Endovascular coiling of cerebral aneurysms using "bioactive" or coated-coil technologies: a systematic review of the literature.

SUMMARY: Second-generation coils have been available since 2002. We wanted to assess their performance and appraise available evidence. Therefore we performed a systematic review of the literature from 2002 to 2007. There were 27 studies with a total of 2390 patients that met pre-specified inclusion criteria. All studies were classed as having a high risk of bias. There were no randomized trials and for most studies results were not independently assessed and follow-up periods were short (mean 7 months). There were large differences in demographic and aneurysm characteristics, making comparisons between coil cohorts difficult. Procedure-related morbidity and mortality were similar for all coil types. Hemorrhagic events during follow-up were few, in the range of 1%/year for all coil types. The available literature is of poor quality and clinical series provide very little evidence in favor of second-generation coils. Positive randomized trial results are needed to justify routine clinical use. This systematic review illustrates the failure of the industry, the regulatory authorities, and the neurointerventional community combined to provide a reliable and prudent approach to the introduction of new devices.