Clinical Question: Does a blood transfusion in anemic patients with acute coronary syndrome improve survival?

Setting: Inpatient (any location) with outpatient follow-up

Study Design: Cohort (prospective)

Synopsis: Investigators analyzed data from 24,112 patients enrolled in three large international trials evaluating various anti-thrombotic regimens in patients with acute coronary syndromes. Analysis was limited to patients with complete data on transfusion and bleeding occurrence. All end points were evaluated by persons who were blinded to treatment group assignment and who were unaware of whether patients received blood transfusions. Because blood transfusion was left to the discretion of the treating physician, associations between transfusion and primary and secondary end points were evaluated using multiple logistic regression to identify independent variables and control for confounding factors.

A total of 2,401 patients (10 percent) underwent at least one blood transfusion during their hospitalization. Transfusion was related independently to an increased risk of death at 30 days (hazard ratio = 3.94; 95 percent confidence interval, 3.26 to 4.75). The predicted probability of death was higher when a transfusion was performed for hematocrit values greater than 25 percent, with no benefit or risk detected for transfusions given for values lower than 25 percent.

A previous trial (Wu WC, et al. Blood transfusion in elderly patients with acute myocardial infarction. N Engl J Med October 25, 2001;345:1230–6) showed a benefit of selective transfusion in elderly patients hospitalized with acute coronary syndrome and a hematocrit less than 33 percent on admission (i.e., not acutely developing during hospitalization).

Bottom Line: Blood transfusion in otherwise stable patients with acute coronary syndrome who develop anemia during hospitalization may increase mortality risk, especially if the hematocrit level is higher than 25 percent. (Level of Evidence: 2b)