Here is the design of a clinical trial:

Official Title: Lenient Rate Control Versus Strict Rate Control for Atrial Fibrillation. The Danish Atrial Fibrillation (DanAF) Randomised Clinical Trial

Included conditions:
- Atrial Fibrillation, Persistent
- Atrial Fibrillation Chronic
- Atrial Fibrillation

Study Armgroups:
- {'label': 'Lenient rate control', 'type': 'EXPERIMENTAL', 'description': 'Treating physicians will target a resting heart rate between 80 and 110 beats per minute on a 12-lead resting ECG measured over 1 minute after 5 minutes of rest.', 'interventionNames': ['Other: Rate control']}
- {'label': 'Strict rate control', 'type': 'ACTIVE_COMPARATOR', 'description': 'Treating physicians will target a resting heart rate a mean resting heart rate \\< 80 bpm on a 12-lead resting ECG measured over 1 minute after 5 minutes of rest.', 'interventionNames': ['Other: Rate control']}

Interventions:
- {'type': 'OTHER', 'name': 'Rate control', 'description': 'Treatment will be provided according to current guidelines and as such the algorithm for treatment will be differentiated based on the status of left ventricular ejection fraction. For participants with reduced left ventricular ejection fraction, beta-blockers (metoprolol and bisoprolol) will be the primary therapy. Secondary therapies may include digoxin or amiodarone. For participants with preserved left ventricular ejection fraction, the primary therapy will be beta-blockers (metoprolol and bisoprolol) or non-dihydropyridine calcium-channel blockers (verapamil) with secondary therapy consisting of digoxin or amiodarone. Pacing therapies, alone or with atrioventricular node ablation, are utilised as indicated in the view of the treating physician.', 'armGroupLabels': ['Lenient rate control', 'Strict rate control']}

Primary Outcomes:
- {'measure': 'Short Form-36 (SF-36) physical component score', 'timeFrame': 'After 1 year'}

Please estimate the sample size based on the assumption: 
power of 80%, significance level of 5%
Sample size: quality of life using the SF-36 questionnaire (physical component score)
          Using a minimal important difference of 3 points on the physical component score, an SD of 10, power of 80% and a significance level of 5% and a total of 350 participants will be needed.17 39 40 Based on this sample size, we have estimated the power of all remaining outcomes (see online supplemental file 5).
          
            10.1136/bmjopen-2020-044744.supp5
            Supplementary data