Durham, NC - The days of maintaining hematocrit levels at 30% in ischemic heart disease may be gone. Researchers say that levels in stable patients can potentially plunge lower without adverse events. "Don't treat the number, treat the patient," lead investigator Dr Sunil Rao (Duke Clinical Research Institute, Durham, NC) told heartwire. "Our findings suggest that there is good reason to think twice before giving blood," he said, explaining that blood transfusions can potentially do more harm than good.

Dr Sunil Rao

In a paper published in the October 6, 2004 issue of the Journal of the American Medical Association, Rao and colleagues point out that although transfusing blood to anemic patients with ischemic heart disease may theoretically increase oxygen delivery and improve outcomes, there is no definitive evidence to support such a practice.1 "Some studies actually indicate no increase in tissue oxygenation with blood transfusion," they write.

In the present analysis, the researchers sought to determine the association between blood transfusion and mortality among patients with acute coronary syndromes who develop bleeding, anemia, or both during hospitalization.

They looked at 24112 participants in three large international trials of patients with acute coronary syndromes. These included:

The Global Use of Strategies to Open Occluded Coronary Arteries (GUSTO) IIb.

Platelet Glycoprotein IIb/IIIa in Unstable Angina: Receptor Suppression Using Integrilin Therapy (PURSUIT).

Platelet IIb/IIIa Antagonism for the Reduction of Acute Coronary Syndrome Events in a Global Organization Network (PARAGON) B.

Patients were grouped according to whether they received a blood transfusion during hospitalization. The main outcome measure was 30-day mortality.

Rao and colleagues found that 10% of the patients had at least one blood transfusion. Those who had a transfusion were older and had more comorbid illness at presentation. They also had a significantly higher unadjusted rate of 30-day death and myocardial infarction compared with patients who did not have a transfusion.

Using Cox proportional hazards modeling that incorporated transfusion as a time-dependent covariate, the researchers found that transfusion was associated with an increased hazard for 30-day death (adjusted hazard ratio 3.94, 95% CI, 3.26-4.75) and 30-day death and myocardial infarction (HR 2.92, 95% CI, 2.55-3.35).

In a landmark analysis that included procedures and bleeding events, transfusion was associated with a trend toward increased mortality. The predicted probability of 30-day death was higher with transfusion at nadir hematocrit values above 25%.

"The results of our study show that blood transfusion in the setting of anemia during hospitalization for acute coronary syndromes is associated with increased 30-day mortality," Rao and colleagues write. "This association persisted across the three different analytical methods we used."

In an interview with heartwire, Rao explained that blood that is stored and later transfused is depleted of nitric oxide. "Instead of the desired vasodilation, you may actually get vasoconstriction," he said.

The research team calls for a randomized trial to guide clinical practice, but until then, they caution against the routine use of blood transfusion to maintain hematocrit levels in stable patients with ischemic heart disease.