title: Possible failure of novel direct-acting oral anticoagulants in management of pulmonary embolism: a case report.
abstract: BACKGROUND
  The relative effectiveness of vitamin K antagonists compared with novel oral anticoagulants in treating pulmonary embolism remains unclear. Recent trials comparing the efficacy of vitamin K antagonists with factor Xa inhibitors for the treatment of pulmonary emboli have been non-inferiority studies based primarily on risk reduction (such as bleeding events), rather than resolution of specific diseases such as pulmonary embolism. Consequently, there is a lack of evidence indicating which of these agents are more effective. Here, we present a case where pulmonary emboli were treated with novel oral anticoagulants followed by warfarin to discuss the potential limitations in the use of novel oral anticoagulants as prevention or treatment of thromboembolism and the continued role for warfarin in this setting.
  
  
  METHODS
  A 34-year-old African American woman presented to our clinic with shortness of breath and pleuritic chest pain several months post-surgery. She was identified as having multiple bilateral pulmonary embolisms and was treated with several novel oral anticoagulants, which failed to resolve the clots. Complete resolution was achieved upon switching to warfarin.
  
  
  CONCLUSIONS
  The patient described in this report failed to respond to novel oral anticoagulant therapy, but her emboli resolved when she was treated with warfarin. This study challenges the notion that factor Xa inhibitors are better alternatives to vitamin K anticoagulants in the treatment of pulmonary emboli based on their safety profile and ease of use alone. As a result, further post-marketing investigations into the efficacy of these agents in the management of pulmonary emboli may be warranted.
authors.affiliation: Division of Cardiology, Providence-Tarzana Medical Center, Tarzana, CA, 91356, USA. rankinjs@gmail.com.
authors.forename: James
authors.initials: J
authors.lastname: Rankin
authors.affiliation: Division of Cardiology, Providence-Tarzana Medical Center, Tarzana, CA, 91356, USA.
authors.forename: Menachem
authors.initials: M
authors.lastname: Nagar
authors.affiliation: Division of Cardiology, Providence-Tarzana Medical Center, Tarzana, CA, 91356, USA.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Crosby
authors.affiliation: Division of Cardiology, Providence-Tarzana Medical Center, Tarzana, CA, 91356, USA.
authors.forename: Nojan
authors.initials: N
authors.lastname: Toomari
authors.affiliation: Department of Medicine, UCLA David Geffen School of Medicine, Los Angeles, CA, 90095, USA.
authors.forename: Richard
authors.initials: R
authors.lastname: Pietras
authors.affiliation: Division of Cardiology, Providence-Tarzana Medical Center, Tarzana, CA, 91356, USA.|Department of Medicine, UCLA David Geffen School of Medicine, Los Angeles, CA, 90095, USA.
authors.forename: Uri M
authors.initials: UM
authors.lastname: Ben-Zur
mesh_terms: D000284:Administration, Oral; D000328:Adult; D000792:Angiography; D000925:Anticoagulants / Q000008:administration & dosage / Q000627:therapeutic use*; D002637:Chest Pain / Q000000981:diagnostic imaging / Q000209:etiology; D004417:Dyspnea / Q000000981:diagnostic imaging / Q000209:etiology; D005260:Female; D006801:Humans; D011655:Pulmonary Embolism / Q000175:diagnosis / Q000188:drug therapy* / Q000503:physiopathology; D017211:Treatment Failure; D014812:Vitamin K / Q000037:antagonists & inhibitors; D014859:Warfarin / Q000008:administration & dosage / Q000627:therapeutic use*
chemical_list: D000925:Anticoagulants; D014812:Vitamin K; D014859:Warfarin
keywords: Anticoagulant therapy; Case report; Embolism; Factor Xa inhibitor; Thrombosis; Warfarin