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Blood Transfusion in Patients With Acute Coronary Syndrome

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Blood Transfusion in Patients With Acute Coronary Syndrome

Friday, February 18th, 2005
Author: SABM Staff

Blood Transfusion in Patients With Acute Coronary Syndrome

In 1999, the landmark TRICC trial, a large prospective randomized trial of 838 critically ill patients, found that a restrictive transfusion strategy was at least as good as, and possibly superior to, a liberal strategy (Hebert et al., N Engl J Med 1999;340:409-17). In a subgroup analysis of patients with cardiovascular disease, no statistically significant difference in clinical outcomes was observed between the two groups; only in patients with severe ischemic heart was the restrictive strategy associated with lower absolute survival rates, although the difference was not significant. The authors concluded that “a restrictive red blood cell transfusion strategy generally appears to be safe in most critically ill patients with cardiovascular disease, with the possible exception of patients with acute myocardial infarcts and unstable angina� (Hebert PC et al., Crit Care Med 2001;29:227-34).

In a subsequent observational study involving 78,974 elderly patients admitted to hospital with myocardial infarction, Dr. Wu and colleagues from the Yale University School of Medicine reported an association between transfusion and decreased 30-day mortality among patients with an admission hematocrit of 33% or lower (Wu et al., N Engl J Med 2001;345:1230-6). More recently, Dr. Rao and colleagues from the Duke Clinical Research Institute analyzed data on 24,112 patients with acute coronary syndromes enrolled in 3 international randomized controlled trials of anticoagulation and antiplatelet strategies, and found that even after adjustment for baseline characteristics, bleeding and transfusion propensity, and nadir hematocrit, blood transfusion was associated with a hazard ratio for 30-day death of 3.94 (95% CI, 3.26-4.75) (Rao et al., JAMA 2004;292:1555-62).

In a letter to the editor published in the February 9, 2005, issue of JAMA, Mr. Rathore and Drs. Radford and Krumholz, who participated in the Wu study, say they are “concerned by the conclusion of the study by Dr. Rao and colleagues that use of blood transfusion in patients with acute coronary syndromes is associated with higher mortality� (Rathore et al., JAMA 2005;293:673). “The finding that transfusion is associated with a nearly 4-fold increased hazard of 30-day mortality in this study is even more concerning,� they add. “This risk,� they point out, is much higher than any previously reported transfusion-associated harm; the magnitude exceeds the risks of encainide or flecainide for arrhythmia suppression after myocardial infarction.� “We believe,� the authors conclude, “that the preponderance of available data suggest that transfusion remains a reasonable therapy in patients with acute coronary syndromes with hematocrit levels below 30%.�

In their reply to the above-mentioned letter, Drs. Rao, Harrington, Califf, and Stamler note that both observational studies found that transfusion at a hematocrit of 36% or more is associated with increased mortality (Rao et al., JAMA 2005;293:674-5). However, whereas the study by Wu et al. “suggests that transfusion for a hematocrit below 30% is associated with decreased mortality,� the study by Rao et al. “could not identify a hematocrit threshold below which transfusion was beneficial� but “found that transfusion for a hematocrit greater than 25% was associated with harm.� Transfusion practice guidelines, they note, do not recommend transfusion for asymptomatic patients with anemia regardless of their hematocrit. Currently available evidence, they argue, does not support aggressive transfusion among patients who are hemodynamically stable. Until large, well-designed randomized controlled trials settle the controversial issue of transfusion thresholds in patients with cardiovascular disease, the authors recommend that clinicians “avoid blood transfusion to maintain arbitrary hematocrit levels in patients who are otherwise stable.�

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Mr. Jan B. Wade
Blood Management Consultant
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