Adam de Havenon, MD

Touzé T, Trinquart L, Felgueiras R, Rerkasem K, Bonati LH, Meliksetyan G, et al. A Clinical Rule (Sex, Contralateral Occlusion, Age, and Restenosis) to Select Patients for Stenting Versus Carotid Endarterectomy: Systematic Review of Observational Studies With Validation in Randomized Trials. Stroke. 2013

The CREST trial and several other large-scale studies have shown that carotid artery stenting (CAS) is associated with a higher periprocedural risk of stroke than carotid endarterectomy (CEA) in patients with symptomatic carotid stenosis. Selected patients would benefit from CAS given increased surgical risk, anatomical abnormality of the neck, or low procedural risk of CAS. Apart from younger age, though, no other variable has been associated with reduced periprocedural risk in CAS. 

In the paper by Emmanuel Touzé et al., a meta-analysis of existing literature was used to find four variables that were significantly associated with equal periprocedural risk for CAS and CEA. They were: sex (female), contralateral occlusion, age (<75), and restenosis (SCAR rule). If any of the criteria were present patients were deemed SCAR negative. The rule was then validated with data from the EVA-3S, SPACE, and ICSS randomized trials with a primary outcome of procedural risk of stroke or death. The rule was then relaxed to identify SCAR negative as having two criteria present and was again validated.

For SCAR negative patients the primary outcome was the same between CAS and CEA, but for SCAR positive patients the risk of CAS was more than twice that of CEA. The statistical methods used to derive and test the rule are incredibly complex and draw on heterogeneous data from a large number of sources. Although the authors suggest that the SCAR rule can “already be considered useful for clinical practice,” I would temper that enthusiasm until other researchers have also validated it.