A 56-year-old man comes to the emergency department due to right lower extremity pain and swelling. The symptoms began shortly after he flew back to the United States from a 7-day cruise in Indonesia. Doppler ultrasonography reveals a femoropopliteal venous thrombosis, and the patient is given anticoagulation with rivaroxaban. Compared to vitamin K antagonists, this patient's treatment is most likely to have which of the following benefits?

Question

A 56-year-old man comes to the emergency department due to right lower extremity pain and swelling.  The symptoms began shortly after he flew back to the United States from a 7-day cruise in Indonesia.  Doppler ultrasonography reveals a femoropopliteal venous thrombosis, and the patient is given anticoagulation with rivaroxaban.  Compared to vitamin K antagonists, this patient's treatment is most likely to have which of the following benefits?

Quizplus · Accepted Answer

11ec160b_3bda_d06d_9249_9b2f52b21db9_MD0001_00 Rivaroxaban is a direct oral anticoagulant (DOAC) that binds to and inhibits factor Xa, thereby preventing conversion of prothrombin to thrombin. DOACs are generally preferred over vitamin K antagonists (VKAs) such as warfarin for most conditions requiring prolonged anticoagulation due to less variability in therapeutic effect. The therapeutic effect of VKAs is affected by changes to dietary intake of vitamin K, disruption to vitamin K- producing intestinal flora (eg, antibiotics), and a wide range of medications that inhibit or induce cytochrome P450 2C9; therefore, patients given VKAs require coagulation monitoring (eg, with INR) to ensure adequate anticoagulation. In contrast, the therapeutic effect of DOACs is not typically altered by environmental or medication changes; therefore, laboratory monitoring is not required. DOACs may also have a lower risk of intracranial bleeding, the most serious risk of anticoagulation, when compared to VKAs. (Choice A) Rates of patient compliance are roughly equivalent for DOACs and VKAs. (Choices B and C) Heparin can cause thrombocytopenia due to either heparin-induced thrombocytopenia type I (nonimmune mediated) or type 2 (immune mediated). VKAs target vitamin K-dependent clotting factors (not platelets), so they do not typically cause thrombocytopenia. VKAs and DOACs have roughly the same efficacy. (Choice D) A loading dose is required with heparin. Some DOACs (eg, rivaroxaban) also require a higher dose for the first few weeks prior to initiating a lower maintenance dose. VKAs do not require a loading dose. Educational objective: Direct oral anticoagulants (DOACs) such as rivaroxaban are often preferred over vitamin K antagonists (VKAs) such as warfarin in the treatment of conditions that require anticoagulation due to less variability in therapeutic drug effect; in contrast to VKAs, the efficacy of DOACs is unaffected by dietary changes and most medications. Therefore, patients given DOACs do not require laboratory monitoring.

A 56-Year-Old Man Comes to the Emergency Department Due to Right