Transfusion practice varies greatly across the US. A recent study by Sherwood, et al. further supports this find, specifically in a Percutaneous Coronary Intervention (PCI) setting. Transfusion in such an intervention remains controversial. On one hand, there seems to be a physiological reason supporting the decision to transfuse that is raising hemoglobin levels of anemic patients will increase oxygen delivery and reduce the risk of myocardial infarction (MI). However, recent evidence suggests that transfusion in the setting of PCI may be detrimental to the patient’s health.

In an attempt to identify RBC transfusion patterns among patients undergoing PCI, Sherwood and colleagues analyzed data from the CathPCI Registry of the American College of Cardiology Foundation and the Society for Cardiovascular Angiography and Interventions, the largest ongoing registry of PCI cases in the United States. The analysis covered 2,258,711 PCI visits from 1,967,218 patients in 1,431 hospitals from July 2009 to March 2013.1 Patients who underwent coronary artery bypass graft surgery and patients with missing data on bleeding events, transfusion, or complications were excluded from the study.

Overall the transfusion rate was 2.14%, however this rate varied by hospital and ranged from 0 to 13%.1 Approximately 96% of hospitals transfused less than 5% of PCI patients, and about 4% of hospitals transfused more than 5% of patients.1 The transfusion rate for non-bleeding patients increased when the post procedural hemoglobin level was 8 g/dL or lower.1 Sherwood and colleagues also categorized each hospital by transfusion rate as low (<1.78%), medium (1.78 to <2.79%), or high (≥2.79), and found that high-transfusing hospitals were less likely to be privately owned, less likely to be rural, and more likely to be a teaching hospital.1

While the work by Sherwood et al. does not determine the most appropriate transfusion trigger for a PCI setting, the remarkably high variation in transfusion rates show the lack of consensus regarding transfusion therapy in patients with acute coronary syndrome (ACS). In fact, very few clinical studies of transfusion in ACS patients are available, and the few that exist report conflicting results. The MINT trial found a significantly lower 30-day mortality rate in patients assigned to a transfusion trigger, as defined by hemoglobin value, of 10 g/dL compared to those assigned to a trigger of 8 g/dL, as well as insignificantly lower rates of MI and unscheduled revascularization.2 Contrary to these results, the CRIT trial compared the same transfusion triggers and found the more liberal transfusion trigger to be associated with a higher rate of death, MI, and heart failure.3 The FOCUS trail also compared transfusion triggers in patients with coronary artery disease recovering from hip arthroplasty and found no difference in outcomes, however this trial was likely underpowered and did not meet its predetermined sample size.4

Now added to the small list of studies on transfusion in ACS patients is the result found by Sherwood and colleagues that transfusion was associated with a higher risk for MI, stroke, and death, regardless of bleeding.1 This finding seems to refute the previously mentioned logic for transfusing anemic patients and may be a result of red blood cell storage lesions that impair oxygen delivery. The wide variation in transfusion rate of patients undergoing PCI, including some very aggressive transfusion practices, indicate the necessity for more randomized clinical trials to define appropriate transfusion practices in this particularly vulnerable patient population. With additional evidence, this group of patients will receive higher quality and standardized care in regards to transfusion therapy.

References

  1. Sherwood MW, Wang Y, Curtis JP, et al. Patterns and Outcomes of Red Blood Cell Transfusion in Patients Undergoing Percutaneous Coronary Intervention. JAMA 2014;311(8):836-843.
  1. Carson JL, Brooks MM, Abbott JD, et al. Liberal vs restrictive transfusion thresholds for patients with symptomatic coronary artery disease. Am Heart J. 2013;165(6):964-971.
  1. Cooper HA, Rao SV, GreenbergMD, et al. Conservative versus liberal red cell transfusion in acute myocardial infarction (the CRIT Randomized Pilot Study). Am J Cardiol. 2011;108(8):1108-1111.
  1. Carson JL, TerrinML, Noveck H, et al; FOCUS Investigators. Liberal or restrictive transfusion in high-risk patients after hip surgery. N Engl J Med. 2011;365(26):2453-2462.