Written by Peter Liu
Spoon Feed
In patients with acute MI, restrictive blood transfusion thresholds (hemoglobin 8g/dL) had similar rates of all-cause death and recurrent MI at 6 months. However, the 6-month hazard of cardiac death was 52% greater (9.0% vs 6.1%; HR 1.52, 95%CI, 1.19–1.94) in the restrictive transfusion group, largely due to increased cardiac death during the first 30 days.
Synopsis
The MINT trial evaluated the 6-month mortality outcomes of restrictive versus liberal blood transfusion strategies in patients with acute myocardial infarction (MI) and anemia. The study enrolled 3,504 patients with hemoglobin levels <10 g/dL, randomized to a restrictive strategy (transfusion at ≤8 g/dL) or a liberal one (≤10 g/dL). By 6 months, 21.7% in the restrictive arm and 20.5% in the liberal arm had died, showing no significant difference in overall mortality (HR 1.07, 95%CI 0.93–1.24). Notably, the restrictive group had higher early cardiac mortality, suggesting potential risks with lower hemoglobin thresholds immediately post-MI. [AI-generated]
Results from MINT don’t clear the air around liberal blood transfusions in AMI
“If the heart is hypoperfused, increase the oxygen delivered to it by increasing the concentration of hemoglobin.” This tantalizing idea has captivated many clinicians and researchers but with frustratingly inconclusive support from clinical trials. Take the recent, similar REALITY RCT, which concluded noninferiority of a restrictive transfusion strategy. Compared to REALITY , MINT is much higher-powered; still, it was only powered to show a reduction of over 20% in the primary composite endpoint of MI or death. In the primary analysis, there was numerically lower MI or death at 30 days with liberal blood transfusion, which nearly met significance (14.5% vs. 16.9%; RR 1.15, 95%CI 0.99-1.34, p=0.07), indicating possible benefit to liberal blood transfusions, but the sample size may have been too small to conclusively detect it. Overall, results from MINT make a weak case for a possible small benefit of liberal blood transfusion in patients with type 1 MI (hemoglobin goal of 10g/dL). This decision would have to be weighed against the risks of the transfusion itself, with an increase in transfusion-related circulatory overload noted in the trial, and an increase in healthcare cost.
Source
Restrictive or Liberal Transfusion Strategy in Patients With Acute Myocardial Infarction and Anemia: 6-Month Mortality in the MINT Trial. Circulation. 2024 Sep 24;150(13):1064-1066. doi: 10.1161/CIRCULATIONAHA.124.069917. Epub 2024 Sep 2. PMID: 39221566.
