What was the residual stenosis percentage reported in the OASIS IDE trial?

• A. 6%
• B. 17%
• C. 12%
• D. 20%

Answer: (B)

Residual stenosis is the amount of narrowing that remains in the vessel after the procedure. It reflects how completely the vessel has been opened and how well the intervention succeeded technically. In the OASIS IDE trial, the average residual stenosis after treatment was 17%, meaning the procedure relieved most of the narrowing but left about 17% still narrowed. This level sits within an acceptable range for endovascular carotid interventions, showing good technical performance without requiring reintervention for overly high residual narrowing. The other numbers would imply either unusually tight residual narrowing (6%), a smaller but still plausible result (12%), or a more substantial residual narrowing (20%), none of which match the trial’s reported figure.