Introduction Flow diversion represents a major paradigm shift in the treatment of unruptured intracranial aneurysms. The potential impact of this technique on coil utilization and adjunctive techniques such as balloon-assisted and stent-assisted coiling is unknown. In this study, we assessed the effect of introduction of flow diversion devices on coil and adjunctive techniques utilization. We also performed a matched-pair analysis to assess the efficacy of flow diverters compared to traditional endovascular treatment of unruptured paraclinoid aneurysms.

Methods Retrospective review of consecutive patients with unruptured aneurysms treated at our Institution comparing two groups: (Group 1, patients treated in the 2-year interval preceding introduction of the Pipeline Embolization Device (PED) and Group 2 (patients treated during the 2-year interval following introduction in our practice of the PED. For the matched-pair analysis, 21 eligible patients with 22 paraclinoid aneurysms treated with the PED were matched to historical controls with an aneurysm of similar size and location.

Results Mean aneurysm diameter was 8.7±6.3 mm in Group 1 and 8.5±6.1 mm in Group 2 (p=0.79). There were no significant differences in the location of the aneurysms between the two groups suggesting that changes in referral pattern were not responsible for the observed changes in practice patterns. PED therapy was employed in 38 (21.7%) of 175 aneurysms in Group 2. The proportion of stent-assisted procedures was significantly less in Group 2 as compared to Group 1 (6.9% vs 14.7%, respectively, p=0.04), as was the proportion of patients undergoing parent artery sacrifice (0.6% vs 3.9% respectively, p=0.046). The mean and the median number of coils utilized per aneurysm were 5.4±3.6 and 5 (range 1–18) for Group 1 and 3.2±3.2 and 3 (range 0–19) for Group 2 (p≤0.0001). The pair-matched analysis demonstrated a significant difference in the rate of complete occlusion favoring PED at radiological follow-up (77.3% in the PED vs 45.4% in the control group, p=0.03). Complications rates were similar between the two groups.

Conclusion Flow diversion represents a disruptive technology. More than one fifth of unruptured aneurysms at our institution were treated with PED after introduction of this technology, resulting in marked decreases in coil and stent utilization. Flow diverters achieve a much higher rate of complete angiographic obliteration when compared to other standard endovascular techniques in the treatment of internal carotid artery aneurysms. In this series, this higher angiographic obliteration rate did not occur at the expenses of an increased rate of complications.

Competing interests H Cloft: Cordis Endovascular. G Lanzino: Educational support from ev3 and Synthes. E Crobeddu: None. D Kallmes: ev3, Micrus, MicroVention, Penumbra, Sequent, NFocus.