Six-month outcomes after restrictive or liberal transfusion for cardiac surgery.

In this follow-up article to the TRICS III trial, the authors report the clinical outcomes of moderate- to high-risk patients undergoing cardiac surgery with cardiopulmonary bypass at 6 months after the operation.

The authors report on the original primary outcomes (death from any cause, myocardial infarction, stroke or renal failure with dialysis) and on secondary outcomes that include the primary outcomes, emergency department visit, hospital readmission or coronary revascularization within 6 months of the index surgery.

They conclude that a restrictive red blood cell transfusion strategy (transfusion if Hb < 7.5 g/dL intra- and postoperatively) is noninferior to a liberal transfusion strategy (transfusion if Hb < 9.5 g/dL intraoperatively and < 8.5 g/dL postoperatively) for all outcomes. The results of this long-term follow-up are interesting for several reasons. First, the study was large (more than 5000 patients), well conducted and independently funded (Canadian Institutes of Health Research). Thus, the results are highly credible. Second, since the publication of the TITRe2 study in which mortality at 90 days was increased (P = 0.045) in the restrictive transfusion group, the long-term effects of a restrictive threshold were unclear. Now we have a much better idea, at least in this patient population, of the (absence of) long-term effects of a restrictive transfusion strategy.

Finally, it is interesting to note that age may interact with transfusion strategy: the restrictive transfusion strategy was associated with a lower risk of primary composite outcome in patients 75 years of age or older. Conversely, a liberal transfusion strategy was associated with a lower risk of primary composite outcome in patients younger than 75 years of age. These results are counter-intuitive, contradict the findings of the original TRICC trial published in 1999 and require further investigation.

– Jean-François Hardy