Ahnve 1980.

Study characteristics
Methods	Randomised clinical trial at a single site in Sweden between May 1977 and December 1978
Participants	111 participants younger than 70 years of age who had had a recent acute myocardial infarction and were in sinus rhythm when discharged alive from the hospital were included in the trial Male:female = 88:23 Mean age = 60 years Exclusion criteria: complete bundle branch block, severe heart failure, hypotension, bronchial asthma
Interventions	Experimental group: metoprolol (100 mg b.i.d.) (n = 59) Control group: placebo (n = 52) Co‐intervention: not described Excluded medication: not described
Outcomes	Outcomes: fatal + non‐fatal myocardial reinfarction and sudden death Time points reported: 6 and 12 months after the acute event
Notes	Email was not found Mean time from myocardial infarction to randomisation is not reported; however, participants had to be discharged alive from the hospital after acute myocardial infarction to be included. Hence, we assume participants were randomised in the non‐acute phase after myocardial infarction 10 patients died; however, only the number of sudden deaths is reported for each group (3 in metoprolol group, 4 in placebo group). Reported data on the 10 deaths was found in Yusuf 1985, where the trial was included and was reported with the help of personal communication MACE was calculated and was reported as a composite of 'non‐fatal reinfarction + sudden death (presumably arrhythmic or cardiac rupture)' Study was funded by grants from the Swedish National Association against Heart and Chest Diseases and the Hässle Company (pharmaceutical company)
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	"Prior to discharge the patients were stratified and randomised"
Allocation concealment (selection bias)	Unclear risk	Not described
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Described as double‐blinded; however no further information was reported
Blinding of outcome assessment (detection bias) All outcomes	Low risk	"Salient clinical data were registered by code on special charts and transferred to punch‐cards for computer analysis. The QTc intervals were measured retrospectively by one of us (S.A.) without knowledge of the patients' clinical data"
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Not described
Selective reporting (reporting bias)	Unclear risk	No protocol could be found; however mortality was reported
Other bias	Low risk	No other biases were found