Table 3 Thresholds for Indications, Technical Success, and Complications

Neurologic complicationComplications Threshold
Asymptomatic Patient (%)Symptomatic Patient (%)
Inappropriate comparison of the thresholds in this table to the reported incidences of complications after CEA might lead to an erroneous conclusion that higher rates of neurologic complications are acceptable for CAS compared with lower rates for CEA: (a) A “threshold” is not intended to represent a desirable incidence of complications. A “threshold” implies a complication rate that is significantly above the expected rate of complications, such that an audit should be conducted to examine the cause of the unexpectedly high incidence of complications. (b) These thresholds are significantly higher than the complication rates for CEA published in the randomized ACAS and NASCET trials. Those trials included only low-risk patients. The thresholds in this document pertain only to high-risk patients. Except for patients treated as part of an approved investigational trial, patients considered to have normal risk of CEA do not fall within the acceptable indications for carotid artery angioplasty and stent placement as defined in this document. (c) The thresholds described in this document are comparable with the incidences of complications resulting from CEA performed on similar high-risk patients. (d) The thresholds described in this document do not apply to low-risk patients treated under an approved investigational trial. Lower thresholds, comparable with the well-established experience with CEA in low-risk patients, would apply for CAS performed under these conditions. (e) The definitions for the neurologic complications on which these thresholds are based differ from those used in many reported series. No accepted, standardized methodology for reporting all neurologic complications exists. The neurologic complications defined in this document should be applicable to a broad range of cerebrovascular interventions and surgery. (f) The thresholds described in this document reflect complications occurring within 30 days of CAS, not immediate postoperative results. (g) Thresholds for the reversible stroke categories are based on the expectation that reversible deficits are likely to be slightly more common than permanent strokes. We recognize that there is not yet adequate scientific literature to confirm this.
* At present, there are minimal and insufficient data available to suggest threshold values for transient deficits after CAS. We believe that these data should be collected and reported to further our understanding of CAS and, perhaps, to help to decrease the incidence of permanent neurologic complications. When adequate data about transient neurologic complications become available, this document will be revised to include threshold values for such transient complications.
† All deaths should be reviewed.
Minor transient deficit**
Major transient deficit**
Minor reversible stroke3.56
Major reversible stroke23
Minor permanent stroke34.5
Major permanent stroke23
    Meets the indications listed in section III.A95%
Technical success90%