Evidence overview: benefit of cerebral protection devices during carotid artery stenting

Embolic protection devices (EPDs) are often used during carotid angioplasty and stenting (CAS) to reduce procedural cerebral emboli. This manuscript seeks to present an overview of evidence on EPDs during CAS. There are three categories of EPDs: distal occlusion (DO-EPD), filter (F-EPD) and proximal occlusion (PO-EPD). DO and F-EPDs have the disadvantage that the device has to be advanced through the stenosis, without protection and that the device may damage the distal internal carotid artery (ICA). F-EPDs have the advantage of maintaining antegrade flow throughout the procedure. PO-EPDs occlude the ICA and external carotid artery (ECA) (blocking antegrade flow), but do not require manipulation of the stenosis before protection is established. All devices add to procedural time and costs. Many single-center series and meta-analyses have shown lower incidence of procedural complications and surrogate endpoints when EPDs are used. However, these series are hampered by a serious confounder: protected cases were generally performed later, when institutions had more experience and when newer stents, techniques etc. had become available. Two small randomized trials showed no difference between filter-protected and unprotected procedures in clinical outcome, but found significantly more surrogate endpoints (diffusion-weighted MRI lesions and transcranial Doppler detected micro-emboli) in the protected groups. Comparing between groups of EPDs, some studies slightly favored PO to F-EPDs, while others found no difference. All devices were associated with low numbers of clinical cerebral complications, but frequent surrogate signs of cerebral embolization. In conclusion, all currently available EPDs still result in some degree of cerebral embolization. No solid recommendation for a particular type of EPDs, if any, can be derived from literature.