Red blood cell (RBC) transfusion thresholds are based on levels of hemoglobin (Hb) according to the Association for the Advancement of Blood & Biotherapies (AABB) guidelines. These guidelines recommend a conservative technique (<7 g/dL) to decrease the risks and preserve the blood supply. However, their safety in patients with acute myocardial infarction (AMI) remains uncertain. AMI affects millions of individuals every year, with anemia in up to 40% of elderly patients. Liberal transfusion may improve the myocardial oxygen delivery but elevates the risk of complications like circulatory overload and pulmonary edema.
The REALITY and MINT trials investigated different Hb thresholds in AMI but found contradictory results. It highlighted the need for further evidence to guide the transfusion methods in this population. The purpose of these guidelines is to provide suggestions for RBC transfusion in patients with AMI. AABB authorized this guideline in March 2024. An international multidisciplinary panel of anesthesiologists, cardiologists, transfusion specialists, hematologists, patient partners, and methodologists guided this development. The process involved meta-analysis, systematic review, and structured panel voting, as well as transparent management of conflicts of interest.
The panel specifically addressed whether hospitalized AMI patients should receive transfusions at a restrictive Hb threshold or a more liberal threshold (9 -10 g/dL). These guidelines only applied to stable AMI patients without hemodynamic instability. The panel focused on patient-centered outcomes such as recurrent MI, mortality, stroke, acute heart failure, and transfusion-related adverse events. Minimal important differences (MIDs) for these outcomes were defined using surveys and expert consensus.
Evidence was drawn from four randomized controlled trials (RCTs) involving 4311 patients, primarily the REALITY and MINT trials, identified through a systematic review up to April 2024. Risk ratio and odds ratio were calculated with the Peto odds ratio for rare events. Panel value was prioritized to reduce mortality and recurrent MI. Ultimately 70% of the panel voted in favor of recommending a transfusion threshold of <10 g/dL rather than <9 g/dL. The guideline was completed in February 2025 and approved by the AABB Board of Directors after international peer review.
The international panel suggests starting RBC transfusion at a Hb threshold of below 10 g/dL in hospitalized patients with AMI. This suggestion underlines the need for transfusion choices based on clinical context, patient preferences, and hemodynamic stability when making transfusion decisions.Â
This study found a 1.2% absolute reduction in 30-day mortality with the liberal transfusion method, which exceeded the minimal relevant difference of the panel. Rates of recurrent MI were not significantly different between groups. However, transfusion-related acute lung injury and circulatory overload were more common in the liberal group.
The panel concluded that the potential mortality benefit exceeded the risks and resource conservation benefits of a limited strategy and recommended an increased transfusion threshold. Clinicians can reduce transfusion-related hazards by optimizing fluid balance, reducing transfusion rates, and considering peri-transfusion diuretics or renal replacement therapy when appropriate. The recommendation further highlights the role of patient blood management strategies to prevent anemia and avoid unnecessary transfusions.
More research is required to refine transfusion thresholds according to patient-specific factors like type of MI, severity of coronary disease, and ventricular function. In conclusion, while the panel supports RBC transfusion for AMI patients with Hb levels < 10 g/dL, clinical judgment, informed consent, and tailored treatment remain essential.
Reference: Pagano MB, Stanworth SJ, Dennis J, et al. Red cell transfusion in acute myocardial infarction: AABB international clinical practice guidelines. Ann Intern Med. 2025. doi:10.7326/ANNALS-25-00706
