Acute coronary syndrome, stable coronary artery disease, and congestive heart failure
Anemia is an independent predictor of major adverse cardiovascular events in patients with acute coronary syndrome.9 However, it remains controversial if transfusion has benefit or causes harm in patients with acute coronary syndrome. No randomized controlled trials have yet been published on this topic, and observational studies and subgroups from randomized controlled trials have yielded mixed results.
Similarly, there are no randomized controlled trials examining liberal versus restrictive transfusion goals for asymptomatic hospitalized patients with stable coronary artery disease (CAD). However, patients with CAD were included in the TRICC and FOCUS trials.3,8 Of patients enrolled in the TRICC trial, 26% had a primary or secondary diagnosis of cardiac disease; subgroup analysis found no significant differences in 30-day mortality between treatment groups, similar to that of the entire study population.3 In a subgroup analysis of patients with “cardiovascular disease” the FOCUS trial found no difference in outcomes between a restrictive and liberal transfusion strategy, although there was a marginally higher incidence of myocardial infarction in the restrictive arm in the entire study population.8
Although some studies have included patients with congestive heart failure (CHF) as a subgroup, these subgroups are often not powered to show clinically meaningful differences. The risk of volume overload is one explanation for why transfusions may be harmful for patients with CHF.
Based on these limited available data, the AABB guidelines recommend a “restrictive RBC transfusion threshold (hemoglobin level of 8 g/dL)” for patients “with preexisting cardiovascular disease,” without distinguishing among patients with acute coronary syndrome, stable CAD, and CHF, but adds that the “threshold of 7 g/dL is likely comparable with 8 g/dL, but randomized controlled trial evidence is not available for all patient categories.”1
Of note, certain patient populations, such as those with end-stage renal disease, oncology patients (especially those undergoing active chemotherapy), and those with comorbid conditions such as thrombocytopenia and coagulopathy are specifically excluded from the AABB guidelines. The reader is referred to guidelines from respective specialty societies for further guidance.
Back to our case
This 48-year-old man with cirrhosis and esophageal varices presenting with ongoing blood loss due to hematochezia and hematemesis with a hemoglobin of 7.8 g/dL should be transfused due to his active bleeding; his hemoglobin level should not be a determining factor under such circumstances. This distinction is one of the most fundamental in interpreting the guidelines, that is, patients with hemodynamic insult, symptoms, and/or ongoing bleeding should be evaluated clinically, independent of their hemoglobin level.
Bottom line
Although recent guidelines generally favor a more restrictive hemoglobin goal threshold, in the presence of active blood loss or hemodynamic instability, blood transfusion should be considered independent of the initial hemoglobin level.
Key Points
- The AABB guidelines recommend transfusing stable general medical inpatients to a hemoglobin level of 7 g/dL.
- For patients undergoing orthopedic surgery, cardiac surgery, and those with preexisting cardiovascular disease, a transfusion threshold of 8 g/dL is recommended.
- Patients with hemodynamic instability or active blood loss should be transfused based on clinical criteria, and not absolute hemoglobin levels.
- Patients with acute coronary syndrome, severe thrombocytopenia, and chronic transfusion–dependent anemia are excluded from these recommendations.
- Further studies are needed to further refine these recommendations to specific patient populations in maximizing the benefits and minimizing the risks of blood transfusions.
Quiz
In which of the following scenarios is RBC transfusion LEAST indicated?
- A. Active diverticular bleed, heart rate 125 beats/minute, blood pressure 85/65 mm HG, hemoglobin 10.5 g/dL
- B. Septic shock in the ICU, hemoglobin 6.7 g/dL
- C. Pulmonary embolism in the setting of stable coronary artery disease and hemoglobin 8.7 g/dL
- D. Lymphoma on chemotherapy, hemoglobin 7.5 g/d, patient becomes dizzy when standing
Answer: C – A hemoglobin transfusion goal of 8.0 g/dL is recommended for patients with cardiovascular disease. The patient in answer choice A has active blood loss, tachycardia, and hypotension, all pointing to the need for blood transfusion irrespective of an initial hemoglobin level greater than 8.0 g/dL. The patient in answer choice B has a hemoglobin level less than 7.0 g/dL, and the patient in choice D is symptomatic, possibly from anemia, as well as on chemotherapy, therefore making transfusion a reasonable option.
Dr. Sampat, Dr. Berger, and Dr. Manian are hospitalists at Massachusetts General Hospital, Boston.
References
1. Carson JL et al. Clinical Practice Guidelines From the AABB: Red Blood Cell Transfusion Thresholds and Storage. JAMA. 2016;316:2025-35.
2. Dwyre DM et al. Hepatitis B, hepatitis C and HIV transfusion-transmitted infections in the 21st century. Vox Sang. 2011;100:92-8.
3. Hébert PC et al. A multicenter, randomized, controlled clinical trial of transfusion requirements in critical care. Transfusion Requirements in Critical Care Investigators, Canadian Critical Care Trials Group. N Engl J Med. 1999;340:409-17.
4. Holst LB et al. Lower versus higher hemoglobin threshold for transfusion in septic shock. N Engl J Med. 2014;371:1381-91.
5. Villanueva C et al. Transfusion strategies for acute upper gastrointestinal bleeding. N Engl J Med. 2013;368:11-21.
6. Jairath V et al. Restrictive versus liberal blood transfusion for acute upper gastrointestinal bleeding (TRIGGER): a pragmatic, open-label, cluster randomised feasibility trial. Lancet. 2015;386:137-44.
7. Hajjar LA et al. Transfusion requirements after cardiac surgery: the TRACS randomized controlled trial. JAMA. 2010;304:1559-67.
8. Carson JL et al. Liberal or restrictive transfusion in high-risk patients after hip surgery. N Engl J Med. 2011;365:2453-62.
9. Sabatine MS et al. Association of hemoglobin levels with clinical outcomes in acute coronary syndromes. Circulation. 2005;111:2042-9.
