PhotoA new meta-analysis of 10 studies finds a higher mortality rate among heart attack patients who get blood transfusions, but medical authorities cautioned that more research was needed.

In the meta-analysis published Online First by Archives of Internal Medicine, a JAMA Network publication, Saurav Chatterjee, M.D., of Brown University and Providence Veterans Affairs Medical Center, Rhode Island, and colleagues conducted a review of studies published between January 1966 and March 2012.

Ten studies, including 203,665 participants, were selected for analysis. Only one study was a randomized trial, while the others were observational studies.

“Analyses of blood transfusion in myocardial infarction revealed increased all-cause mortality associated with a strategy of blood transfusion vs. no blood transfusion during myocardial infarction (18.2 percent vs. 10.2 percent), with a weighted absolute risk increase of 12 percent,” the authors wrote. 

Blood transfusion also appeared to be associated with a higher risk for subsequent myocardial infarction, according to the study results.

Transfusions are sometimes needed because therapeutic measures including anticoagulation and antiplatelet drugs may increase the risk for bleeding, which can lead to patients developing anemia during their hospital stay and requiring blood transfusion, according to the study background.

“In conclusion, this meta-analysis provides evidence that rates of all-cause mortality and subsequent myocardial infarction are significantly higher in patients with acute myocardial infarction receiving blood transfusion. Additional outcomes data are needed from randomized clinical trials that investigate important outcomes with adequate sample size and with low risk for bias,” the authors concluded.

Skeptics unconvinced

But not everyone found the evidence convincing.

“Do blood transfusions kill more patients with an acute myocardial infarction than anemia? Chatterjee and colleagues would have you believe that they do. We remain unconvinced,” said Jeffrey L. Carson, M.D., of the University of Medicine and Dentistry of New Jersey, New Brunswick, and Paul C. Hébert, M.D., of the Ottawa Hospital Research Institute, Canada, in an accompanying commentary. 

“What might we take away from this systematic review? The authors remind us that patients with an acute myocardial infarction are often anemic and receive red blood cell transfusion. However, because of its many limitations, as physicians, we should not use the results of this review to justify or limit the use of red blood cells,” they continue.

“For researchers and decision makers, we can now appreciate how little reliable information is available to inform clinical and policy decisions involving red blood cell transfusions in patients with acute coronary syndrome. Given that real risks and potential benefits exist as to how we choose to use the valuable resource of blood transfusion, we believe that high-quality research is long overdue,” they conclude.

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