MTM Anticoagulation Management 4 — Questions and Answers
Question 1: A patient on rivaroxaban needs an elective colonoscopy with polyp removal. What is the recommended periprocedural anticoagulation management?
- Continue rivaroxaban through the procedure
- Stop rivaroxaban 24 hours before and restart 24 hours after if hemostasis achieved (Correct answer)
- Bridge with LMWH while rivaroxaban is held
- Stop rivaroxaban 5 days before the procedure
Correct answer: Stop rivaroxaban 24 hours before and restart 24 hours after if hemostasis achieved
For high-bleeding-risk procedures like polypectomy, rivaroxaban should be held for at least 24 hours (or 48 hours for high-bleed-risk) before the procedure with no bridging required.
Question 2: Which laboratory test is most appropriate to monitor anticoagulant effect when using argatroban in a patient with HIT?
- Anti-Xa level
- Activated partial thromboplastin time (aPTT) (Correct answer)
- Thrombin time
- Prothrombin time (PT)
Correct answer: Activated partial thromboplastin time (aPTT)
Argatroban, a direct thrombin inhibitor, is monitored using the aPTT with a target of 1.5–3 times the baseline normal value.
Question 3: A woman with atrial fibrillation on anticoagulation discovers she is pregnant. Which anticoagulant is considered safest during the second trimester?
- Warfarin
- Dabigatran
- Low molecular weight heparin (LMWH) (Correct answer)
- Apixaban
Correct answer: Low molecular weight heparin (LMWH)
LMWH is preferred throughout pregnancy because it does not cross the placenta, unlike warfarin which is teratogenic, and DOACs which lack adequate safety data in pregnancy.
Question 4: A patient's warfarin dose was stable for 6 months but now has an INR of 1.5. They deny dietary changes. What is the MOST important factor to assess?
- Recent sun exposure
- New medications, supplements, or OTC products started (Correct answer)
- Change in sleep patterns
- Increased physical activity level
Correct answer: New medications, supplements, or OTC products started
A drop in INR with stable warfarin dosing most commonly results from drug interactions with inducers of CYP2C9 or reduced warfarin absorption from new medications or supplements.
Question 5: What is the primary mechanism of action of protamine sulfate when used to reverse heparin?
- Competitively inhibits heparin at antithrombin binding sites
- Activates thrombin to overcome heparin inhibition
- Directly binds heparin via electrostatic interaction, forming an inactive complex (Correct answer)
- Inhibits heparin renal excretion to allow natural metabolism
Correct answer: Directly binds heparin via electrostatic interaction, forming an inactive complex
Protamine sulfate, a positively charged protein, binds electrostatically to negatively charged heparin, forming a stable inactive complex that has no anticoagulant activity.
Question 6: An elderly patient taking apixaban for AF falls and sustains a mild head injury. CT head shows no intracranial hemorrhage. How should anticoagulation be managed?
- Permanently discontinue apixaban due to fall risk
- Hold apixaban for 1 week and reassess
- Resume apixaban after 24 hours given no bleeding found and high stroke risk (Correct answer)
- Switch to aspirin for stroke prevention given the fall risk
Correct answer: Resume apixaban after 24 hours given no bleeding found and high stroke risk
In AF patients with high stroke risk and no intracranial hemorrhage, anticoagulation should generally be resumed within 24–48 hours after low-risk head trauma.
Question 7: Which patient would be LEAST appropriate for outpatient DVT management with DOAC therapy?
- A 45-year-old with a first unprovoked DVT and CrCl 55 mL/min
- A 60-year-old with bilateral DVT and mild dyspnea at rest with SpO₂ of 88% (Correct answer)
- A 35-year-old with DVT following a long-haul flight
- A 50-year-old with DVT and a history of one prior VTE event on warfarin
Correct answer: A 60-year-old with bilateral DVT and mild dyspnea at rest with SpO₂ of 88%
Significant hypoxia (SpO₂ 88%) and dyspnea at rest suggest hemodynamic compromise or PE, requiring inpatient evaluation and management rather than outpatient DOAC initiation.
MTM Anticoagulation Management 4
A patient on rivaroxaban needs an elective colonoscopy with polyp removal.
What is the recommended periprocedural anticoagulation management?