Background and purpose Flow diversion with the Pipeline Embolization Device (PED) has been shown to be effective and safe in several trials and registries. The PUFS trial demonstrated a 5.6% major stroke and neurologic death rate in large and giant internal carotid artery aneurysms. Multiple prior publications suggested a higher complication risk with increasing aneurysm size. We sought to determine the relationship between aneurysm size and primary safety events in the PUFS patient population.

Materials and methods Ten centers prospectively enrolled 107 patients with 109 aneurysms into the safety arm of the PUFS trial. All centers had obtained IRB approval. Prospectively collected information included demographic characteristics, aneurysm size and location, aneurysm neck size, number of PEDs used, and any complications (including stroke and death). All angiographic images were evaluated by an independent Core Radiology Laboratory. All complications were reviewed and adjudicated by a Clinical Events Committee.

Results The rate of major ischemic or hemorrhagic stroke was 4.7% (5/107). Two of these events were fatal. An additional patient experienced a fatal event that was thought to be possibly of neurologic origin, making the neurologic mortality rate 2.8% (3/107). Combined major stroke and neurological mortality rate for the trial was 5.6% (6/107). All primary safety events occurred within the first 6 months post treatment. Of the 109 aneurysms treated, 86 (78.9%) were large (10–24.9 mm), 22 (20.2%) giant (≥25 mm), and 1 (0.9%) small. All of the primary safety events were observed the large aneurysm group, for a major stroke / neurologic death rate of 7.1% (6/84). Complete aneurysm occlusion was noted in 91.8% (79/86) of large and in 90.9% (20/22) of giant aneurysms. However, 4 of the total 6 parent vessel occlusions encountered in the trial occurred in the giant aneurysm group (4/22=18.2%); while only 2 of 86 vessels harboring large aneurysms suffered occlusion (2.3%).

Conclusions All 6 major neurologic morbidity and neurologic mortality events in the PUFS trial was observed in 84 patients harboring large aneurysms, for 7% complication rate in this subgroup. Patients with giant aneurysms suffered no such complications, however, their parent vessel occlusion rates were higher at 18.2% (4/22). More aggressive or more prolonged antiplatelet treatment may be necessary in patients with giant aneurysms treated with flow diversion alone.

Disclosures T. Becske: 2; C; Proctor for Covidien. M. Potts: None. W. Brinjikji: None. D. Kallmes: 1; C; funding for enrollment in clinical trials. 2; C; Covidien: funding for Principal Investigator duties, Steering Committee and Adverse Event Adjudication Committee;. M. Shapiro: 2; C; Covidien proctor. P. Nelson: 2; C; Covidien proctor.