Here is the design of a clinical trial:

Official Title: A Multicenter, Prospective, Randomized, Open-label, Blinded End-point Clinical Study to Evaluate the Safety and Efficacy of Intracranial Balloon Angioplasty Plus Aggressive Medical Management for Symptomatic Intracranial Artery Stenosis

Included conditions:
- Intracranial Artery Stenosis

Study Armgroups:
- {'label': 'Intracranial balloon angioplasty and aggressive medical management', 'type': 'EXPERIMENTAL', 'description': 'All the participants in this group will be given Intracranial balloon angioplasty and aggressive medical management.', 'interventionNames': ['Device: intracranial balloon angioplasty', 'Drug: aggressive medical management']}
- {'label': 'Aggressive Medical management', 'type': 'EXPERIMENTAL', 'description': 'All the participants in this group will be given aggressive medical management alone.', 'interventionNames': ['Drug: aggressive medical management']}

Interventions:
- {'type': 'DEVICE', 'name': 'intracranial balloon angioplasty', 'description': 'A balloon (recommending the Neuro RX and Neuro LPS Intracranial Balloon Dilation Catheter \\[Sinomed Inc., Tianjin, China\\]) is navigated by the microwire to the lesion of the target artery.', 'armGroupLabels': ['Intracranial balloon angioplasty and aggressive medical management']}
- {'type': 'DRUG', 'name': 'aggressive medical management', 'description': 'Aspirin 100mg once/day during the follow-up period, Clopidogrel 75mg once/day for at least 90 days, Atorvastatin 20-80mg once/day as the situation requires and risk factors management including blood pressure to maintain 130-140/80-90 mmHg and LDL lower than 70 mg/dl or 1.8mmol/L.', 'armGroupLabels': ['Aggressive Medical management', 'Intracranial balloon angioplasty and aggressive medical management']}

Primary Outcomes:
- {'measure': 'Stroke or death within 30 days after enrollment or after balloon angioplasty procedure of the qualifying lesion during follow-up, or any ischemic stroke or revascularization from the qualifying artery beyond 30 days through 12 months after enrollment', 'description': 'This outcome includes ischemic/hemorrhagic stroke and all-cause death within 30 days after enrollment or after balloon angioplasty procedure of the qualifying lesion during follow-up, or any ischemic stroke and revascularization from the original culprit symptomatic intracranial artery beyond 30 days through 12 months after enrollment.', 'timeFrame': '12 months'}

Please estimate the sample size based on the assumption: 
80% statistical power, one-sided α of 2.5%, and a 10% dropout rate.
Sample size
        According to VISSIT trial and a previous randomised trial in China, the composite event rate of the primary outcome in the control group is anticipated to be 15%.4 14 As to the balloon angioplasty group, we assume a 7% of the primary outcome based on studies of angioplasty without stenting9 15 and investigatorsâ clinical practice experience in China. As a result, the sample size needs to detect an 8% absolute difference. A total of 512 patients (256 per group) will be enrolled considering an 80% statistical power at a one-sided Î± of 2.5% and a 10% dropout rate.