Authors: Georgios Maragkos; Peter Kan, MD, MPH; Christoph Griessenauer, MD; Sricharan Gopakumar, BA; Santiago Gomez, MD; Mohamed Salem, MD; Luis Ascanio, MD; Alejandro Enriquez-Marulanda, MD; Abhi Jain; Clemens Schirmer, MD, PhD; Christopher Ogilvy, MD; Ajith Thomas, MD (Brookline, MA)

Introduction: The Pipeline Embolization Device (PED) is a routine choice for the endovascular treatment of select intracranial aneurysms. Its success is based on the high rates of aneurysm occlusion, followed by practically non-existent relapse risk if occlusion occurs. Therefore, identification of patient factors predictive of incomplete occlusion on last angiographic follow-up is critical to its success. Methods: A multi-center retrospective cohort analysis was conducted on consecutive patients treated with PED at 3 academic institutions in the United States. Patients with angiographic follow-up assessing the degree of aneurysm occlusion were selected to identify the factors associated with incomplete occlusion. Results: Among all 3 participating institutions we identified a total of 523 PED placement procedures. Three hundred and ninety-five of these (75.5%) had radiographic follow-up and were included in this analysis (age median 58 years; female-to-male ratio 4.4:1). Complete occlusion (Raymond-Roy class I) was noted in 68.6% of cases, while incomplete occlusion (Raymond-Roy class II or III) at last follow-up was identified in 31.4% after a median of 6 months. After accounting for factor collinearity and confounding, multivariate analysis identified older age (≥70 years; OR=3.07, 95% CI 1.77-5.32, P<0.001), higher maximal diameter (≥15 mm; OR=3.33, CI 1.65-6.71, P=0.001) and fusiform morphology (OR=3.04, CI 1.56-7.42, P=0.002) to be independently associated with higher rates of incomplete occlusion on last follow-up. Conclusion: In this study we provide validation of previous findings that age, aneurysm diameter and fusiform morphology are associated with incomplete aneurysm occlusion after PED placement. Such predictive factors can be utilized to guide individualized treatment selection and counseling in cerebrovascular neurosurgical patients. Furthermore, these results provide a clinical background for research on the biologic factors affecting endothelialization of the PED.