Case Presentation:
Hypercoagulable disorders pose an increased lifetime risk of developing venous thromboembolic events (VTE). It is established that patients with these disorders usually need lifelong anticoagulation once they have more than one thromboembolic event. With the emergence of novel oral anticoagulants (NOAC), management of these patients has been streamlined. However, in times of medical illness or surgery, NOACs may not be optimal. These patients may require more aggressive individualized therapy to prevent VTE.
This case involves a 48-year-old gentleman with a past medical history of a prothrombin gene mutation complicated by two episodes of provoked VTE four and ten months prior. He had been taking Apixaban, a NOAC, indefinitely as a result. He elected to undergo total hip replacement for osteoarthritis. At the time of the operation, the patient had stopped taking Apixaban for 48 hours under the advisement of his hematologist. The patient tolerated the surgery well without any bleeding complications. Apixaban 5 milligrams (mg) was restarted within six hours after surgery and continued twice daily. The next day, the patient underwent physical therapy and tolerated early ambulation. However, he started to have right lower extremity pain and swelling. An ultrasound of the right lower extremity was significant for an acute proximal deep vein thrombus. Apixaban was then increased to 10mg twice daily. The patient’s symptoms and leg swelling improved over the next two days and he was discharged on the higher dose of Apixaban.
Discussion:
NOACs are a mainstream method of anticoagulation for various types of pro-thrombotic illnesses and predispositions. This is due to their ability to be therapeutic at onset, the convenience of not requiring periodic monitoring of drug levels, shorter half-lives, and ease of compliance. However, hypercoagulable patients may not respond to the standard doses of NOACs during times of stress. Unfortunately, there are not many studies testing the effectiveness of NOACs at different dosage levels in preventing VTE among high risk populations. Furthermore, the standard coagulation assays have not been reliable measurements of NOAC activity.
Studies have primarily focused on heparin products and vitamin K antagonists for VTE prevention. Across multiple studies, low-molecular-weight heparin (LMWH) seems to provide better outcomes for high risk surgical and medically ill patients. This is especially true, when therapy is guided by monitoring Factor Xa levels. The patient in this case is a high risk for VTE complications due to his prothrombin gene mutation and the type of surgery he underwent. Despite every precaution to limit the interval off Apixaban and encourage early ambulation, he still developed a DVT in-hospital.
Conclusions:
Going forward, it may be best to transition high risk patients to LMWH therapy peri-operatively and early post-op until NOACs are proven to be an effective alternative.