Objective Flow diversion using the Pipeline embolization device (PED) has become a widely used treatment method for intracranial aneurysms. However, a subset of aneurysms will fail to occlude following treatment and the factors that influence the efficacy of flow diversion remain uncertain. As smaller diameter PEDs inherently have greater metal density than larger devices, we elected to investigate whether PED diameter influences treatment efficacy when using a single device. We also evaluated other factors that may influence treatment outcomes with PED.

Methods We retrospectively evaluated all patients treated for an intracranial saccular aneurysm at our institution with a single PED at least 12 months prior to the time of data collection. Patients treated with multiple devices, adjunctive coiling, traumatic and fusiform target aneurysms, as well as patients with inadequate imaging follow-up (<12 months) were excluded.

Results 158 aneurysms in 124 patients (128 treatments) met the inclusion criteria for our study. 123 aneurysms (80%) were occluded over an average follow-up of 26.6 months. Multivariable logistic regression showed that branch vessel incorporation into the target aneurysm sac (p<0.001, OR=0.15) was significantly associated with aneurysm persistence, while smaller PED diameter was significantly associated with aneurysm occlusion (p=0.008; OR=0.30).

Conclusions PED diameter significantly impacts outcomes when using a single device for the treatment of small anterior circulation intracranial saccular aneurysms, most likely due to the inherent greater metal density of smaller devices. This factor should be taken into account when planning endovascular aneurysm treatment with PED.