Bypass Surgery Riskier for Anemic People
Death rate higher, solution uncertain
THURSDAY, May 16, 2002 (HealthDayNews) -- Bypass surgery patients who are anemic have an unusually high risk of dying, British cardiologists report, but it's not clear what can be done to improve their outcome.
Examining data on more than 2,000 bypass patients, doctors at the Imperial College School of Science, Technology and Medicine in London say that those with blood hemoglobin levels of less than 100 grams per liter -- a clear sign of anemia -- were five times more likely to die in the hospital than those with higher readings.
The overall death rate for the study group was 3.8 percent, or 78 deaths among the 2,059 patients. It was 17 percent, or 9 of 59 patients, for those with low hemoglobin levels.
And that higher death rate occurred even though the anemic patients were given blood transfusions to bring up their hemoglobin levels, says a report in the May 18 issue of The Lancet.
"We are in the process of changing our protocol for dealing with these patients," says Dr. Jens Peder Bagger, a consultant cardiologist and lead author of the journal report. "Maybe if we do a bit of work beforehand and find out why they do have anemia, we could improve the survival rate."
It is routine for bypass patients at Hammersmith Hospital, where the study was done, to be given transfusions if their hemoglobin level is low, but "our study shows it is not that simple," Bagger says. "We need to take time to evaluate these patients before surgery, because they may have other conditions that cause the anemia. It could reflect coronary heart disease or even cancer, which can cause low hemoglobin."
A similar observation has been made by an American group, says Dr. Irving L. Kron, who is chief of surgery at the University of Virginia Medical Center and a member of the American Heart Association surgical council. But the British method of giving transfusions may not be an answer, he says.
"We try not to give much blood during surgery," Kron says. "There are risks, such as hepatitis and AIDS, that are small but real, so we try our best not to transfuse. The question is whether this low hemoglobin level is a marker for other conditions."
Kron says his group encounters the issue more often than was reported by the British group. Perhaps a third of his bypass patients have low hemoglobin levels, he says.
Current practice, he adds, is to transfuse older anemic patients and those with other conditions that worsen their outlook, but not younger, less compromised patients.
But even the value of that practice needs to be tested, Kron says, adding, however, "I don't know if this report gives us the information needed to change our procedure."
"A study needs to be done in which you take two groups of people who are anemic, bring one up to normal and with the other do as you normally do to find out which one does better," he says.
Bagger says his group now is putting into place a procedure for routine testing of anemic bypass patients to see if their blood count reflects an underlying condition that requires special treatment. It will take some time to learn whether that procedure will save lives, he says, but it is necessary.
"We need a historical comparison to see whether it helps," Bagger says. "Nowadays we have excellent results with bypass patients in general. But we need to look at marginal patients, such as those with anemia, to try to improve those results."