Here is the design of a clinical trial:

Official Title: The Effect of Perioperative LevosIMendan Administration on Postoperative N-terminal pRo Brain Natriuretic Peptide Concentration in Patients With Increased cardiOVascular Risk Factors Undergoing Noncardiac surgEry - A Double-blinded Randomized Clinical Trial

Included conditions:
- Cardiovascular Risk Factor

Study Armgroups:
- {'label': 'Levosimendan', 'type': 'ACTIVE_COMPARATOR', 'description': 'Patients receive a continuous infusion of 12.5mg solved in 50mL Levosimendan for up to 24 hours. Infusion will be started with surgical skin incision.', 'interventionNames': ['Drug: Levosimendan']}
- {'label': 'Placebo', 'type': 'PLACEBO_COMPARATOR', 'description': 'Patients receive a continuous infusion containing a placebo solved in 50mL for up to 24 hours. Infusion will be started with surgical skin incision.', 'interventionNames': ['Drug: Placebo']}

Interventions:
- {'type': 'DRUG', 'name': 'Levosimendan', 'description': 'Levosimendan 2.5 mg/ml injection contains levosimendan 2.5 mg, povidone 10.0 mg, citric acid, anhydrous 2.0 mg and ethanol, anhydrous to 1.0 mL. Levosimendan injection is a clear, yellow to orange solution. Immediately after skin incision patients allocated to the verum group will receive a dose of 12.5 mg in 500 mL of levosimendan.', 'armGroupLabels': ['Levosimendan']}
- {'type': 'DRUG', 'name': 'Placebo', 'description': 'Placebo 2.5 mg/ml injection contains riboflavine sodium phosphate 0.4 mg, dehydrated alcohol 100 mg and water for injection to 1 mL.\n\nImmediately after skin incision patients allocated to the placebo group will receive 500 mL of 5% Glucose.', 'armGroupLabels': ['Placebo']}

Primary Outcomes:
- {'measure': 'Postoperative maximum NT-proBNP concentration', 'description': 'The administration of levosimendan improves LVEF and myocardial oxygen perfusion, which will be reflected in a decrease of postoperative NT-proBNP concentration.Since NT-proBNP is a strong predictor for postoperative cardiovascular complications in patients undergoing noncardiac surgery, we want to test the efficiency of levosimendan to decrease postoperative maxNT-proBNP concentrations in patients with increased cardiac risk factors undergoing moderate- to high-risk noncardiac surgery.', 'timeFrame': 'First 5 Postoperative Days'}

Please estimate the sample size based on the assumption: 
Significance level adjusted using O'Brien-Flemming's design for interim analysis, 80% power, 5% dropout rate, 10,000 bootstrap samples for Wilcoxon test statistics.
Sample size considerations
        For the control group, data from a previous study were available, where NT-pro-BNP was measured within 1 hour after surgery and on postoperative day 1 and 3.7 The maximum of these values was calculated. For the calculation of the sample size, we assume median maximum NT-pro-BNP is reduced by 37%20 in the treatment group. To estimate the power, the distribution of the z-approximations of the Wilcoxon test statistics was estimated using the bootstrap method. A total of 10 000 bootstrap samples were drawn. The data for the control group were sampled from the data from the previous study.7 The data for the treatment group was sampled from the same data set, where all values were reduced by 37%. We considered a drop-out rate of 5%. With a total sample size of 230 (115 per group, with a planned interim analysis after 38 patients per group) the overall estimated power (ie, the power to reject either at interim or at the final analysis) is 80%. To correct for multiple testing due to the interim analysis, O'Brien-Flemmingâs design will be used (see statistical analysis).