In-Pipeline Stenosis: Incidence, Predictors, and Clinical Outcomes

BACKGROUND:The Pipeline Embolization Device is a widely utilized flow diverter in the treatment of intracranial aneurysms.OBJECTIVE:To assess the incidence, clinical significance, predictors, and outcomes of in-Pipeline stenosis (IPS).METHODS:Angiographic studies in 139 patients treated between 2011 and 2013 were independently reviewed by 2 authors for the presence of IPS. Multivariable logistic regression analysis was conducted to determine predictors of IPS.RESULTS:A total of 21 (15.8%) patients demonstrated some degree of IPS during the follow-up period at a mean time point of 6.7 months (range, 3-24 months). The stenosis was mild (<50%) in 11 patients, moderate (50%-75%) in 5, and severe (>75%) in 6. None were symptomatic or required further intervention. Sixteen of these 22 patients (73%) had IPS detected within 6 months. IPS was noted in 7.6% (1/13) of patients with posterior circulation aneurysms vs 16.7% (21/126) of those with anterior circulation aneurysms (P = .03). The rate of IPS was 60% (3/5) in patients who did not receive aspirin vs only 14.2% (19/134) in those who received aspirin (P = .02). In multivariable analysis, no aspirin therapy (odds ratio, 10.0; 95% confidence interval, 1.4-67.7; P = .02) and internal carotid artery aneurysm location (odds ratio, 3.1; 95% confidence interval, 1.1-8.8; P = .03) were strong independent predictors of IPS.CONCLUSION:IPS is a common, early, and mostly benign complication. Patients with internal carotid artery aneurysms are more likely to develop IPS. Aspirin plays a key role in preventing IPS. The results of this study further support the safety of flow diverters.ABBREVIATIONS:IPS, in-Pipeline stenosisPED, Pipeline Embolization Device