PDF icon Download PDF
Semin Thromb Hemost 2024; 50(04): 527-536
DOI: 10.1055/s-0043-1774795
Review Article

What Role Does Microthrombosis Play in Long COVID?

Toshiaki Iba 
1   Department of Emergency and Disaster Medicine, Juntendo University Graduate School of Medicine, Tokyo, Japan
,
Jean M. Connors 
2   Division of Hematology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts
,
Jerrold H. Levy 
3   Department of Anesthesiology, Critical Care, and Surgery, Duke University School of Medicine, Durham, North Carolina
› Author Affiliations
Funding This work was supported in part by a Grant-in-Aid for Special Research in Subsidies for ordinary expenses of private schools from The Promotion and Mutual Aid Corporation for Private Schools of Japan.
› Further Information
   Permissions and Reprints
Preview

Abstract

Soon after the outbreak of coronavirus disease 2019 (COVID-19), unexplained sustained fatigue, cognitive disturbance, and muscle ache/weakness were reported in patients who had recovered from acute COVID-19 infection. This abnormal condition has been recognized as “long COVID (postacute sequelae of COVID-19 [PASC])” with a prevalence estimated to be from 10 to 20% of convalescent patients. Although the pathophysiology of PASC has been studied, the exact mechanism remains obscure. Microclots in circulation can represent one of the possible causes of PASC. Although hypercoagulability and thrombosis are critical mechanisms of acute COVID-19, recent studies have reported that thromboinflammation continues in some patients, even after the virus has cleared. Viral spike proteins and RNA can be detected months after patients have recovered, findings that may be responsible for persistent thromboinflammation and the development of microclots. Despite this theory, long-term results of anticoagulation, antiplatelet therapy, and vascular endothelial protection are inconsistent, and could not always show beneficial treatment effects. In summary, PASC reflects a heterogeneous condition, and microclots cannot explain all the presenting symptoms. After clarification of the pathomechanisms of each symptom, a symptom- or biomarker-based stratified approach should be considered for future studies.

Keywords

long COVID-19 - microclots - SARS-CoV-2 spike protein - coagulation - platelets

Authors' Contributions

All authors met authorship criteria and participated significantly in the study. T.I. wrote the draft. J.M.C. and J.H.L. reviewed and revised the manuscript. All authors read and approved the final manuscript.




Publication History

Article published online:
25 September 2023

© 2023. Thieme. All rights reserved.

Thieme Medical Publishers, Inc.
333 Seventh Avenue, 18th Floor, New York, NY 10001, USA