Abel 1983.

Methods	Quasi‐randomized, open‐label trial; beta‐blocker versus standard care
Participants	Overall: 91 participants; beta‐blocker: 41 participants; standard care: 50 participants (100% of participants were taking beta‐blockers preoperatively) Mean age: 56.6 years Percentage of female participants: 17
Interventions	Participants received either propranolol or standard care; treatment was initiated during surgery and was continued until hospital discharge
Outcomes	Primary outcomes: supraventricular arrhythmias; secondary outcomes: ventricular arrhythmias, myocardial infarction, hospital mortality
Notes	Type of surgery: elective coronary artery bypass grafting (CABG)
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	High risk	Quasi‐randomization (last digit of hospital record number)
Allocation concealment (selection bias)	High risk	See above
Blinding of participants (performance bias) All outcomes	High risk	Open‐label trial
Blinding of doctors/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	High risk	9 withdrawals in beta‐blocker group due to bradycardia (2), severe hypotension (3), preoperative myocardial infarction (2), biventricular failure (1), and cardiac arrest (1)
Intention to treat analysis	High risk	Participants were not analysed as randomly assigned
Selective reporting (reporting bias)	Low risk	Not detected
Other bias	Low risk	Not detected