Restrictive vs. Liberal Transfusion in Myocardial Infarction: Implications for Clinical Practice

Mar 62 min read

Introduction

Blood transfusion strategies in patients with acute myocardial infarction (MI) and anemia have long been debated, with clinical guidelines citing insufficient data to establish definitive hemoglobin thresholds. The recently published Myocardial Infarction and Transfusion (MINT) trial provided new insights into this area. Now, a patient-level meta-analysis by Carson et al., published in NEJM Evidence, integrates data from four major trials to evaluate the comparative effects of restrictive (hemoglobin threshold of 7–8 g/dl) versus liberal (threshold of 10 g/dl) transfusion strategies in MI patients.

Study Overview and Methods

This meta-analysis pooled individual patient data from four randomized trials, including the MINT trial, to provide a more precise estimate of the impact of transfusion strategies. A total of 4,311 patients were analyzed, with the primary composite outcome being 30-day mortality or recurrent MI. Secondary outcomes included cardiac mortality, heart failure, and all-cause mortality at six months.

EHR-based Sepsis Alert — **Primary and Secondary 30-Day Outcomes**

Key Findings

The primary composite outcome occurred in 15.4% of patients in the restrictive transfusion group and 13.8% in the liberal group (RR 1.13, 95% CI, 0.97–1.30).
30-day mortality was slightly higher in the restrictive group (9.3%) compared to the liberal group (8.1%) (RR 1.15, 95% CI, 0.95–1.39).
Cardiac mortality at 30 days was significantly higher in the restrictive group (5.5% vs. 3.7%; RR 1.47, 95% CI, 1.11–1.94).
All-cause mortality at six months was also increased in the restrictive group (20.5% vs. 19.1%; HR 1.08, 95% CI, 1.05–1.11).
Rates of heart failure and other safety outcomes were similar between groups (RR 0.89, 95% CI, 0.70–1.13).

*Cumulative Incidence of Death or Myocardial Infarction at 30 Days and All-Cause Death at 180 Days.*

Clinical Implications

These findings suggest that a restrictive transfusion strategy may not be as safe as previously assumed for patients with MI and anemia. While prior studies in other clinical settings (e.g., gastrointestinal bleeding, critical care) have supported restrictive transfusion, the data in the MI population indicate a potential survival benefit with a more liberal approach.

Pathophysiological Considerations

Myocardial ischemia is highly dependent on oxygen delivery, which is limited by hemoglobin concentration and coronary perfusion. In MI, where oxygen demand-supply mismatch is already critical, restrictive transfusion strategies may exacerbate ischemia, leading to increased cardiac mortality.

Conclusion

This patient-level meta-analysis challenges the existing paradigm favoring restrictive transfusion strategies in MI patients. While a definitive shift in transfusion guidelines awaits further validation, these findings emphasize the need for a more individualized approach, particularly in high-risk patients with MI. Clinicians should weigh the potential risks of restrictive transfusion strategies against the benefits of maintaining higher hemoglobin levels in this vulnerable population.

REFERENCES

Carson JL, Fergusson DA, Noveck H, et al. Restrictive versus Liberal Transfusion in Myocardial Infarction — A Patient-Level Meta-Analysis. NEJM Evid 2025;4(2). DOI: 10.1056/EVIDoa2400223.