Purpose To determine the rates of neurologic adverse events following Pipeline Embolic Device (PED) placement for intracranial aneurysm treatment.

Methods A retrospective review of medical records was performed at 19 centres to identify consecutive intracranial aneurysms treated with the PED following regulatory approval for marketing the device in the given country. All patients in whom at least one PED was placed and in whom follow-up was available prior to IRB or ethics panel approval were enrolled. Three anatomic/size subgroups were defined, including 1) pre-PComm, internal carotid artery aneurysms 10mm or greater (“large ICA”), 2) ICA aneurysms >10mm and/or at/distal to the PComm region (“other anterior circulation”), and 3) posterior circulation aneurysms. “Primary safety events” included stroke, haemorrhage, parent artery stenosis, permanent cranial neuropathy, and spontaneous rupture of the target aneurysm. Severe safety events were defined as any event causing significant impairment of functioning causing the inability of the subject to carry out usual activities. Statistical analysis was performed using standard summary statistics; p-values comparing subgroups were computed using Pearson's chi-square test for discrete variables and analysis of variance for continuous variables.

Results To date, 580 aneurysms, including 183 large ICA, 344 other anterior circulation, and 53 posterior circulation aneurysms have been treated and followed for a mean duration of 7.8 months (SD 7.3, range 0.1 - 40.8). 437 (76%) of 580 aneurysms were saccular and 80 (14%) were fusiform; 32 (5.5%) were classified as giant (<25mm diameter). 549 (93%) were unruptured. 241 (42%) were treated with multiple PEDs. Primary safety events were noted in 62 (12%) cases. Severe neurological events occurred in 35 (6.8%) cases, and occurred more frequently in posterior circulation aneurysms (7 (13%)) than in either large ICA or other anterior circulation aneurysms (15 (8.8%) and (13 (4.5%), respectively, p=.035). Major stroke occurred in 20 (3.9%) of 515 subjects (4.1%, 3.1%, and 7.5% in large ICA, other anterior circulation, and posterior circulation aneurysms, respectively, p=.31). Ipsilateral intracranial haemorrhage occurred in 12 (2.3%) subjects (3.5%, 1.7%, and 1.9% in large ICA, other anterior circulation, and posterior circulation aneurysms, respectively, p=.47). Spontaneous aneurysm rupture occurred in 3 (0.6%) aneurysms, all of which were giant, resulting in a 9% incidence of rupture in giant aneurysms. Mortality rate was 4.3% and was significantly higher for posterior circulation aneurysms (11.3%) as compared to anterior circulation aneurysms (3.5%, p=.019).

Conclusions Preliminary data indicates that in approximately 7% of aneurysms treated with PED, substantial neurologic complications occurred, with rates of both severe neurologic events and mortality occurring significantly higher in the posterior as compared to the anterior circulation. Both ipsilateral haemorrhage and spontaneous aneurysm rupture were rare, with the latter event limited to giant aneurysms.

Disclosures D. Kallmes: 1; C; MicroVention, Sequent, Benvenue, eV3. 2; C; General Electric, Codman, eV3. E. Boccardi: None. A. Bonafe: None. S. Cekirge: None. D. Fiorella: 2; C; Pipeline proctor, consultant, (<10K, EV3). R. Hanel: None. P. Jabbour: None. E. Levy: None. D. Lopes: 6; C; Receives compensation for training & proctoring for Pipeline devices. P. Lylyk: None. C. McDougall: None. A. Siddiqui: None. I. Szikora: None. H. Woo: None.