Long-Term Durability of Bare-Metal Stenting in Complex Iliac Disease: External Iliac Artery Involvement as the Principal Determinant of Late Patency Loss.

Objective: Long-term durability after endovascular treatment of complex aortoiliac disease remains incompletely defined. The present study evaluated late primary patency after bare-metal stenting (BMS) in TASC C-D lesions and examined whether anatomical extension beyond the common iliac artery influences long-term outcomes independently of traditional TASC classification.

Methods: A single-center retrospective cohort study was conducted including 153 consecutive iliac limbs with TASC C-D occlusive disease treated with BMS between 2014 and 2024. Covered stents, kissing configurations, and acute occlusions were excluded to ensure a homogeneous technical cohort. The primary endpoint was primary patency. Kaplan-Meier estimates were reported through 72 months. Restricted mean survival time (RMST) regression at τ = 72 months and Firth penalized logistic regression were applied to identify independent predictors while minimizing small-event bias.

Results: Technical success exceeded 97%, with no perioperative mortality. Primary patency remained high and comparable between TASC C and D lesions at 72 months (86% vs 84%; log-rank p = 0.8). In contrast, extension into the external iliac artery (EIA) was associated with progressive late attrition. Adjusted RMST analysis demonstrated a 7.6-month reduction in mean primary patency at 72 months for EIA-involved lesions (95% CI -11.6 to -3.6; p < 0.001). Firth regression confirmed increased late risk of patency loss at 60 months (OR 10.5; p = 0.034) and 72 months (OR 25.8; p = 0.003). Technical optimization (best-practice stenting) showed limited and model-dependent mitigation, without consistent protection across time points.

Conclusions: In complex iliac BMS reconstruction, long-term durability appears primarily determined by distal anatomical extension rather than TASC class. External iliac artery involvement identifies a subgroup at risk for late failure and may represent a more clinically meaningful stratification parameter for endovascular planning.