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Limiting red-cell transfusion during heart surgery is an effective strategy that can save surgical departments valuable blood products without increasing risk for patients.

That finding emerged from the 5,000-patient TRICS III randomized trial, which was reported at American Heart Association meeting and simultaneously published online by .

Only if hemoglobin concentrations fell under 7.5 g/dL did patients get intraoperative and postoperative transfusion in a restrictive strategy by C. David Mazer, MD, of St. Michael's Hospital in Toronto, and colleagues. This way, red-cell transfusion was given 52.3% of the time versus 72.6% with a more liberal transfusion strategy (OR 0.41, 95% CI 0.37-0.47).

There was no difference in mortality between groups (3.0% versus 3.6%, OR 0.85, 95% CI 0.62-1.16).

Restricting transfusions was non-inferior to patients who were transfused more conservatively for the combined endpoint of all-cause death, MI, stroke,, or new-onset renal (11.4% for restrictive strategy versus 12.5% liberal strategy, OR 0.90, 95% CI 0.76-1.07, P<0.001 for noninferiority).

"The TRICS III trial provides compelling evidence that a restrictive transfusion strategy is as effective and safe as a liberal strategy in patients undergoing cardiac surgery," the trialists concluded.

Mazer estimated the cost savings within the study sample at several million U.S. dollars.

"These findings from TRICS III are great news for patients," commented Deepak Bhatt, MD, MPH, of Brigham and Women's Hospital in Boston. "The investigators have shown rather conclusively that for patients undergoing cardiac surgery, a restrictive transfusion strategy is at least as good as a more liberal one. That means less transfusions for patients, less of the potential risks associated with transfusions, less use of a precious resource, and also lower costs -- a win on all levels." Bhatt was not involved in the research.

For the purposes of this study, liberal red-cell transfusion meant that patients were transfused if hemoglobin dropped below 9.5 g/dL in the operating room/ICU or below 8.5 g/dL while in the non-ICU ward. Transfusion strategy was followed from the induction of anesthesia to either hospital discharge or 28 days after surgery, whichever came first.

Investigators randomized more than 5,000 patients who were undergoing cardiac surgery with cardiopulmonary bypass to one of the two transfusion strategies in this trial. Participants were enrolled across 73 sites worldwide.

For their analysis, the authors added 208 patients from their randomized TRICS II pilot study into the mix. They ended up with 5,092 patients in the modified intention-to-treat population (4,860 per-protocol, the basis for the primary outcome comparison). This was enough to give them 90% power to detect noninferiority with respect to the primary composite endpoint.

Patients went into cardiac surgery with a moderate-to-high mortality risk (a mean 7.8 points on EuroSCORE I). Mean age was 72 and 35.4% were women. Hemoglobin concentrations averaged 13.1 g/dL at baseline. Baseline characteristics were similar between the restrictive and liberal transfusion groups. Over half of patients got coronary artery bypass grafting with or without another concomitant procedure.

Of interest, subgroup analysis found that the restrictive strategy was associated with a lower composite outcome rate among those ages ≥75 (OR 0.70, 95% CI 0.54-0.89) but not the younger cohort (OR 1.17, 95% CI 0.91-1.50, P=0.004 for interaction).

While hypothesis-generating, this finding at least confirms that restrictive transfusion is safe in the elderly, according to the TRICS III researchers.

Mazer's group noted that they were unable to perform blinding for this trial, an important caveat. Their findings may not necessarily generalizable to low-risk patients, either.

Even so, Sellke called TRICS III an important trial, noting it was twice as large as the next largest trial.