Liberal Transfusion Strategy May Benefit Patients with MI and Anemia

A liberal transfusion strategy with a hemoglobin cutoff of 10 g/dL appears to improve outcomes for patients with myocardial infarction (MI) and anemia, according to the results of a large multinational study published in the New England Journal of Medicine and presented at the 2023 American Heart Association Scientific Sessions.

"In contrast to other clinical settings, the trial results suggest that a liberal transfusion strategy has the potential for clinical benefit with an acceptable risk of harm. A liberal transfusion strategy may be the most prudent approach to transfusion in anemic patients with MI,” lead author Jeffrey Carson, MD, told Weekly Report. Carson is also lead author of AABB’s Red Blood Cell Transfusion Guidelines published in October. Carson is provost, distinguished professor of medicine, and Richard C. Reynolds, MD, chair in general internal medicine at Rutgers Robert Wood Johnson Medical School in New Brunswick, N.J.

The researchers found that 16.9% (295/1,749) of patients, who were treated according to a restrictive transfusion strategy experienced recurrent heart attack or died within 30 days (composite primary outcome), compared to 14.5% (255/1,755) of patients randomized to a liberal transfusion approach. While the results did not reach statistical significance, the findings provide important information about a group of patients lacking evidence for or against a liberal approach.

“The study results require a nuanced interpretation. While the trial did not produce a statistically significant difference between the two transfusion strategies for the primary outcome [recurrent MI and death], the results suggest the possibility of liberal transfusion benefits without undue risk,” Carson said in a press release from the American Heart Association.

The findings come from the Myocardial Ischemia and Transfusion (MINT) trial, which is the largest to date evaluating transfusion thresholds in people after heart attack. The study included adults with ST-segment elevation or non–ST-segment elevation MI. Patients also had anemia, defined as a hemoglobin level less than 10 g/dL within 24 hours before randomization.

Patients were randomized to restrictive or liberal transfusion strategies. In the restrictive group, transfusion was permitted but not required with the Hb less than 8 g per dL; transfusion was strongly recommended for Hb levels of less than 7 g/dL or when anginal symptoms were not controlled with medications. Patients in the liberal-strategy group received one unit of packed RBCs after randomization; RBCs were transfused as necessary to maintain Hb at or above 10 g/dL until hospital discharge or 30 days. Patients in both groups received one unit at a time followed by Hb measurement.

This analysis included 3,504 patients with a mean age of 72.1 years; 45.5% of the patients were women. Notably, patients had frequent coexisting illnesses, with roughly a third having a history of MI, percutaneous coronary intervention or heart failure; nearly half had renal insufficiency. The average prerandomization hemoglobin level was 8.6 g/dL.

Prespecified secondary endpoints included the following:

• Death had occurred in 9.9% in the restrictive-strategy group and 8.3% in the liberal-strategy group.
• MI occurred in 8.5% and 7.2% of the patients, respectively.
• Thirty-day death, MI, ischemia-driven unscheduled coronary revascularization, or readmission to the hospital for an ischemic cardiac condition occurred in 19.6% and 17.4%, respectively.
• Cardiac death was more common among patients in the restrictive group (5.5% versus 3.2%).

Notably, the risk of heart failure at 30 days was similar for the two groups (5.8% and 6.3%). Other clinical factors were similar at 30 days, suggesting that there is little harm associated with a more liberal approach. However, there were fewer transfusion-associated cardiac overload (TACO) events in the restrictive-strategy group (0.5% and 1.3%, respectively). The authors noted that heart failure is a “more comprehensive measure of volume overload than TACO.”