Here is the design of a clinical trial:

Official Title: Phase II Clinical Trial Testing the Safety of a Humanized Monoclonal Antibody Anti-CD20 in Patients With Heart Failure With Reduced Ejection Fraction

Included conditions:
- Heart Failure With Reduced Ejection Fraction

Study Armgroups:
- {'label': 'Interventional Group', 'type': 'EXPERIMENTAL', 'description': "For this trial, HMA-CD20 will be given as an intravenous infusion of 1000 mg I.V twice in a month separating them by fourteen days starting at the baseline visit. The dose for both HMA-CD20 dosages willbe identical at the screening visit after the participant's eligibility has been established, and it will remain thesame for both infusions. The standard dose for HMA-CD20 is 1,000 mg per intravenous infusion on day 1 and day 15.", 'interventionNames': ['Drug: Rituximab']}

Interventions:
- {'type': 'DRUG', 'name': 'Rituximab', 'description': 'Rituximab will be studied in patients with HFrEF, and verify the patients safety.', 'armGroupLabels': ['Interventional Group']}

Primary Outcomes:
- {'measure': 'Incidence of Rituximab Emergent Cardiovascular Adverse Events', 'description': 'The investigators analyze the safety of rituximab based on the occurrence of cardiovascular adverse events such as arrhythmia, worsening of symptoms and acute coronary syndromes.', 'timeFrame': '6 months'}

Please estimate the sample size based on the assumption: 
A power of 80% and an alpha score of 0.05 were considered.
Sample size
        We considered a convenience sample of 10 patients from our heart failure clinic since the previously reported incidence of acute coronary syndromeÂ (ACS) and atrial and ventricular arrhythmias with the use of rituximab isÂ <0.1% and 7.6%, respectively.8 Regarding the worsening of left ventricle ejection fractionÂ (LVEF) attributed to rituximab, the incidence is limited to case reports only, wherefore it is impossible to precisely determine the incidence.9 Moreover, with the strategic safety measures that we will take before, during and following the rituximab administration, we aim to reduce the risk of potential cardiovascular adverse eventsÂ (AEs). However, the sample size required; considering a power of 80% and an alpha score of 0.05, obtained by probabilistic methods, ranges from 321 to 26â091 subjects to enrol, which would, unfortunately, be out of our reach.