Effects of Antithrombotic Therapy on Abdominal Aortic Aneurysm Sac Size after Endovascular Repair in Patients with Favorable Neck Anatomy

Purpose: To evaluate the influence of antiplatelet or anticoagulant therapy on sac behavior after endovascular aneurysm repair (EVAR) for abdominal aortic aneurysm (AAA). Materials and Methods: This study retrospectively analyzed data from patients with favorable neck anatomy who underwent EVAR between 2007 and 2019. Patients with ruptured AAA and <= 1 year of sac behavior evaluation were excluded. Sac shrinkage after 1 year, persistent type II endoleak, and late sac expansion were examined. Results: In total, 182 patients with favorable neck anatomy were included in this study. A multivariable analysis identified an occluded inferior mesenteric artery (IMA; P = .049), the presence of a posterior thrombus (P = .009), and no antiplatelet therapy (P = .012) as factors positively associated with sac shrinkage at 1 year. Persistent type II endoleak was detected in 56 (30.8%) patients, with patent IMA (P = .006), the lack of a posterior thrombus (P = .004), the number of patent lumbar arteries (P = .004), and antiplatelet therapy (P = .039) being identified as significant risk factors. The multivariable analysis identified a larger initial AAA diameter (P < .001), the lack of a posterior thrombus (P = .038), and antiplatelet and anticoagulant therapies (P = .038 and P = .003, respectively) as risk factors for late sac expansion. Conclusions: After EVAR in patients with favorable neck anatomy, antiplatelet therapy is associated with the lack of sac regression at 1 year, whereas antiplatelet and anticoagulant therapies are risk factors for late sac expansion.