Left Ventricular Assist Device Pump Thrombosis in a Patient Treated with Apixaban

BACKGROUND Direct oral anticoagulants (DOAC) are currently the preferred agents for long-term anticoagulation in the appropriate patient with venous thromboembolism, non-valvular atrial fibrillation, and left ventricular thrombi because of their ease of use, fixed dosing, lack of need for routine monitoring, and limited dietary and drug interactions. However, warfarin is still the agent of choice for preventing thromboembolic events in patients with left ventricular assist devices (LVAD). In this case report, we explore the outcome of using apixaban in a patient with an LVAD. CASE REPORT A 56-year-old woman with morbid obesity and stage D congestive heart failure status after HeartWare ventricular assist device (HVAD) placement 2 years prior, who was on long-term anticoagulation with apixaban after failure of warfarin therapy, presented to the Emergency Department with 2 months of worsening fatigue, dark urine, and 1 day of low-flow alarms from her HVAD. Laboratory and radiographic data were consistent with a diagnosis of pump thrombosis. She underwent pump exchange and was started on a heparin drip. Genetic testing for warfarin resistance was negative. Detailed history-taking revealed that the failure to maintain a therapeutic international normalized ratio (INR) was likely due to dietary factors. She was re-challenged with warfarin, and a therapeutic INR level was reached shortly after initiation. She was later discharged on a stable dose of warfarin and remained in a good clinical state without any major adverse events at the 1-year follow-up. CONCLUSIONS Apixaban can be associated with an increased risk of thrombosis in patients with HVADs and should be used with caution and only in select patients.