Background The initial experience with the large diameter Penumbra Coil 400 (PC400) system has been positive regarding safety, efficacy, improved packing density and cost effectiveness, but follow-up data are limited.

Methods This is a single-center retrospective review of 76 aneurysms treated with PC400 coils compared with 301 aneurysms treated with a variety of different bare platinum and bioactively coated coils. Atypical and giant aneurysms were excluded as well as those that had undergone previous treatment. Occlusion classification was determined immediately after the procedure and at short-term follow-up.

Results Compared with controls, in the PC400 group fewer coils were used (3.53 vs 5.44, p<0.05), procedure time was decreased (48 vs 64 min, p<0.05) and packing density was increased (31.7% vs 24.8%, p<0.05). There were more grade III aneurysms (71.1% vs 38.2%, p<0.05) and fewer grade I aneurysms (13.2% vs 30.2%, p<0.05) in the PC400 group than in the control group immediately after the procedure. At first follow-up, however, more aneurysms in the PC400 group improved (51.3% vs 28.7%, p<0.05) in angiographic grade leading to similar rates of acceptable outcome (grades I or II) at first follow-up (PC400 79.5% vs control 77.2%). The adverse event rate was similar in the two groups.

Conclusions Large diameter PC400 coils can be used to safely treat cerebral aneurysms with fewer coils, decreased procedure time and increased packing density compared with standard coils. The early angiographic outcome is similar to that achieved with standard coils.