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Implementing a stricter limit on red blood cell transfusion did not hurt heart attack patients with anemia and was in fact associated with signals of improved safety, according to the .

The strategy of withholding transfusion unless hemoglobin dropped to 8 g/dL was noninferior to the liberal strategy of transfusing as soon as hemoglobin dropped to 10 g/dL in terms of the 30-day composite outcome of all-cause death, MI, stroke, and emergency revascularization prompted by myocardial ischemia (11.0% vs 14.0%, difference -3.0%, 95% CI -8.4% to +2.4%).

A cost-effectiveness analysis determined that the restrictive transfusion strategy was dominant at 30 days, given an 84% probability of cost savings while improving outcomes over the more liberal option, reported Philippe Gabriel Steg, MD, of Hôpital Bichat, Paris.

Previous trials of restrictive versus liberal transfusion in cardiac surgery had excluded patients with acute MI, Steg noted during his presentation at this year's virtual conference of the (ESC).

"Blood is a precious resource, and transfusion is costly, logistically cumbersome, and has side effects. The REALITY trial supports the use of a restrictive strategy for blood transfusion in MI patients with anemia," Steg said in an ESC press release.

In the trial, patients randomized to the restrictive strategy had a lower infection risk (0% vs 1.5%, P=0.03) and risk of acute lung injury (0.3% vs 2.2%, P=0.03). Other safety endpoints occurred at statistically similar rates between study arms.

"This is an important and very clinically relevant study. The findings are certainly in keeping with our TRICS III study of restrictive versus liberal transfusion in high risk patients undergoing cardiac surgery, many of whom had coronary revascularization procedures," said C. David Mazer, MD, of St. Michael's Hospital in Toronto, Ontario, who was not involved with REALITY.

Likewise, Bob Harrington, MD, of Stanford University in California, and immediate past president of the American Heart Association, said he was "not surprised" by the promising results from Steg's team.

"Most of us in acute cardiac care have looked at the prior trials and of the observational studies that have suggested cardiac risk with transfusion to push towards more restrictive transfusion policies. These data are certainly supportive of that approach," Harrington said.

The REALITY study was conducted at 35 hospitals in France and Spain.

Investigators had included 668 acute MI patients with anemia at admission. The average hemoglobin level at admission was 10 g/dL for both restrictive and liberal transfusion arms. The two groups had hemoglobin fall further, to 9 g/dL, at randomization.

The restrictive transfusion strategy had fewer patients receive any red blood pack cells (35.7% vs 86.7%, P<0.0001).

Patients in this arm reached lower minimum hemoglobin levels during their hospital stay (8.3 vs 8.8 g/dL, P<0.0001) and tended to have lower hemoglobin at discharge (9.7 vs 11.1 g/dL, P<0.0001).

The relatively small sample precluded study authors from analyzing the effects of restrictive transfusion according to age, Steg acknowledged during an ESC press conference.

A numerical increase in acute renal failure with this strategy (9.7% vs 7.1%) also deserves a closer look, according to Harrington.

"There still is significant variability in transfusion practice for patients with acute coronary ischemia, in part because of the lack of robust data and concern about the risks of both anemia and transfusion," said Mazer.

"Transfusion decisions should always be based on the decision of when the risks of anemia outweigh the risks of transfusion, and large well-conducted trials like REALITY, TRICS III, and the ongoing, similar and much larger MINT trial should help optimize practice and improve outcomes," he noted.

MINT is an with an estimated enrollment of 3,500 patients that is expected to answer the question of whether the restrictive transfusion strategy is superior to a looser one.

Notably, Public Citizen criticized MINT in 2017 because of perceived ethics violations.

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