No difference between liberal, restrictive transfusion strategies in acute MI, anemia
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Key takeaways:
- A liberal vs. restrictive transfusion strategy yielded similar rates of death or MI at 30 days in patients with acute MI and anemia.
- Point estimates for most outcomes favored the liberal strategy.
PHILADELPHIA — In patients with acute MI and anemia, there was no difference between liberal and restrictive transfusion strategies for the composite outcome of death and MI at 30 days, according to results of the MINT trial.
The NHLBI-funded trial, presented at the American Heart Association Scientific Sessions and simultaneously published in The New England Journal of Medicine, included 3,504 patients (mean age, 72.1 years; 45.5% women) with acute MI (STEMI or non-STEMI) and anemia, defined as a hemoglobin threshold of less than 10 g/dL. Patients were randomly assigned to a liberal transfusion strategy (hemoglobin cutoff < 10 g/dL) or a restrictive transfusion strategy (hemoglobin cutoff 7 g/dL or 8 g/dL).
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“Anemia is common in patients with heart attacks,” Jeffrey L. Carson, MD, provost and Distinguished Professor of Medicine and Richard C. Reynolds, MD, Chair in General Internal Medicine at the New Brunswick, New Jersey, campus of Rutgers Biomedical and Health Sciences, said during a press conference. “A normal hemoglobin level is 13 g/dL in men and 12 g/dL in women. The indications for red-cell transfusion in heart attack patients are controversial. Trials in other settings suggest the use of a restrictive transfusion strategy is safe. The objectives of the MINT trial were to determine whether the risk of death or MI differed using less blood transfusions and lower hemoglobin levels of 7 g/dL to 8 g/dL, as compared to using more blood transfusions and a hemoglobin level of 10 g/dL among patients with a heart attack and a blood count less than 10 g/dL.”
Approximately half of patients underwent angiography before randomization, 55.8% had type 2 MI, 41.7% had type 1 MI, 81.3% had non-STEMI, mean hemoglobin level was 8.6 g/dL, median creatinine level was 1.4 mg/dL, approximately one-third had history of MI, PCI or HF and about half had renal insufficiency, according to the researchers.
The primary outcome was MI or death at 30 days.
The mean number of red-cell units transfused was 0.7 in the restrictive group and 2.5 in the liberal group. Mean hemoglobin level was 1.3 g/L at day 1 and 1.6 g/dL lower at day 3 in the restrictive group than in the liberal group, Carson said.
The primary outcome occurred in 16.9% of the restrictive group compared with 14.5% of the liberal group (RR modeled with multiple imputation for incomplete follow-up = 1.15; 95% CI, 0.99-1.34; P = .07), Carson said. The unadjusted RR was 1.16 (95% CI, 1-1.35).
For the individual components of the primary outcome, death occurred in 9.9% of patients with the restrictive strategy compared with 8.3% of the patients with the liberal strategy (RR = 1.19; 95% CI, 0.96-1.47) and MI occurred in 8.5% of the restrictive group compared with 7.2% of the liberal group (RR = 1.19; 95% CI, 0.94-1.49).
Cardiac death occurred more often in the restrictive group (5.5% vs. 3.2%; RR = 1.74; 95% CI, 1.26-2.4) and transfusion-associated cardiac overload events were less frequent in the restrictive-strategy group than in the liberal-strategy group (0.5% vs. 1.3%; RR = 0.35; 95% CI, 0.16-0.78).
There was no difference between the groups in other clinical outcome events, the researchers found.
In patients with type 1 MI, the primary outcome occurred more often in the restrictive group than in the liberal group (RR = 1.32; 95% CI, 1.04-1.67), but in patients with type 2 MI, there was no difference in the primary outcome between the groups, Carson and colleagues reported.
“While not statistically significant, the results consistently favored a liberal transfusion strategy,” Carson said. “In contrast to other clinical settings, the trial results suggest that a liberal transfusion strategy has the potential for clinical benefit with low risk. A liberal transfusion strategy may be the most prudent approach to transfusion in anemic patients with myocardial infarction.”
In a discussion at the press conference, Martin B. Leon, MD, professor of medicine and chief innovation officer and director of the Cardiovascular Data Science Center for the Division of Cardiology at Columbia University Irving Medical Center, and founder of the Cardiovascular Research Foundation, said: “The definitive home-run statistical endpoint was not quite achieved, but so many of the things are more in favor of a more liberal transfusion strategy, that that will likely be the general interpretation [of the trial]. Specifically, cardiovascular death was reduced from 5.5% to 3.2%; that’s a significant reduction. There were other prespecified subgroups that also showed greater impact. The final conclusion is that this is not definitely superior to employ in all patients a liberal strategy, but I think it will be interpreted that the effect size is somewhat small but meaningful. The liberal strategy will probably be the dominant strategy in most patient cohorts, as the point estimates are very consistent.”
Reference:
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Samin K. Sharma, MD, FACC, FSCAI
I am still surprised that people keep doing trials of patients with MI and anemia. There are already two trials, CRIT and REALITY, that have been done essentially comparing 8 g/dL of hemoglobin to 10 g/dL. It turns out that 8 g/dL is OK and doing 10 g/dL does not help. Studies have shown that if you give more blood, patients can go into heart failure or get more symptoms. This is the largest trial in this area, and it has the same message as the previous ones: We do not need the liberal strategy. A restrictive strategy keeping the hemoglobin around 8 g/dL is probably beneficial. Giving a blood transfusion causes many inflammatory changes and sometimes prothrombotic effects, so a liberal strategy may even be harmful. This large trial has fully supported the conclusion that 8 g/dL of hemoglobin in patients with STEMI is completely fine; we do not need to try to make it to 10 g/dL.
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Carson JL, et al. LBS.02. Hot topics in management of coronary artery disease/acute coronary syndrome. Presented at: American Heart Association Scientific Sessions; Nov. 11-13, 2023; Philadelphia.
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