Kuhlkamp 2000.

Methods	RCT Double‐blind Loss to follow‐up reported: yes
Participants	Persistent AF lasting 2 days to 1 year (mean duration: 3 months). n = 394 Men: 70% Age (mean): 60 (range 24–86) years Structural heart disease: 36%. LAD: 42 mm. LVEF: 64%
Interventions	Metoprolol 100 mg/day vs placebo Method of AF cardioversion: pharmacological 18%, electrical 82% Warfarin discretionary
Outcomes	At 6 months: Mortality Proarrhythmia Adverse effects AF recurrence
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer‐generated randomisation list.
Allocation concealment (selection bias)	Low risk	Central allocation after inclusion.
Blinding (performance bias and detection bias) All outcomes	Low risk	Double‐blind study. Quote: "The placebo tablets were identical in size, weight, colour, and taste to the metoprolol CR/XL [controlled‐release/extended release] tablets".
Incomplete outcome data (attrition bias) All outcomes	Low risk	Withdrawals and lost to follow‐up were balanced between groups and well described.
Selective reporting (reporting bias)	Low risk	All prespecified outcomes and expected outcomes of interest were well reported.
Other bias	Low risk	No other bias apparent.