Apixaban Failure in A Post-Bariatric Surgery Female Patient with Thoracic Aortic Thrombus Secondary to Covid-19.

A floating thrombus in the thoracic aorta represents a rare vascular condition frequently associated with morbidity and mortality. There is no standardised management approach, but options potentially include anticoagulation therapy, surgical intervention or a combination of these. Clinicians are increasingly selecting direct oral anticoagulants (DOACs) due to predictable pharmacokinetics. Here, we present a 37-year-old female with a history of Roux-en-Y gastric bypass surgery for obesity, who was found to have an incidental floating thrombus in the thoracic aorta during evaluation for generalised weakness and altered mentation following a recent COVID-19 infection. The patient was initially treated with intravenous heparin and subsequently transitioned to apixaban. Despite medication adherence, she presented two weeks later with worsening mental status and bilateral leg swelling. Repeat imaging revealed rupture of the thrombus, leading to right renal and bowel infarctions. The failure of anticoagulation was attributed to malabsorption secondary to her bariatric surgery. Despite aggressive interventions, the patient ultimately developed multisystem organ failure and succumbed to her illness. Literature suggests that DOACs may be less effective in post-bariatric patients due to altered pharmacokinetics. Due to the absence of clinical guidelines for post-bariatric patients, we recommend full-dose anticoagulation with warfarin, a vitamin K antagonist, to enable therapeutic international normalised ratio (INR) monitoring and necessary dose adjustments. DOACs are less effective in this population, particularly in hypercoagulable states, and the lack of monitoring increases the risk of treatment failure and subsequent life-threatening complications. This case report is of apixaban treatment failure in a female patient with a Roux-en-Y gastric bypass. LEARNING POINTS: There is no established management of floating aortic mural thrombus detected by computed tomography.The efficacy of oral anticoagulants after bariatric surgery is uncertain.