Speaker
Jeffrey Carson, MD, MACP
Principal Investigator and Study Chair
MINT Trial
Provost-New Brunswick, Rutgers Biomedical Health Sciences
Distinguished Professor of Medicine
Richard C. Reynolds, M.D. Chair in General Internal Medicine
Rutgers, Robert Wood Johnson Medical School
Keywords
Transfusion; MI; MINT; Anemia; Clinical trials
Key Points
- Anemia is common in patients with acute MI. Due to the lack of evidence, indications for red blood cell transfusion in patients with MI are controversial. Prior to the completion of the MINT trial, three trials had compared transfusion thresholds in a total of 820 patients, and the results were inconsistent. Trials in other clinical settings suggest the use of restrictive transfusion strategy, which is a lower hemoglobin level, is safe. Most trials conducted prior to the MINT trial suggested that a restrictive transfusion strategy was comparable to a liberal transfusion strategy.
- The MINT trial investigators looked at 30-day mortality and several outcomes including MI, heart failure, stroke, bleeding, infection, and clot. None of these relative risks or confidence intervals are significant, suggesting that you could safely use a restrictive transfusion strategy for these patients. The previous trials suggest that when you randomize people to either more or less blood, those who receive less blood get about 40% less blood overall in these studies.
- Prior to the MINT trial, investigators detected very little difference between liberal and restrictive transfusion strategies. However, they saw very wide confidence intervals, which made it difficult to determine the best way to manage patients in this context.
- The objective of the MINT trial was to determine whether the risk of death or MI through 30 days differed with a restrictive transfusion strategy with a hemoglobin threshold of 7 to 8 g/dL as compared to a liberal transfusion strategy with a hemoglobin threshold of 10 g/dL among patients with an acute MI and a hemoglobin concentration of less than 10 g/dL.
- The team enrolled patients across 144 sites who fit the following criteria: 18 years or older, had an STEMI or NSTEMI, had Types 1, 2, 4b, or 4c MI, and had a hemoglobin concentration of less than 10 g/dL within 24 hours of enrollment.
- They utilized 2 transfusion strategies, restrictive and liberal. In the restrictive strategy, transfusion was permitted, but not required, when the hemoglobin concentration was less than 8 g/dL and strongly recommended when the concentration was less than 7 g/dL or when angina symptoms were not controlled with medications. For the liberal strategy, 1 unit of packed red blood cells were administered following randomization, and red blood cells were transfused to maintain a hemoglobin concentration greater than or equal to 10 g/dL through hospital discharge or 30 days.
- There were 3 primary limitations of the MINT trial. The assigned strategy was not masked; trial results were not adjusted for multiple comparisons; and although pre-specified, cardiac death was not designated as primary, secondary, or tertiary outcome or adjudicated.
- The results of the MINT trial did not demonstrate a statistically significant difference in the rate of 30-day death or recurrent MI in patients with acute MI and anemia assigned to a restrictive compared to a liberal transfusion strategy. Additionally, while not statistically significant, the point estimates for the primary outcome and secondary outcomes consistently favored a liberal transfusion strategy. Finally, heart failure and other safety outcomes were comparable in the two transfusion groups.
- In contrast to other clinical settings, the MINT trial results suggest that a liberal transfusion strategy has the potential for clinical benefit with an acceptable risk of harm and may be the most prudent approach to transfusion in anemic patients with acute MI.
Learn more
Read more about the MINT trial.
Discussion Themes
-When did you consent the patients – before or after the cath lab? We consented them as early in the hospitalization as we could. Some patients were consented before cath and others were consented after. In general, we tried not to consent patients until their hemoglobin was less than 10 in most situations. Whenever it was less than 10, then we consented them when we could get to the patient, but that varied. There was a solid mix of pre- and post- cath lab.
-Could you discuss the journal review process? Was there substantial disagreement among the authors, reviewers, and editors regarding the trial conclusions or clinical implications? There were differing opinions. One of our reviewers was incredibly helpful in helping us frame the relative risk confidence interval concepts that I described, which helped us shape the language. I think that the journal bought into that and helped us do it. It wound up being a very collaborative, constructive process. In general, I think as these things go, it was quite positive. There was some negotiation about how we would describe some of our conclusions, but overall, it was a good experience.
Tags
#pctGR, @Collaboratory1