Challenges and Opportunities of Direct Oral Anticoagulant (DOAC) Therapy in Complex Clinical Scenarios: A Comprehensive Review and Practical Guide

Direct oral anticoagulants (DOACs) have emerged as a preferred alternative to vitamin K antagonists (VKAs) for the prevention and treatment of thromboembolic disorders, offering improved safety, predictable pharmacokinetics, and ease of administration. Despite these advantages, their use in complex clinical scenarios presents significant challenges that necessitate individualized therapeutic strategies. This comprehensive review explores the efficacy, safety, and limitations of DOAC therapy in special populations, including patients with renal or hepatic impairment, obesity, cancer-associated thrombosis, and antiphospholipid syndrome. Additionally, we examine their role in uncommon thrombotic conditions such as superficial venous thrombosis, embolic stroke of undetermined source, upper extremity vein thrombosis, inferior vena cava thrombosis, pelvic vein thrombosis, and cerebral vein thrombosis. The pharmacokinetic variability of DOACs in renal and hepatic dysfunction requires caution to balance the bleeding and thrombotic risks. In obesity, altered drug distribution and metabolism raise concerns regarding appropriate dosing and therapeutic efficacy. Cancer-associated thrombosis presents a complex interplay of prothrombotic mechanisms, necessitating careful selection of anticoagulant therapy. Furthermore, the use of DOACs in antiphospholipid syndrome remains controversial due to concerns about recurrent thrombotic events. Finally, in some unusual scenarios like inferior vena cava, pelvic vein, and cerebral vein thrombosis, the use of DOACs has scarce evidence. This review aims to guide clinicians in optimizing anticoagulation management in challenging patient populations by synthesizing current evidence and providing practical recommendations.