Background
Hypothetical risk of liberal transfusion vs restrictive
administering more blood could result in more frequent heart failure from fluid overload, infection from immunosuppression, thrombosis from higher viscosity, and inflammation.
What was the study design? How many sites?
Open-label, randomized, controlled trial conducted at 144 sites across six countries. Pragmatic design to maximize real-world applicability.
What were key baseline characteristics?
-mean age,
-%Men/Women
-Type 1 vs. Type 2 MI
Mean age: 72 years
45.5% women
55.8% type 2 MI; 41.7% type 1 MI
High comorbidity burden (≈⅓ with prior MI, PCI, or heart failure, ~50% with renal insufficiency)
How many patients were enrolled and analyzed?
Answer:
3506 enrolled; 3504 included in analysis
Can we make any formal conclusions about the results?
Additional studies needed to make definite conclusions
Hypothetical benefit of liberal transfusion vs restrictive
From a mechanistic perspective, blood transfusion may decrease ischemic injury by improving oxygen delivery to myocardial tissues and reduce the risk of reinfarction or death
What were the inclusion criteria? (3 things)
Adults ≥18 years
ST-elevation or non–ST-elevation MI (type 1, 2, 4b, or 4c MI)
Hemoglobin <10 g/dL within 24 hours before randomization
Did the transfusion strategies achieve meaningful separation in hemoglobin levels?
Yes. Liberal group received 3.5× more blood (4325 vs. 1237 units). Hgb was 1.3 g/dL higher on day 1 and 1.6 g/dL higher on day 3 compared with restrictive strategy.
what were the RR of death and MI at 30 days?
Death: RR 1.19 (95% CI, 0.96–1.47)
Recurrent MI: RR 1.19 (95% CI, 0.94–1.49)
Point estimates favored the liberal strategy, but not statistically significant.
What were the strengths of the trial
3504 patients enrolled Wide range of clinical presentations and comorbidities. 98.3% patients completed 30 day follow up
What do previous large transfusion-threshold trials in general hospital populations show?
Across >21,000 patients in various clinical settings, restrictive transfusion strategies reduced blood use by ~50% without increasing morbidity or mortality. However, these studies largely excluded MI patients—highlighting a key evidence gap.
Primary Exclusion Criteria
Uncontrolled bleeding, palliative care, planned cardiac surgery during admission, refusal of transfusion.
What were the primary outcome results? Was the RR statistically significant?
-Restrictive: 16.9% vs. Liberal: 14.5%
-Risk ratio: 1.16 (95% CI, 1.00–1.35)
The difference did not reach statistical significance.
Which subgroup showed the largest difference?
Type 1 MI patients
Notable Limitations to the Study
1) Trial intervention not masked from HCPs. 2) Cause of death not centrally adjudicated 3)Some non-adherence to protocol, especially in the liberal arm (86.3% adherance). 4) No multiplicity correction for secondary outcomes. 5) Potential heterogeneity due to inclusion of large type 2 MI population
What is the primary objective of the MINT trial?
To determine whether a restrictive transfusion strategy (Hgb 7–8 g/dL) differs from a liberal strategy (Hgb <10 g/dL) in risk of death or MI at 30 days in patients with acute MI and anemia.
Describe the two transfusion strategies being compared.
Restrictive: transfuse if Hgb <7 g/dL (strongly recommended) or <8 g/dL (permitted), or if angina uncontrolled.
Liberal: transfuse 1 unit immediately, then maintain Hgb ≥10 g/dL until discharge or day 30.
Both strategies used single-unit transfusions with repeat Hgb checks.
What were the differences in rates of heart failure or TACO between the two groups?
HF rates were similar (5.8% restrictive vs. 6.3% liberal).
TACO was more common in the liberal group (1.3% vs. 0.5%).
What was the RR for Type 1 MI vs Type 2 MI?
Restrictive associated with more events (RR 1.32; 95% CI, 1.04–1.67).
Type 2 MI showed no signal of difference
Was there evidence of clinical benefit for liberal vs. restrictive transfusion?
95% CI suggests clinical benefit for liberal over restrictive strategy. Risk of MI 2.4% lower for liberal vs restrictive
What is the controversy surrounding transfusion thresholds in MI patients?
Prior small randomized trials (n≈820 total) produced mixed results regarding benefit or noninferiority of restrictive strategies.
What were the secondary outcomes?
individual components of the primary outcome (MI or death at 30 days) & the composite outcome of death, MI, ischemia-driven unscheduled coronary revasc, or readmission to the hospital for an ischemic cardiac condition within 30 days
Were there any statistically significant secondary outcomes?
Cardiac death was higher in the restrictive group (5.5% vs. 3.2%; RR 1.74), but the risk of other clinical-outcome events did not differ significantly be- tween the two groups
FINAL Jeapardy
What does UPtoDATE say regarding transfusion of stable patients with ACS/MI
"Patients with risk factors for reinfarction such as incomplete revascularization or high-risk coronary anatomy (eg, left main, multivessel disease) and who do not have risk factors (eg, heart failure) for transfusion complications may benefit from transfusion if their hemoglobin is low (eg, <10 g/dL), ie, a liberal transfusion strategy."
How did results of MINT compare to CRIT trial and Pilot study
Mint Pilot: 7 deaths (restrictive), 1 death (liberal). CRIT: point estimates favor restrictive group