Blood transfusions are frequently given to patients to treat low hemoglobin levels in the setting of non-ST-segment elevation acute coronary syndromes, percutaneous coronary intervention, and coronary artery bypass grafting. Evidence suggests that blood transfusion therapy in the setting of ischemic heart disease is associated with an increased risk for morbidity and mortality; however, there are no randomized clinical trials concerning transfusion strategies in ischemic heart disease. The evidence to date is observational and subject to confounding influences. This lack of definitive data has led to wide variations in transfusion practice in both the US and the international medical community. The purpose of this article is to examine the current literature concerning the transfusion practice of whole or packed red blood cells in the US and internationally in patients with ischemic heart disease. We propose that a prospective, randomized, controlled trial of transfusion strategies in ischemic heart disease is needed to determine the role of transfusion in this patient population.
Current evidence-based therapies for ischemic heart disease include antithrombotic and antiplatelet medications that reduce the risk for ischemic outcomes such as myocardial infarction and stroke.1 Given their mechanism of action, bleeding is a risk with these agents, especially when combined with invasive procedures.2 In addition to overt bleeding, clinical trials of antithrombotic strategies suggest that these patients also are subject to acute anemia (manifested as decreases in hemoglobin values during hospitalization) and blood transfusion. Several studies have shown a powerful association between anemia and adverse outcomes among patients with non-ST-segment elevation acute coronary syndromes (NSTE ACS).3 A common strategy to deal with both bleeding and anemia in the ACS population is blood transfusion. Ostensibly given to increase hemoglobin levels and improve oxygen delivery to ischemic myocardial tissue, clinical and laboratory evidence suggests that blood transfusion not only does not improve oxygenation but also is associated with worse clinical outcomes. It is important to note that these data analyses are observational, retrospective, and subject to confounding influences.4 Indeed, there has never been a randomized trial of transfusion strategies in ischemic heart disease. This lack of definitive data has resulted in wide variation in transfusion practice. The purpose of this article is to summarize the current literature on the association between blood transfusion and outcomes and to review variations in transfusion practice in patients with ischemic heart disease.
Association Between Blood Transfusion and Outcomes
Recent retrospective studies have investigated the association between blood transfusion and outcomes in patients with NSTE ACS, percutaneous coronary intervention (PCI), and coronary artery bypass grafting (CABG). Rao et al.5 examined 24,000 patients with NSTE ACS and found an association between blood transfusion and increased 30-day mortality (adjusted hazard ratio 3.94, 95% confidence interval [CI] 3.26–4.75). Similarly, Wu et al.6 found an association between transfusion and increased mortality among elderly Medicare beneficiaries with acute MI when transfusion was given for an admission hematocrit level above 33%. Mortality was lower with transfusion among patients with an admission hematocrit level <30%. Yang et al.7 examined the Can Rapid Risk Stratification of Unstable Angina Patients Suppress Adverse Outcomes with Early Implementation of the American College of Cardiology/American Heart Association Guidelines (CRUSADE) National Quality Improvement Initiative registry of ACS patients and found an association between transfusion and increased in-hospital mortality (adjusted odds ratio 1.67, 95% CI 1.48–1.88).
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- Rao SV, Eikelboom JA, Granger CB, et al., Bleeding and blood transfusion issues in patients with non-ST-segment elevation acute coronary syndromes, Eur Heart J, 2007;28(10):1193–1204.
- Sabatine MS, Morrow DA, Giugliano RP, et al., Association of hemoglobin levels with clinical outcomes in acute coronary syndromes, Circulation, 2005;111:2042–9.
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- Rao SV, Jollis JG, Harrington RA, et al., Relationship of blood transfusion and clinical outcomes in patients with acute coronary syndromes, JAMA, 2004;292:1555–62.
- Wu WC, Rathore SS, Wang Y,et al., Blood transfusion in elderly patients with acute myocardial infarction, N Engl J Med, 2001;345:1230–36.
- Yang X, Alexander KP, Chen AY, et al., CRUSADE Investigators: The implications of blood transfusions for patients with non-ST-segment elevation acute coronary syndromes: Results from the CRUSADE National Quality Improvement Initiative, J Am Coll Cardiol, 2005;46:1490–95.
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- Murphy GJ, Reeves BC, Rogers CA, et al., Increased Mortality, Postoperative Morbidity, and Cost After Red Blood Cell Transfusion in Patients Having Cardiac Surgery, Circulation, 2007;116;2544–52.
- Koch CG, Li L, Sessler DI, et al., Duration of red-cell storage and complications after cardiac surgery, N Engl J Med, 2008;358(12):1229–39.
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- Moscucci M, Fox KA, Cannon CP, et al., Predictors of major bleeding in acute coronary syndromes: the Global Registry of Acute Coronary Events (GRACE), Eur Heart J, 2003;24: 1815–23.
- Berkowitz SD, Stinnett S, Cohen M, et al., Prospective comparison of hemorrhagic complications after treatment with enoxaparin versus unfractionated heparin for unstable angina pectoris or non-ST-segment elevation acute myocardial infarction, Am J Cardiol, 2001;88:1230–34.
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- Alexander KP, Chen AY, Roe MT, et al., CRUSADE Investigators. Excess dosing of antiplatelet and antithrombin agents in the treatment of non-ST-segment elevation acute coronary syndromes, JAMA, 2005;294:3108–16.
- Gilchrist IC, Berkowitz SD, Thompson TD, et al., Heparin dosing and outcome in acute coronary syndromes: the GUSTO-IIb experience. Global use of strategies to open occluded coronary arteries, Am Heart J, 2002;144:73–80.
- Eikelboom JW, Mehta SR, Anand SS, et al., Adverse impact of bleeding on prognosis in patients with acute coronary syndromes, Circulation, 2006;114:774–82.
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