Here is the design of a clinical trial:

Official Title: The Effect of Riociguat for Peak Cardiac Index on Cardiopulmonary Exercise Test in CTEPH Patients After Normalization of Pulmonary Artery Pressure by Combination Treatment of Riociguat and Balloon Pulmonary Angioplasty

Included conditions:
- Hypertension, Pulmonary

Study Armgroups:
- {'label': 'Active Comparator: Active drug group Riociguat', 'type': 'ACTIVE_COMPARATOR', 'description': 'Riociguat 0.5mg、1.0mg、2.5mg', 'interventionNames': ['Drug: Riociguat Oral Tablet']}
- {'label': 'Placebo group', 'type': 'PLACEBO_COMPARATOR', 'description': 'Placebo 0.5mg、1.0mg、2.5mg', 'interventionNames': ['Drug: Riociguat Oral Tablet']}

Interventions:
- {'type': 'DRUG', 'name': 'Riociguat Oral Tablet', 'description': 'Take any dose of Riociguat from 0.5mg to 2.5mg, or placebo', 'armGroupLabels': ['Active Comparator: Active drug group Riociguat', 'Placebo group']}

Primary Outcomes:
- {'measure': 'Peak CI change', 'description': 'Change in Peak CI during the cardiopulmonary exercise test (CPET)', 'timeFrame': 'from baseline to 16 weeks'}

Please estimate the sample size based on the assumption: 
Power of 80%, two-sided significance level of 5%, and a drop-out rate of 10%.
Sample size calculation
        Preliminary clinical data indicated that discontinuation of riociguat decreased resting CI, estimated by the Fick method, by 0.24âL/min/m2 in 27 inoperable CTEPH patients treated with BPA. The mean change of peak CI during CPET was â0.27âL/min/m2 (SD 0.39) when estimated from the resting CI based on polynomial regression analysis. We assume that the peak CI would remain unchanged in the riociguat continuing group and is the same SD as in the riociguat discontinuing group. With a power of 80% and two-sided significance level of 5%, we calculated that 33âpatients would be necessary for each group, and the total number of participants needed was 66. Assuming a drop-out rate of 10%, the expected number of cases was 36 for each group, for a total of 72 participants.