Symptomatic status: as evidenced by TIA or non-severe stroke within the past 12 months attributed to 70% to 99% stenosis of vertebral artery ostium are eligible. Degree of stenosis: >70% and <99%; stenosis may be diagnosed by TCD, MRA, or CTA to qualify for angiogram performed as part of the study protocol, but must be confirmed by catheter angiography for enrollment in the trial. All the patients should be performed with PTAS beyond a duration of 3 weeks from the latest ischemic symptom onset. No fresh infarctions identified on MRI (indicated as high signals on DWI series) upon enrollment.Patient is willing and able to return for all follow-up visits required by the protocol Patient understands the purpose and requirements of the study, can make him/herself understood, and has signed informed consent.