Pipeline Embolization Device in Small Vessels (<2 mm) Shows 52% 1-Year Occlusion, 16.9% Ischemic Events

BackgroundFlow diversion stents (FDS), particularly the Pipeline Embolization Device (PED), have been widely used for intracranial aneurysm (IA) treatment. However, data on PED deployment in small-caliber parent vessels (< 2 mm) remain limited. This study aimed to evaluate the technical feasibility, safety, and efficacy of PED for IAs arising from small-caliber vessels.MethodsThis was a multicenter retrospective study enrolling 71 eligible patients with IA located in parent vessels < 2 mm who underwent PED implantation. The primary safety endpoint included procedure-related death, symptomatic stroke, intracranial hemorrhage and asymptomatic in-stent stenosis; the primary efficacy endpoint was complete aneurysm occlusion [O’Kelly-Marotta (OKM) grade D] on follow-up digital subtraction angiography (DSA). Binary logistic regression analyses were used to identify factors associated with complications and delayed IA occlusion.ResultsThe patient age was 55 (47, 59) years, with 37 (52.1%) males. The follow-up duration was 9 (7, 15) months. Postoperative complications included ischemic events (16.9%), hemorrhagic events (4.2%), and asymptomatic in-stent stenosis (12.7%). The 1-year complete occlusion rate was 52%, whereas the long-term occlusion rate gradually increased to 80% with follow-up beyond 12 months. Univariable analysis showed PED length was associated with both delayed IA occlusion [odds ratio (OR) = 0.91, 95% confidence interval (CI) = 0.83–1.00; p = 0.040] and ischemic complications (OR = 1.36, 95% CI = 1.11–1.66; p = 0.003) and also revealed that pre-existing parent vessel stenosis was strongly associated with asymptomatic in-stent stenosis (OR = 13.50, 95% CI = 2.80–65.04; p = 0.001); multivariable analysis confirmed PED length as an independent predictor of ischemic complications (OR = 1.31, 95% CI = 1.06–1.63; p = 0.013).ConclusionPED deployment in small-caliber parent vessels (