The Pipeline: Less is More, Slower is Better, and Smaller is Possible

Background and Purpose: Despite experience gained with the Pipeline Embolization Device (PED), the following remain unclear: the significance of intra-procedural aneurysm occlusion after PED placement, if PED’s should be used for treatment of smaller aneurysms, and whether multiple PED’s are needed to achieve occlusion. Methods : Between October 2009 and December 2015, 299 patients, with 342 aneurysms distributed at the internal carotid artery and posterior circulation underwent PED embolization by a single team. Data was collected prospectively and analyzed retrospectively. A new metric assessing flow into the aneurysm following PED placement was created: the Post Stenting Flow Scale (PSFs). It ranges from 0 (no residual flow) to 3 (no significant change in flow). Clinical complications, as well as aneurysm occlusion rates and their predictors, were calculated. Results: The overall peri-procedural clinical complication rate was 18/299 (6%) including 2.7% mortality. All mortality occurred in the giant and fusiform groups. Predictors of clinical complication were aneurysm location (posterior vs. anterior circulation) and the use of multiple PED’s. Clinical complications were more common in fusiform and giant aneurysms 15/168 (9%) than in other aneurysms 3/131 (2.2%). PSFs of 0 was a predictor of vascular complications. Occlusion rate was 77%. PSFs was its only significant predictor. Conclusions: Using a single PED for aneurysm embolization is enough. Rapid and total occlusion of the aneurysm following PED deployment is an ominous sign and warrants clinical attention. Expanding the use of PED’s to treat smaller aneurysms located at the internal carotid artery appears to be a valid strategy.