Ischemic Stroke During Rivaroxaban Therapy: The Importance of Food-Dependent Absorption and Careful Assessment Before Antithrombotic Escalation.

Ischemic stroke occurring during direct oral anticoagulant (DOAC) therapy for atrial fibrillation represents a frequent and challenging clinical dilemma due to increasing stroke rates and increasing DOAC prescription rates. Such events are often interpreted as treatment failure, prompting escalation with antiplatelet therapy, particularly in the presence of concomitant intracranial atherosclerotic disease (ICAD), and thereby exposing patients to increased bleeding risk. However, apparent DOAC failure may reflect correctable pharmacokinetic or adherence-related factors. We report a 75-year-old man with nonvalvular atrial fibrillation who presented with acute left-sided cerebellar ataxia and inability to sit unsupported. Neuroimaging demonstrated a posterior circulation ischemic stroke associated with intracranial atherosclerotic occlusion of the left vertebral artery, with collateral filling of the left posterior inferior cerebellar artery from the contralateral vertebral artery. Endovascular recanalization was unsuccessful, and the patient received short-term tirofiban due to the identified ICAD, with no hemorrhagic transformation on follow-up imaging. Although the stroke occurred during rivaroxaban therapy, detailed history revealed intake of rivaroxaban 20 mg once daily without food, likely resulting in reduced bioavailability. The event was interpreted as pharmacokinetic underexposure rather than true anticoagulant failure. Antiplatelet escalation was avoided, and anticoagulation was resumed with a food-independent DOAC. The patient remained clinically stable without hemorrhagic complications. This case highlights the importance of careful medication history and pharmacokinetic awareness in patients presenting with ischemic stroke during DOAC therapy. Recognizing apparent rather than true treatment failure can prevent unnecessary antithrombotic escalation and reduce avoidable bleeding risk.