Myocardial Ischemia and Transfusion - MINT
Contribution To Literature:
The MINT trial showed that in patients with acute MI and anemia (Hgb <10 g/dL), a liberal transfusion goal (Hgb ≥10 g/dL) was not superior to a restrictive strategy (Hgb 7-8 g/dL) with respect to 30-day all-cause death and recurrent MI.
The goal of this trial was to compare the effect of a liberal vs. restrictive blood transfusion strategy on acute myocardial infarction (MI) in patients with concomitant anemia.
Patients with a hemoglobin (Hgb) concentration <10 g/dL experiencing MI were randomized to a liberal (n = 1,755) or restrictive (n = 1,749) blood transfusion strategy during hospitalization. The liberal strategy arm received 1 unit of packed red blood cells (PRBC) on randomization and additional transfusions as needed to maintain Hgb concentration ≥10 g/dL. Transfusion in the restrictive arm was permitted for Hgb <8 g/dL, strongly recommended for Hgb <7 g/dL, and required for persistent angina refractory to pharmacotherapy regardless of Hgb.
- Total number of enrollees: 3,504
- Duration of follow-up: 30 days
- Mean patient age: 72 years
- Percentage female: 45%
- Age ≥18 years
- ST-segment elevation or non–ST-segment elevation myocardial infarction (STEMI or NSTEMI), respectively, on presentation or during index admission
- Hgb <10 g/dL within 24 hours of randomization
- Uncontrolled acute bleeding requiring non–cross-matched blood transfusion
- Participant declined transfusion
- Anticipated cardiac surgery during index admission
- Palliative treatment intent
Other salient features/characteristics:
- Percentage with NSTEMI: 81%
- Percentage with type 1 MI: 42%
- Percentage with multivessel coronary artery disease: 65%
- Percentage with acute heart failure: 22%
- Mean units of PRBC transfused, restrictive vs. liberal strategies: 0.7 vs. 2.5 units
The primary outcome, composite of all-cause death or recurrent nonfatal MI, for restrictive vs. liberal transfusion strategies at 30 days, was: 16.9% vs. 14.5% (risk ratio [RR] 1.15, 95% confidence interval [CI] 0.99-1.34, p = 0.07).
Secondary outcomes for restrictive vs. liberal transfusion strategies at 30 days:
- All-cause death: 9.9% vs. 8.3%, RR 1.19 (95% CI 0.96-1.47)
- Recurrent nonfatal MI: 8.5% vs. 7.2%, RR 1.19 (95% CI 0.94-1.49)
Additional prespecified outcomes for restrictive vs. liberal transfusion strategies at 30 days:
- Heart failure: 5.8% vs. 6.3%, RR 0.92 (0.71-1.20)
- Cardiac death: 5.5% vs. 3.2%, RR 1.74 (95% CI 1.26-2.40)
Prespecified subgroup analysis of primary outcome, restrictive vs. liberal transfusion strategies:
- Type 1 MI: RR 1.32 (95% CI 1.04-1.67)
- Chronic or acute heart failure or reduced ejection fraction: RR 1.25 (95% CI 1.02-1.52)
The MINT trial demonstrated that, in patients with acute MI and comorbid anemia, a liberal transfusion strategy targeting Hgb concentration ≥10 g/dL was not superior to a restrictive target of 7-8 g/dL with respect to all-cause death or nonfatal MI at 30 days. Though not significant, there was a trend toward increased events of both the primary composite endpoint and its components in the restrictive strategy arm.
There have been limited data to guide transfusion thresholds for acute MI complicated by anemia. The REALITY trial (n = 668) previously demonstrated noninferiority of a restrictive transfusion strategy in MI with respect to 30-day major adverse cardiovascular events. However, the study authors noted that the noninferiority margin of 1.25 may include clinically relevant harm. Moreover, the restrictive strategy was no longer noninferior on prespecified analysis at 1 year. Considering these data, the trend toward clinical benefit observed in MINT suggests that a liberal transfusion strategy in MI may be reasonable to consider without an appreciably increased risk of harm.
Carson JL, Brooks MM, Hébert PC, et al., on behalf of the MINT Investigators. Restrictive or Liberal Transfusion Strategy in Myocardial Infarction and Anemia. N Engl J Med 2023;Nov 11:[Epub ahead of print].
Presented by Dr. Jeffrey Carson at the American Heart Association Scientific Sessions, Philadelphia, PA, November 11, 2023.
Clinical Topics: Acute Coronary Syndromes
Keywords: Acute Coronary Syndrome, AHA23, Anemia, Blood Transfusion
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