Here is the design of a clinical trial:

Official Title: Evaluation of the Efficacy of Different Duration of a Proton Pump Inhibitor in the Prevention of Upper Gastrointestinal Mucosal Injury in Patients Taking 12-month Dual Antiplatelet Therapy After Coronary Artery Bypass Grafting

Included conditions:
- Gastrointestinal Ulcer (Peptic) or Erosion
- Anti-Platelet Therapy
- Coronary Artery Bypass

Study Armgroups:
- {'label': 'One month of therapy', 'type': 'ACTIVE_COMPARATOR', 'description': 'Pantoprazole, 40mg, tablet, oral, once daily for 1 month', 'interventionNames': ['Drug: Pantoprazole']}
- {'label': 'Twelve months of therapy', 'type': 'EXPERIMENTAL', 'description': 'Pantoprazole, 40mg, tablet, oral, once daily for 12 months', 'interventionNames': ['Drug: Pantoprazole']}

Interventions:
- {'type': 'DRUG', 'name': 'Pantoprazole', 'description': 'Pantoprazole (40mg qd) will be concomitant used with DAPT', 'armGroupLabels': ['One month of therapy', 'Twelve months of therapy'], 'otherNames': ['PANTOLOC, Tablet from Takeda Pharmaceutical Company Limited']}

Primary Outcomes:
- {'measure': 'Percentage of patients with gastroduodenal erosions and ulcers evaluated by EGD.', 'description': 'Gastroduodenal erosions and ulcers will be assessed according to the Lanza Endoscopic Scoring System. Lanza score is a categorical score (0-4) and defined as follows: 0, normal; 1, mucosal hemorrhages only; 2, 1-2 erosions; 3, 3-10 erosions; 4, \\>10 erosions or an ulcer ≥3 mm. In addition, ≥1 ulcer with a diameter no less than 5mm will be grouped separately.', 'timeFrame': 'within 12 months after randomization'}

Please estimate the sample size based on the assumption: 
A two-sided α of 0.05, a randomization ratio of 1:1, and a power of 80% are assumed. A 20% drop-out rate is also considered.
Sample size
        According to the results of the preliminary study, the cumulative incidence of severe gastric and duodenal bulb erosion and ulcers of the 1-month PPI treatment group is assumed to be 36%, and that of the 12-month PPI treatment group was assumed to be 18%. Based on a two-sided Î± of 0.05 and a randomization ratio of 1:1, a total of 186 subjects are required to provide a power of 80%. Considering a 20% drop-out rate, the sample size of 232 subjects was determined.