{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,8]],"date-time":"2026-01-08T07:03:48Z","timestamp":1767855828930,"version":"3.49.0"},"reference-count":14,"publisher":"Oxford University Press (OUP)","issue":"6","license":[{"start":{"date-parts":[[2021,6,5]],"date-time":"2021-06-05T00:00:00Z","timestamp":1622851200000},"content-version":"vor","delay-in-days":7,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2021,5,29]]},"abstract":"<jats:title>Abstract<\/jats:title>\n               <jats:sec>\n                  <jats:title>Background<\/jats:title>\n                  <jats:p>Severe acute respiratory syndrome coronavirus 2 disease is strongly associated with a high incidence of thrombotic events. Anticoagulation could be a cornerstone in successfully managing severe forms of coronavirus disease 2019 (COVID-19). However, optimal anticoagulant dosing in elderly patients is challenging because of high risk of both thrombosis and bleeding.<\/jats:p>\n               <\/jats:sec>\n               <jats:sec>\n                  <jats:title>Case summary<\/jats:title>\n                  <jats:p>We present here the case of an 89-year-old patient receiving warfarin for atrial fibrillation and valvular heart disease, admitted to the intensive care unit for respiratory failure due to COVID-19. The patient presented with a severe epistaxis associated with warfarin overdose [international normalized ratio (INR)\u2009&amp;gt;\u200910]. After a successful initial reversal using vitamin K per os, INR values greatly fluctuated up to 10, requiring repeated administrations of vitamin K. Despite starting low-molecular-weight heparin therapy at therapeutic dose as soon as INR value was below 2.0, the patient further developed an acute bilateral and proximal pulmonary embolism concomitantly with a sharp D-dimer increase. The combination of azithromycin intake, a known inhibitor of CYP2C9, with the presence of CYP2C9*2 and \u22121639G&amp;gt;A VKORC1, two variants associated with warfarin hypersensitivity, have likely contributed to explain the warfarin overdose and the difficulty to reverse warfarin effect in this patient.<\/jats:p>\n               <\/jats:sec>\n               <jats:sec>\n                  <jats:title>Discussion<\/jats:title>\n                  <jats:p>This case report illustrates the complexity of COVID-19 pathophysiology and its management for physicians, especially in patients receiving vitamin K antagonists (VKAs). Infection, concurrent medication use, and pharmacogenetic factors involved in VKA metabolism and pharmacodynamics may lead to a loss of control of anticoagulation. Pulmonary embolism should still be considered in COVID-19 patients even with effective or overdosed anticoagulant therapy.<\/jats:p>\n               <\/jats:sec>","DOI":"10.1093\/ehjcr\/ytab206","type":"journal-article","created":{"date-parts":[[2021,6,5]],"date-time":"2021-06-05T11:28:30Z","timestamp":1622892510000},"source":"Crossref","is-referenced-by-count":2,"title":["Unexpected acute pulmonary embolism in an old COVID-19 patient with warfarin overdose: a case report"],"prefix":"10.1093","volume":"5","author":[{"given":"Maxime","family":"Coutrot","sequence":"first","affiliation":[{"name":"Department of Anaesthesiology, Critical Care Medicine and Burn Unit, AP-HP, Saint Louis and Lariboisi\u00e8re University Hospitals, 1 Avenue Claude Vellefaux, 75010 Paris, France"},{"name":"INSERM UMR-S 942, 41 boulevard de la Chapelle, 75475 Paris Cedex 10, Lariboisi\u00e8re Hospital, Paris, France"},{"name":"FHU PROMICE, 2 Rue Ambroise Par\u00e9, 75010 Paris\u200c, France"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Maxime","family":"Delrue","sequence":"additional","affiliation":[{"name":"Service d\u2019h\u00e9matologie biologique, H\u00f4pital Lariboisi\u00e8re, 2rue Ambroise Pare \u0301,75010 Paris, Universit\u00e9 de Paris, Paris, France"},{"name":"EA 3518, Institut de Recherche Saint-Louis, 1 Avenue Claude Vellefaux, 75010 Paris, Universit\u00e9 de Paris, Paris, France"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"B\u00e9rang\u00e8re S","family":"Joly","sequence":"additional","affiliation":[{"name":"Service d\u2019h\u00e9matologie biologique, H\u00f4pital Lariboisi\u00e8re, 2rue Ambroise Pare \u0301,75010 Paris, Universit\u00e9 de Paris, Paris, France"},{"name":"EA 3518, Institut de Recherche Saint-Louis, 1 Avenue Claude Vellefaux, 75010 Paris, Universit\u00e9 de Paris, Paris, 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