Here is the design of a clinical trial:

Official Title: N/A

Included conditions:
- Complex Valvular Heart Surgery

Study Armgroups:
- {'label': 'IV iron', 'type': 'EXPERIMENTAL', 'description': 'The patients will receive iron isomaltoside 1000 (Monofer®) as an i.v. infusion of 1000 mg (diluted with normal saline, 10 mg/ml) twice; 3 days before surgery and 3 days after surgery. They will receive iron isomaltoside 1000 (Monofer®) 1000 mg over 15 min.', 'interventionNames': ['Drug: iron isomaltoside 1000 (Monofer®)']}
- {'label': 'Control', 'type': 'PLACEBO_COMPARATOR', 'description': 'The patients will receive normal saline 100 ml as an i.v. infusion twice; 3 days before surgery and 3 days after surgery. They will receive normal saline 100 ml over 15 min.', 'interventionNames': ['Drug: normal saline 100 ml']}

Interventions:
- {'type': 'DRUG', 'name': 'iron isomaltoside 1000 (Monofer®)', 'description': 'The patients will receive iron isomaltoside 1000 (Monofer®) as an i.v. infusion of 1000 mg (diluted with normal saline, 10 mg/ml) twice; 3 days before surgery and 3 days after surgery. They will receive iron isomaltoside 1000 (Monofer®) 1000 mg over 15 min.', 'armGroupLabels': ['IV iron']}
- {'type': 'DRUG', 'name': 'normal saline 100 ml', 'description': 'The patients will receive normal saline 100 ml as an i.v. infusion twice; 3 days before surgery and 3 days after surgery. They will receive normal saline 100 ml over 15 min.', 'armGroupLabels': ['Control']}

Primary Outcomes:
- {'measure': 'the proportion of patients who need blood transfusion', 'description': 'Investigator will assess the number of patients in each group who will need blood transfusion during hospital stays, and evaluate the effect of iron isomaltoside 1000 (Monofer®) on perioperative blood transfusion.', 'timeFrame': 'patients will be followed for the duration of hospital stay, an expected average of 10 days after surgery'}

Please estimate the sample size based on the assumption: 
Significance level at 0.05, power at 80%, effect size of 0.5, two-sided test, 10% dropout rate
Sample size
        Sample size estimation is based on the null and alternative hypotheses. In our study, the null hypothesis is that âIVFe has no significantly different effect on Hb level and transfusion need after complex cardiac surgeryâ and we want to prove that the null hypothesis is wrong for replacing the alternative hypothesis by the two-sided test method. Previous reports [15, 16] suggested a 35% reduction in transfusion rate using IVFe but we set a higher transfusion rate (40%) considering the complexity and severity of cardiac surgery. The sample size calculation was based on superiority analysis under the hypothesis that all data was normally distributed data. We set the significance level at 0.05, the power at 80%, and the effect size was 0.5. A two-sided test was used and consequentially 97 patients were need for each group; however, we set each group as 107 considering a 10% dropout rate (total 214).