Silverman 1982.

Methods	Quasi‐randomized trial, parallel design
Participants	Total number of randomized participants: 100 Inclusion criteria: scheduled for CABG surgery without additional cardiac surgical procedures Exclusion criteria: not reported Type of surgery: elective CABG Baseline characteristics Intervention group (propranolol) Age, mean (SD): 55.2 (± 1.7) years Gender, M/F: 48/2 History of MI, %: 56 History of hypertension, %: 44 Preoperative use of beta‐blockers, %: 100 Control group (standard care) Age, mean (SD): 58.2 (± 1.5) years Gender, M/F: 45/5 History of MI, %: 64 History of hypertension, %: 54 Preoperative use of beta‐blockers, %: 100 Country: USA Setting: single centre; hospital
Interventions	Intervention group (propranolol) Randomized, n = 50; losses = 0; analysed, n = 50 (use of ITT analysis was not reported) Details: existing dose of propranolol tapered the day before surgery or maintained at current dose if participant had previously unstable angina or significant left main stenosis. 10 mg orally or via nasogastric tube started on 1st postoperative day, continued until discharge Control group (standard care) Randomized, n = 50; losses = 0; analysed, n = 50 (use of ITT analysis was not reported) Details: no additional agent
Outcomes	Outcomes measured/reported by study authors: supraventricular arrhythmias (to include AF and atrial flutter); perioperative MI, bradycardia or bronchospasm (necessitating discontinuation of study medication) Outcomes relevant to the review: AF and atrial flutter; perioperative MI; bradycardia and bronchospasm (see notes below)
Notes	Funding/declarations of interest: not reported Study dates: not reported Note: study authors reported that no participants developed bradycardia or bronchospasm sufficient to discontinue medication. We did not include these data in analysis because we could not be certain whether the outcome was measured only in the intervention group
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	High risk	Quote: "Randomization was by birthdate" Comment: quasi‐randomization
Allocation concealment (selection bias)	High risk	See above
Blinding of participants and personnel (performance bias) All outcomes	High risk	Open‐label trial
Blinding of outcome assessors (detection bias) All outcomes	High risk	Open‐label trial
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	High risk	Either group were given digoxin and propranolol to control supraventricular tachycardias ‐ this affected 6 participants in the control group and 5 participants in the intervention group. This may influence outcome data