Blood Transfusions in Patients Undergoing PCI Linked With Adverse CVD Outcomes

February 26, 2014

DURHAM, NC – A nationwide analysis of PCI suggests there is wide variability in the practice of blood transfusions and that patients who received blood transfusions fared significantly worse following PCI than those who did not receive them[1].

For patients undergoing PCI who received a blood transfusion, there was a significantly increased risk of MI, stroke, and in-hospital death, regardless of bleeding complications.

"When we looked at the outcomes, it turns out that blood transfusion, whether the patient bleeds or not, is associated with worse cardiovascular outcomes," lead investigator Dr Matthew Sherwood (Duke Clinical Research Institute, Durham, NC) told heartwire . "Despite the observational nature of the study, which is confounded by many things even though we attempted to adjust for these with a propensity-weighted analysis, we found that a bleeding event really didn't matter for the outcome. It was based upon transfusion."

Published in the February 26, 2014 issue of the Journal of the American Medical Association, the study showed the overall transfusion rate was 2.14% among 2.2 million patients who underwent PCI between 2009 and 2013 in the CathPCI Registry. Sherwood said there is a lack of definitive evidence on the risks and/or benefits of blood transfusion in the setting of acute coronary syndrome (ACS), and as a result, most physicians tend to adopt hospital practices. In their analysis, the risk-standardized rate of transfusion in PCI patients treated at the 1485 centers ranged from 0.3% to 9.3%.

Just over 96% of hospitals gave blood transfusions to less than 5% of their patients.

"We don't have a lot of randomized clinical trial evidence about transfusion strategies in PCI patients," said Sherwood. "Our observational research, though confounded, does point to the need for more data, specifically more randomized data to answer the question."

Recently, the American Association of Blood Banks (AABB) published new clinical guidelines, but these new guidelines were unable to address hospitalized, hemodynamically stable ACS patients, given the low-quality evidence available.

Transfusion, Not Bleeding, Ups the Post-PCI Risk

In the CathPCI Registry, after adjustment for multiple variables, receipt of blood was associated with significantly increased risk of MI, stroke, or in-hospital death. In the overall population, transfusion was associated with a more than 3.5-fold increased risk of the combined cardiovascular end point, and this increased risk was observed in patients with bleeding (odds ratio 1.16; 95% CI 1.11–1.22) and those without bleeding (OR 3.66; 95% CI 3.63–3.69). As individual end points, MI, stroke, and in-hospital death were all significantly increased in the overall population, irrespective of bleeding complications.

Given the absence of guideline recommendations for blood transfusions in PCI patients, Sherwood said their center tends to treat patients conservatively.

If the patient has a hemoglobin level <8 g/dL, they consider transfusion. If the patient is showing signs of anemia with a hemoglobin level <8 g/dL, a blood transfusion is also considered. Patients with anemia fare worse than patients without anemia, said Sherwood, as anemia is a risk factor known to exacerbate myocardial ischemia. Also, if the patient has a clinical syndrome, such as a retroperitoneal bleed or large hematoma in addition to a hemoglobin level <8 g/dL, that is another reason to transfuse.

"What we suggest is a conservative strategy with transfusion, and in PCI our goal would be to use bleeding-avoidance strategies so that we can minimize bleeding events and minimize physicians wanting to transfuse," Sherwood told heartwire . "Physicians are much more likely to transfuse a patient who is having a bleeding event."

At present, though, "we just don't know which type of patient transfusion would help and which patient it would harm," he added.

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