Research highlights:
- A multinational study compared test results of heart attack patients with anemia who received blood transfusions when their hemoglobin concentration levels were 8 g/dL or 10 g/dL.
- Although the results did not reach statistical significance, they showed that blood transfusions to keep hemoglobin levels above 10 g/dL for anemic patients hospitalized with heart attacks may improve their health.
- As the largest study to evaluate blood transfusion thresholds in people after a heart attack, the results could help guide clinicians’ decision-making when treating heart attack patients with anemia.
Embargoed until Saturday, November 11, 2023 at 10:10 a.m. ET
PHILADELPHIA, Nov. 11, 2023 — The indications for red blood cell transfusions in people hospitalized with heart attacks are controversial, but a randomized controlled trial of more than 3,500 people shows benefits in expanding the transfusion approach. Breakthrough science presented today at the American Heart Association suggests that may be the case, according to a new report. Academic Session 2023. The conference, to be held in Philadelphia from November 11-13, is the premier global gathering to exchange updates on the latest scientific advances, research, and evidence-based clinical practices in cardiovascular science. . The full manuscript is available today. New England Medical Journal.
Previous studies on blood transfusion strategies for patients hospitalized with heart attacks have yielded conflicting results. Doctors believed that giving more blood would increase the amount of oxygen to the heart and improve outcomes. However, more blood transfusions can increase the risk of fluid overload and rare infections. Uncertainty about when to transfuse blood to heart attack patients led to this trial, called Myocardial Ischemia Transfusion (MINT).
“People who are hospitalized with a heart attack often have a low red blood cell count or anemia,” said Dr. Robert Wood, a distinguished professor of medicine at Rutgers Robert Wood Johnson Medical School in New Brunswick, New Jersey. says one study author, Jeffrey L. Carson, MD. He is the Richard C. Reynolds Professor of General Internal Medicine. “We believe our results suggest that a more permissive transfusion approach may be beneficial for these patients without significant risks.”
In the MINT trial, anemia was defined as a hemoglobin concentration less than 10 g/dL. Participants were randomly assigned to a restrictive or liberal transfusion strategy. In the massive transfusion strategy, red blood cells were transfused to maintain hemoglobin above 10 g/dL at discharge or throughout the 30-day period. A restrictive transfusion strategy allows transfusion only if the hemoglobin concentration is less than 8 g/dL and strongly recommends transfusion if the hemoglobin concentration is less than 7 g/dL or in the case of cardiac symptoms that cannot be controlled with medications. I did.
The analysis revealed the following:
- 295 of 1,749 participants (16.9%) in the restrictive transfusion trial group experienced a recurrent heart attack or death, compared with 255 of 1,755 participants (14.5%) in the restrictive transfusion group. .
- Cardiac death was more common in patients treated with a restrictive transfusion strategy (5.5%) compared with patients treated with a restrictive transfusion strategy (3.2%).
- Heart failure and other 30-day clinical outcomes were similar in both groups, suggesting that more generous transfusions carry no undue risk.
“Study results require nuanced interpretation. Although this trial did not produce a statistically significant difference between the two transfusion strategies with respect to the primary outcome, the results suggest that the results should be tolerated without undue risk.” “These findings suggest that there may be benefits from significant blood transfusions,” Carson said. “The MINT results suggest that a massive transfusion strategy may be the most prudent approach for patients with heart attack or anemia.”
Background and details of the trial:
- The randomized controlled trial enrolled 3,506 participants from April 2017 to April 2023 from 144 hospitals in the United States, Canada, France, Brazil, New Zealand, and Australia.
- All participants (mean age 72 years, 45% women, 55% men) had had a heart attack and had hemoglobin concentration levels below 10 g/dL. A normal hemoglobin level is 12 to 13 g/dL, Carson said.
- Many of the participants also had other health conditions, including a history of heart attack (33%), heart failure (30%), diabetes (54%), and kidney disease (46%).
- The primary endpoint of the trial was a composite of all-cause death and recurrent heart attack over a 30-day period after trial randomization.
- Secondary outcomes included a composite of individual components of the primary outcome and all-cause death, heart attack, unplanned coronary revascularization due to recurrent cardiac symptoms, or readmission for a heart-related diagnosis within 30 days. was included. The cause of death was classified as cardiac, noncardiac, or unknown. Other test results included heart failure and infection.
Carson said the MINT results should be interpreted with caution because the analysis was not adjusted for multiple statistical tests. Other limitations include that treating clinicians knew which strategy participants were assigned to and that not all participants in the liberal transfusion group with hemoglobin concentration levels >10 g/dL were discharged from the hospital. can be mentioned. This was often due to clinical discretion, such as concerns about fluid overload or timing of discharge. Furthermore, cause of death was classified by the research team at the study hospital, as recurrent myocardial infarction was the only outcome confirmed by an independent committee.
“Future research is needed to further resolve the controversy surrounding blood transfusion decisions for people with anemia or heart attacks,” Professor Carson said.
Co-authors, disclosures, and funding sources are listed in the abstract.
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