The authors studied a database of 1,915 patients who underwent isolated first time myocardial revascularization between 1994 and 1997 and found that blood transfusions during or after coronary artery bypass operations were associated with increased long-term mortality (risk ratio = 1.7; 95% confidence interval = 1.4 to 2.0).

This retrospective database analysis is important and supports the concept that blood transfusions may not be as effective and safe as we have been taught traditionally.

However, as acknowledged by the authors, such analyses suffer from numerous and inherent limitations and do not support a cause to effect relationship. Only prospective randomized studies will be capable of determining with any degree of certainty if a restrictive transfusion strategy is preferable after cardiac operations.

Several questions remain unanswered: would the use of leukodepleted blood products have resulted in the same outcomes? Is the effect similar in other types of cardiac operations? What was the effect of anemia per se, of the age of transfused blood, of the number of units transfused?

Nonetheless, the association between transfusion and poorer long-term outcome is troubling and should raise questions in every clinician’s mind. All cardiovascular anesthesiologists must read this article and think again before transfusing patients undergoing myocardial revascularization.

– Jean-Franois Hardy