Comparison of bioactive coils and bare platinum coils for treatment of cerebral aneurysms: the usability and problems of bioactive coils

Objective: Recanalization of cerebral aneurysms after coil embolization remains a serious problem that influences treatment outcomes. Matrix2TM is bioactive, bioabsorbable detachable coil that was developed for the purpose of reducing recanalization. However, the efficacy and safety of the Matrix2TM coil remains controversial. This study compared the safety and efficacy of the Matrix2TM coil with that of bare platinum coils. Methods: We performed 99 endovascular embolizations of cerebral aneurysms between January 2007 and December 2009. The present study included 51 aneurysms for which followup angiography was performed within 1 year after coil embolization. Initial and followup occlusion status, the appearance of highintensity spots (HIS) on magnetic resonance imaging, and the appearance of the white collar sign (suggesting the formation of a neointimal layer) were evaluated. Results: Initial occlusion status did not differ significantly between the bare coil (BC) group and the bioactive coil (BAC) group. However, the rate of further thrombosis was 9.38% in the BC group and 15.8% in the BAC group. In small or medium size aneurysm cases, a tendency toward higher rates of neointimal formation in the aneurysm neck (white collar sign) was seen for the BAC group (BC group: 6.3%, BAC group: 26.3%, p=0.11). However, the rate of appearance of HIS was significantly higher in the BAC group, but was associated with no discernible impact on clinical outcomes. Conclusion: Compared with bare platinum coils, bioactive coils increase the frequency of further thrombosis and provide more durable results following coil embolization of cerebral aneurysms, especially in small or medium size aneurysm cases. However, due consideration must be given to the occurrence of embolic complications.