Written by Mary Marschner
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In a randomized control trial (RCT) for patients with sickle cell anemia presenting with acute chest syndrome (ACS), therapeutic anticoagulation decreased total opiates needed and length of stay.
Do microthrombi play a larger role in acute chest syndrome?
Acute chest syndrome is defined as a new opacity on x-ray associated with fever or new respiratory symptoms in a patient with sickle cell disease. Treatment includes supportive care, pain control, oxygen, antibiotics for presumed infection/inflammation, transfusion (simple vs. exchange transfusion), and prophylactic anticoagulation to prevent VTE.
The etiology of pulmonary vaso-occlusion is caused by the “sickling” of deoxygenated HgS, leading to a cascade of ischemia, infection, thrombosis, and more sickling. Most patients who present to a hospital undergo CTA focusing on large vessel clots, but it has been suggested that microthrombi are contributing to these acute episodes.
The TASC trial investigated if therapeutic anticoagulation could shorten ACS duration in adults with sickle cell disease and no initial pulmonary artery macrothrombosis. This double-blind, multicenter randomized controlled trial enrolled 172 patients over five years into either prophylactic or therapeutic tinzaparin for 7 days. Therapeutic tinzaparin significantly shortened the time to ACS resolution (hazard ratio 0.71; 95%CI 0.51–0.99; p=0.044) and reduced parenteral opioid consumption, without increasing major bleeding.
How does this change my practice?
This study makes so much practical sense that I’m anxious for a larger study that includes not just acute chest but pain crises as well. Due to its small sample size, I am hesitant to change my standard of care yet, but I feel reassured that there was no increased bleeding. While there are a few other small studies looking at therapeutic anticoagulation, no consensus guidelines have been recommended from the American Thoracic Society or American Society of Hematology yet.
Source
Comparison of Prophylactic and Therapeutic Doses of Anticoagulation for Acute Chest Syndrome in Sickle Cell Disease: The TASC Randomized Clinical Trial. Am J Respir Crit Care Med. 2025 Apr 10. doi: 10.1164/rccm.202409-1727OC. Epub ahead of print. PMID: 40209087
