Urias 2016.

Methods	RCT, parallel design
Participants	Total number of randomized participants: 84 Inclusion criteria: scheduled for laparoscopic cholecystectomy; without contraindications to the use of metoprolol Exclusion criteria: not reported Type of surgery: laparoscopic cholecystectomy Baseline characteristics not reported. Study authors reported that, "In demographic variables such as sex, age, there were no differences in the study" Country: Mexico Setting: single centre; hospital
Interventions	Intervention group (metoprolol) Randomized, n = 42; losses = 0; analysed, n = 42 Details: 100 mg metoprolol daily, given orally. Time point and duration were not reported in the abstract Control group (placebo) Randomized, n = 42; losses = 0; analysed, n = 42 Details: placebo
Outcomes	Outcomes measured/reported by study authors: HR, ischaemic heart disease; AF; isolated ventricular premature complexes Outcomes relevant to the review: AF
Notes	Funding/declarations of interest: not reported Study dates: not reported Note: study reported as an abstract only
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Not specifed
Allocation concealment (selection bias)	Unclear risk	Not specifed
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Described as double‐blinded placebo‐controlled trial, and we assumed that the anaesthetists were blinded to study groups
Blinding of outcome assessors (detection bias) All outcomes	Unclear risk	Not specifed
Incomplete outcome data (attrition bias) All outcomes	Low risk	No apparent losses
Selective reporting (reporting bias)	Unclear risk	Study authors did not report prospective clinical trial registration or publication of a protocol. It was not feasible to effectively assess risk of reporting bias
Other bias	Unclear risk	Not feasible to assess other risks of bias from the short abstract report