Giving blood transfusions to patients with acute heart problems nearly triples the risk they will die or suffer a heart attack within a month, a study said Tuesday.
The reason is not entirely clear, but researchers believe the blood used in the increasingly common procedure is often depleted of substances such as nitrous oxide that help deliver oxygen to the body’s tissues.
Transfused blood also may increase inflammation and further constrict blocked arteries and make the heart pump harder.
Overall, the analysis of three studies with more than 24,000 participants found 29 percent of the heart patients who got a transfusion died or had another heart attack within 30 days, compared to 10 percent of heart patients who did not get a transfusion.
The risk of dying was 8 percent among transfused patients, versus 3 percent for those who were not.
Transfusions are given to patients who have anemia because of bleeding or a deficiency of oxygen-carrying red blood cells.
In the United States, some 12 million units of blood are transfused into 3.5 million patients annually. The procedure has become more common among heart patients with the introduction of blood thinners to deter clots and more invasive procedures to unclog arteries.
The report does not call for an end to transfusions for heart patients. Instead, study author Dr. Sunil Rao of the Duke Clinical Research Institute in Durham, North Carolina, urged greater caution when deciding whether to transfuse anemic patients and suggested another study to determine the best approach.
“Blood transfusion may, at best, be neutral with respect to survival or, at worst, be associated with either decreased survival or worsening cardiac function,” based on previous studies, said the report published in this week’s Journal of the American Medical Association.
“(Our study) should not be considered as evidence to change practice; rather, it should be considered as evidence that caution is warranted when making transfusion decisions.”