A more liberal approach to red blood cell transfusions may be beneficial for heart attack patients who also have anaemia, researchers suggest.
A USA study, published in the New England Medical Journal and presented to the American Heart Association’s Scientific Sessions 2023, found the approach would not pose undue risk for patients.
The randomised controlled trial of more than 3,500 people, led by a team at Rutgers Robert Wood Johnson Medical School in New Brunswick, New Jersey, suggests there may be benefits to an expanded transfusion approach.
Previous examination of transfusion strategies for people hospitalised with heart attack have produced conflicting results.
While doctors thought giving more blood transfusions would increase the amount of oxygen for the heart and improve outcomes, it may also increase the risk of fluid overload and rare infections.
This uncertainty led to the Myocardial Ischemia and Transfusion (MINT) trial, in which participants were randomly allocated to a restrictive or a liberal transfusion strategy.
In the liberal transfusion strategy, red blood cells were transfused to maintain the haemoglobin at or above 10 g/dL through hospital discharge or 30 days. In the restrictive transfusion strategy, transfusion was permitted only when the haemoglobin concentration was less than 8 g/dL and strongly recommended when the haemoglobin concentration was less than 7 g/dL or for cardiac symptoms not controlled with medications.
The analysis found 295 (16.9%) of the 1,749 participants in the restrictive transfusion trial pool experienced a recurrent heart attack or death, compared to 255 (14.5%) among 1,755 participants in the liberal transfusion pool – although this difference was not statistically significant.
Cardiac death was more common in people treated with a restrictive transfusion strategy (5.5%) compared to death among those treated in the liberal strategy (3.2%).
Heart failure and other 30-day clinical outcomes were similar in both groups, suggesting there is no undue risk to more liberal transfusions.
Study author Dr Jeffrey Carson, provost and distinguished professor of medicine at Rutgers Robert Wood Johnson Medical School, said: “The study results require a nuanced interpretation. While the trial did not produce a statistically significant difference between the two transfusion strategies for the primary outcome, the results suggest the possibility of liberal transfusion benefits without undue risk.
“The MINT results suggest a liberal transfusion strategy may be the most prudent approach for patients with heart attack and anaemia.”
The randomised controlled trial enrolled 3,506 participants – 45% women and 55% men – from 144 hospitals in the USA, Canada, France, Brazil, New Zealand and Australia between April 2017 and April 2023.
All participants, whose average age was 72 years, had heart attack and haemoglobin concentration levels less than 10 g/dL, compared to normal haemoglobin concentration of 12-13 g/dL.
Many also had other health conditions, including a history of heart attack (33%), heart failure (30%) diabetes (54%) and kidney disease (46%).
The primary trial endpoint was the composite of all-cause death and recurrent heart attack through 30 days following trial randomisation.
Dr Carson said the results should be interpreted with caution because the analyses were not adjusted for multiple statistical tests.
Other limitations include that treating clinicians knew which strategy participants were assigned to, and not all participants were discharged with haemoglobin concentration levels greater than 10 g/dL in the liberal transfusion group. This was often due to clinical discretion, such as concerns about fluid overload and timing of hospital discharge.
“Future research is needed to further resolve the controversy around transfusion decisions for people with anaemia and heart attack,” added Dr Carson.
Carson JL, Brooks MM, Hébert PC, Goodman SG, Bertolet M, Glynn SA, Chaitman BR, Simon R, Lopes RD, Goldsweig AM, DeFilippis AP, Abbott JD, Potter BJ, Carrier FM, Rao SV, Cooper HA, Ghafghazi S, Fergusson DA, Kostis WJ, Noveck H, Kim S, Tessalee M, Ducrocq G, Gabriel Melo de Barros e Silva P, Triulzi DJ, Alsweiler C, Menegus MA, Neary JD, Uhl L, Strom JB, Fordyce CB, Ferrari E, Silvain J, Wood FO, Daneault B, Polonsky TS, Senaratne M, Puymirat E, Bouleti C, Lattuca B, White HD, Kelsey SF, Steg PG, and Alexander JH for the MINT Investigators. (2023) “Restrictive or Liberal Transfusion Strategy in Myocardial Infarction and Anaemia.” NEJM, doi: 10.1056/NEJMoa2307983
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