Venous Thromboembolism, Anticoagulation, and Risk of Bleeding

Jul 15, 2016   |  Redah Mahmood, MD
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Introduction

In the United States, the currently available direct oral anticoagulants (DOACs) include dabigatran, rivaroxaban, apixaban, and edoxaban.1 As of 2015, all four agents have been approved by the US Food and Drug Administration (FDA) for the treatment of venous thromboembolism (VTE) and have shown non-inferiority to a vitamin K antagonist in the prevention and treatment of VTE.2-5 Dabigatran is currently the only DOAC that has an FDA-approved reversal agent, idarucizumab, now available for in-hospital administration in the United States.6 Idarucizumab is a monoclonal antibody fragment that binds specifically to dabigatran with an affinity more than 350 times that of thrombin, resulting in neutralization of dabigatran's anticoagulant ability. Clinical trials are currently under way to develop "antidotes" or specific reversal agents for Xa inhibitors such as rivaroxaban and apixaban. While there is no FDA approved reversal agent yet for the other three DOACs, in 2011, Eerenbur and colleagues studied 12 patients and demonstrated that prothrombin complex "immediately and completely reverses the anticoagulant effect of rivaroxaban in healthy subjects;" however, this effect was not seen on the anticoagulant action of dabigatran.7

Case Presentation

A 69-year-old female with a past medical history of controlled hypertension, diabetes, dyslipidemia, hypothyroidism, and gastroesophageal reflux disease is admitted for abdominal pain. She is found to have acute cholecystitis and undergoes a laparoscopic cholecystectomy. Postoperatively, the patient has an uneventful course and is on appropriate deep venous thrombosis (DVT) prophylaxis. One week after discharge, the patient presents to your office and complains that her right leg is swollen, warm, and painful. A venous duplex ultrasound is performed in the office. The images are shown below.

Figure 1

Figure 1

Figure 2

Figure 2

The ultrasound demonstrates an acute right common femoral vein DVT at the mid-vessel, demonstrated by dilatation of the femoral vein seen below the femoral artery in the transverse image (Figure 1) and with non-compressibility of the femoral vein shown to the right. In Figure 2, the femoral vein (bottom vessel, inferior to the femoral artery) demonstrates dilatation with no color flow through the vein (color Doppler image on the right), consistent with an occlusive femoral vein thrombus.

When questioned, the patient denies ever having a gastrointestinal (GI ) bleed, but a doctor told her "a long time ago" that she had an ulcer in her stomach; no esophagogastroduodenoscopy was ever performed. Pertinent laboratories include hemoglobin of 13.2 g/dL, MCV of 90.2, platelet count of 193, creatinine of 1.2, and creatinine clearance of 82 mL/min. Aspartate aminotransferase and alanine aminotransferase are within normal limits.

Which of the following is the best DOAC for this patient?

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