Strategies and Outcomes for Proximal and Distal Embolic Protection Devices – A Review

Abstract

Both carotid endarterectomy (CEA) and carotid artery stenting (CAS) are associated with small, but clinically important and discrepant, rates of procedural complications, including cerebral and myocardial ischaemic events, cranial nerve injury and access site haematoma. Embolic protection devices (EPDs) may lower the rate of ipsilateral ischaemic events during CAS and are considered by the majority of interventionists to be mandatory during CAS, although there are no available data from randomised trials based on clinical outcomes to support this practice (perhaps because many thousands of patients would be required to adequately power a trial based on stroke and death endpoints). A recent systematic review of non-randomised data supports the use of EPDs. Worldwide experience demonstrates that all available protection strategies will capture macroemboli generated during endovascular manipulation of carotid bifurcation plaque, thus clearly implying an added level of protection for the brain when these systems are employed, but different philosophies of protection manage the microembolic burden of CAS (i.e. those particles less than 1 mm in diameter) in very different ways. These differences may be assessed by the evaluation of microembolic signals (MES) on transcranial Doppler (TCD) and of new hyperintensities (‘new white lesions’) on diffusion-weighted magnetic resonance imaging (DWMRI) of the brain. Differences between proximal and distal systems may assume clinical relevance, but further work is required before definitive conclusions can be drawn. This article focuses on the clinical and subclinical differences between protection strategies and provides a pragmatic treatment paradigm to support clinical decision-making.