Treatment of unruptured intracranial aneurysms with the pipeline embolization device

The pipeline embolization device (PED; ev3 Endovascular, Plymouth, MN, USA) is a flow-diverter used in the endovascular treatment of intracranial aneurysms, particularly those with unfavorable configurations. It causes progressive flow redirection leading to aneurysm thrombosis. This study aimed to present a systematic review of the published literature on the clinical outcomes of PED. A Medline search of the English language literature was performed using the keywords "intracranial aneurysms" and "pipeline embolization device" or "flow diverters". The inclusion criteria were: n > 10 patients; unruptured aneurysms; documentation of complications; and at least 3 months of follow-up. A total of 13 studies, with 905 patients and 1043 aneurysms, were included. The mean age was 53.8 years, with women comprising 76.3% of patients. The mean aneurysm diameter was 11.1 mm with 37% classed as large aneurysms and 10% classed as giant. The cumulative mortality rate was 2.3%. Seventeen patients had a stroke (1.9%), while 19 (2.0%) had a transient ischemic attack and 21 patients (2.3%) had an intracranial hemorrhage. The two outcome measures were the cumulative event rate (16.7%) and the 6 month aneurysm occlusion rate (79.7%). A funnel plot with study size plotted against the two outcome measures revealed publication bias. Data from recent studies suggest that complication and mortality rates associated with PED may be similar to other contemporary endovascular techniques, with a better 6 month aneurysm occlusion rate. More prospective clinical trials are warranted to further validate these results.