ANAHEIM, CALIF. (FRONTLINE MEDICAL NEWS) – Waiting to transfuse heart surgery patients until their hemoglobin drops below 7.5 g/dL is just as safe as transfusing them when their hemoglobin drops below 9.5 g/dL, and it saves a lot of blood, according to the TRICS III randomized, noninferiority trial of nearly 5,000 patients undergoing cardiac surgery with cardiopulmonary bypass.

Cardiac surgeons have been moving to more restrictive transfusion policies following reports of worse postoperative survival when patients are transfused. However, there are concerns about safety and uncertainty over whether it’s the transfusions themselves that are problematic or whether transfused patients do worse because they are sicker to begin with. The Transfusion Requirements in Cardiac Surgery (TRICS) III trial removes some of the doubt: “A restrictive transfusion strategy is as effective and safe as a liberal strategy in patients undergoing cardiac surgery,” said lead investigator C. David Mazer, MD , a professor in the department of anesthesia at the University of Toronto.

The team randomized 2,430 cardiac surgery patients to receive red cell transfusions if hemoglobin concentrations fell below 7.5 g/dL intraoperatively or postoperatively. Another 2,430 were randomized to a more liberal approach, with transfusions being performed below 9.5 g/dL in the operating room and ICU and below 8.5 g/dL outside of the ICU. The arms were well matched and had a mean score of 8 on the 47-point European System for Cardiac Operative Risk Evaluation I score, which is an estimate of mortality risk. Participants were followed until hospital discharge or postop day 28, whichever came first.

Overall, 11.4% in the restrictive-threshold group and 12.5% in the liberal-threshold group met the study’s composite primary outcome of death from any cause, MI, stroke, and new-onset renal failure with dialysis (P less than .001 for noninferiority). There were no statistically significant between-group differences in the individual components of the composite outcome. Mortality was 3% in the restrictive group and 3.6% in the liberal group, a 15% reduction for the restrictive group.

About 52% of the patients in the restrictive arm, compared with 72.6% in the liberal arm, were transfused. When transfused, patients in the restrictive arm received a median of 2 units of red cells; liberal-arm patients received a median of 3 units. The overall cost difference was roughly $3 million, Dr. Mazer said at the American Heart Association scientific sessions.

There were no statistically significant differences in secondary outcomes. Restrictive patients were on mechanical ventilation for a median of 0.38 days and in the ICU for a median of 2.1 days; patients in the liberal arm were ventilated for a median of 0.36 days and in the ICU for a median of 1.9 days. The median hospital stay was 8 days in both groups.

Unexpectedly, patients 75 years and older did better with the restrictive transfusion strategy, with a 30% lower risk of the composite outcome. “Many people think the older you are, the higher your hemoglobin should be, and the more liberal you should be with transfusions. We didn’t find that. [It] challenges current beliefs and may be considered to be hypothesis generating; at a minimum, it highlights that a restrictive transfusion strategy appears to be safe in elderly patients,” Dr. Mazer said.

The participants were a mean of 72 years old, and 35% were women. The majority in both arms underwent coronary artery bypass surgery, valve surgery, or both. Heart transplants were excluded from the study. The trial was conducted in 19 countries, including China and India, but “the results were remarkably consistent independent of where the sites were,” he said.

Results of the TRICS III trial were published simultaneously with Dr. Mazer’s presentation (N Engl J Med. 2017 Nov 12. doi: 10.1056/NEJMoa1711818 ).

The trial was funded by the Canadian Institutes of Health Research, among others. Dr. Mazer reported personal fees from Amgen, Boehringer Ingelheim, Octapharma, and Pharmascience, as well as grants and personal fees from Fresenius Kabi.