Flec‐SL 2012.

Methods	RCT Open‐label Loss to follow‐up reported: yes
Participants	Persistent AF with indication for cardioversion (mean duration: 20 months). n = 362 Men: 66% Age (mean): 64 (SD 10) years Structural heart disease: NS LAD: 46 mm. LVEF: NS
Interventions	Flecainide 200–300 mg/day vs no treatment Method of AF cardioversion: pharmacological 20%, electrical 80% Warfarin discretionary
Outcomes	At 6 months: Mortality Proarrhythmia Stroke, embolism AF recurrence
Notes	A third group of participants randomised to flecainide for only 3 months was not included in the review.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Random numbers table.
Allocation concealment (selection bias)	Low risk	Allocation by a distant central office.
Blinding (performance bias and detection bias) All outcomes	High risk	Open‐label trial.
Incomplete outcome data (attrition bias) All outcomes	Low risk	All withdrawals and dropouts of participants well described. Missing outcome data balanced across intervention groups.
Selective reporting (reporting bias)	Low risk	All of the study's prespecified outcomes were reported in the prespecified way.
Other bias	Low risk	No other bias apparent.