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Blood for transfusion
MUNICH—A restrictive transfusion strategy during cardiovascular surgery will likely become the standard of care, according to an investigator from the TRICS III trial.
The study showed that a restrictive approach to transfusion did not increase the risk of poor outcomes at 6 months after cardiac surgery.
David Mazer, MD, of St. Michael’s Hospital, University of Toronto in Ontario, Canada, presented these findings at the 2018 ESC Congress. The results were published simultaneously in NEJM.
Dr. Mazer and his colleagues previously reported results from the TRICS III trial showing that 28-day outcomes were similar whether patients undergoing cardiac surgery were treated with a restrictive or a liberal transfusion strategy.
However, the team wanted to look into 6-month results to rule out latent problems, such as sequelae from perioperative organ hypoxia.
“Our research question was, ‘At what point does the risk of anemia, or the risk of a lower hemoglobin, outweigh the risk of transfusion?’” Dr. Mazer said. “We wanted to know whether it is safe to let your hemoglobin go to a lower level before you transfuse. The answer is yes. It’ll save blood, make blood more available, reduce costs of transfusion, and result in similar or better outcomes.”
Patients
The trial included 2317 patients who were randomized to a restrictive transfusion strategy, which meant they received red cell transfusions if their hemoglobin concentrations fell below 7.5 g/dL intraoperatively or postoperatively.
Another 2347 patients were randomized to the liberal approach, which meant they received transfusions if their hemoglobin fell below 9.5 g/dL in the operating room and intensive care unit (ICU) and below 8.5 g/dL outside the ICU.
Baseline characteristics were well balanced between the arms. Patients were a mean of 72 years old, and 35% were female. The majority of patients in both arms underwent coronary artery bypass surgery, valve surgery, or both. Heart transplants were excluded.
Results
At 6 months, 17.4% of patients in the restrictive arm and 17.1% in the liberal arm met the primary composite outcome of death from any cause, myocardial infarction, stroke, or new-onset renal failure with dialysis (P=0.006 for noninferiority).
Unexpectedly, patients age 75 and older had a lower risk of the primary outcome with the restrictive strategy, while the liberal strategy was associated with lower risk in younger patients.
For all age groups, there were no significant differences between the treatment arms for the individual components of the primary composite outcome or for secondary outcomes.
The mortality rate was 6.2% in the restrictive arm and 6.4% in the liberal arm. The rate of myocardial infarction was 7.3% in both arms.
The rate of stroke was 4% in the restrictive arm and 3.3% in the liberal arm. The incidence of new-onset renal failure with dialysis was 3.9% and 4.2%, respectively.
The secondary composite outcome included the components of the primary outcome plus hospital readmissions, emergency department visits, and coronary revascularization. This outcome occurred in 43.8% of patients in the restrictive arm and 42.8% in the liberal arm.
The incidence of hospital readmissions/emergency visits was 35.5% in the restrictive arm and 33.6% in the liberal arm. The incidence of coronary revascularization was 0.7% and 0.9%, respectively.
The investigators also found the restrictive transfusion strategy effectively saved blood. Just over half of patients (52.3%) in the restrictive arm and almost three-quarters (72.6%) of those in the liberal arm were transfused after randomization.
“This research has already started to change transfusion practice around the world,” Dr. Mazer said. “With this data at six months, we’ve proven the longer-term safety of restrictive therapy. This approach has already been adopted into guidelines and will likely become the standard of care worldwide.”
This study was funded by the Canadian Institutes of Health Research, Canadian Blood Services, the National Health and Medical Research Council in Australia, and the Health Research Council of New Zealand. Dr. Mazer had no relevant disclosures.