American Board of Internal Medicine (ABIM) Certification Practice Exam

Patients taking which type of medications would have an increased risk leading to tPA being contraindicated?

1. Vitamin K antagonists

2. Direct factor Xa inhibitors

3. Thrombopoietin receptor agonists

4. Antiplatelet agents

The correct answer is: Direct factor Xa inhibitors

The most relevant medication class leading to an increased risk that would make tissue plasminogen activator (tPA) contraindicated is direct factor Xa inhibitors. These medications, such as rivaroxaban and apixaban, are anticoagulants that directly inhibit factor Xa in the coagulation cascade. When a patient is taking these medications, there is a heightened risk of bleeding, especially in the context of acute ischemic stroke where tPA is used to dissolve clots. tPA is used to treat certain types of strokes by dissolving blood clots, but its use is limited by the potential for significant hemorrhagic complications. Because direct factor Xa inhibitors cause significant anticoagulation, the risk of intracranial hemorrhage or other bleeding events increases if tPA is administered to patients who are on these drugs. Therefore, the presence of direct factor Xa inhibitors is a strong contraindication for the use of tPA. While vitamin K antagonists, thrombopoietin receptor agonists, and antiplatelet agents carry risks, their impact is generally less direct in terms of immediate bleeding risk related to tPA compared to direct factor Xa inhibitors. Vitamin K antagonists require time to reverse the effects, and their anticoagulation effect isn't as