart, Lung and Blood Institute (NHLBI), involved over 3,500 participants at 144 hospitals in six countries.
The MINT trial evaluated two transfusion strategies: liberal (keeping blood count > 10 g/dL) and restrictive (giving blood unless count < 8 g/dL). The average age of participants was 72, with 45% being women, and a large percentage had a history of previous heart attack, heart failure, diabetes, or kidney disease.
The study found a 2.4% lower frequency of mortality or recurrent heart attack when a liberal transfusion approach was used, although the result was not statistically significant. The results of the MINT trial were presented at the Late-Breaking Scientific Sessions of the 2023 American Heart Association annual conference.
Health professionals at hospitals had clinical discretion to adhere to the study's transfusion strategy while ensuring standard care for patients. Maria Mori Brooks, professor of epidemiology and biostatistics at the University of Pittsburgh School of Public Health, co-first authored the study and served as the principal investigator of the data coordinating centre for the MINT trial.
Brooks stated that the trial provides the best data to answer a question physicians face daily. She also mentioned that the trial results indicate a liberal strategy may be better, but they also suggest that the two approaches may be similar, necessitating further investigation.
Carson's work contributed to the establishment of transfusion guidelines in 2012, which physicians use to inform patient care. Updates to these guidelines were announced last month in the Journal of the American Medical Association, emphasising an individualised approach that accounts for comorbid conditions.
The latest findings from the MINT trial indicate that a liberal blood transfusion strategy may be associated with reduced mortality in patients with acute myocardial infarction (heart attacks) and anemia, compared with a restrictive transfusion strategy. However, the results contrast with the findings of the REALITY trial, which suggested increased mortality with the liberal strategy, reflecting ongoing uncertainty and the complexity of transfusion decisions in this population.
The MINT trial data also included secondary analyses showing an impact of transfusion strategy on patients' quality of life and 6-month mortality, supporting clinical decision-making that balances anemia correction with potential risks from transfusion. The key implication is that while cautious use of transfusion is often recommended, in the context of myocardial infarction with anemia, a more liberal transfusion approach might improve outcomes, though individual patient monitoring for signs of volume overload and cardiac stress remains essential.
Additional context from related research emphasizes the "double-edged sword" nature of blood transfusion in cardiac patients: while transfusions can improve oxygen delivery and myocardial function by raising hemoglobin, they may also increase blood viscosity and inflammatory responses, potentially harming heart function. Therefore, personalized strategies that dynamically assess hemoglobin levels, cardiac function, and volume status are critical to optimizing transfusion benefits while minimizing risks.
In summary, the MINT trial suggests that a liberal blood transfusion strategy may improve outcomes in anaemic heart attack patients without causing undue harm. However, the results contrast with those of the REALITY trial, underscoring the complexity of transfusion decisions in this population. The findings may inform updated guidelines supporting more flexible transfusion thresholds in this specific patient group but highlight the need for careful monitoring and further research to refine optimal transfusion strategies. The results of the MINT trial were published in the New England Journal of Medicine.
