Dunn 1985.

Study characteristics
Methods	Parallel design (2 arms) Country: Northern Ireland Follow‐up period: not reported
Participants	Randomly assigned: N = 425 Withdrawal from study: 7.3% (31/425) Eight participants who had a proved myocardial infarction did not enter the study (page 354). Twenty‐three patients did not fulfil entry criteria Analysed, % (n/N) Lidocaine group: 51.49 (207/402) Placebo (normal saline) group: 48.50 (195/402) Age: 56 years (both groups); not reported by comparison groups Gender, male, % (n/N) Total group: 71.14 (286/402) By comparison group: not reported Inclusion criteria Suspected acute myocardial infarction Age < 70 years Assessed within 6 hours of onset of symptoms Exclusion criteria (≥ 1 of the following was present) Heart rate ≤ 50 bpm Heart rate ≥ 100 bpm after pain relief Systolic blood pressure ≤ 80 mmHg after pain relief Acute pulmonary oedema Second‐degree or complete atrioventricular block Sustained ventricular tachycardia Ventricular fibrillation Prior therapy with antiarrhythmic agents but excluding beta‐blockers or digoxin
Interventions	Lidocaine, 300 mg, intramuscular route, followed by lidocaine, 100 mg, by intravenous bolus over 3 minutes Placebo: normal saline (equivalent volume of normal saline)
Outcomes	Incidence of ventricular fibrillation, sustained ventricular tachycardia, warning arrhythmias Incidence of central nervous system side effects, hypotension, tachycardia, bradycardia, asystole
Notes	Sample size calculation a priori: not reported Sponsor: not reported Trial conduction dates: November 1981 to February 1983
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	" ...we undertook a double‐blind randomised trial..." (page 354) Insufficient information about the sequence generation process to permit judgement of ‘low risk’ or ‘high risk’
Allocation concealment (selection bias)	Unclear risk	Insufficient information to permit judgement of ‘low risk’ or ‘high risk’
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Insufficient information to permit judgement of ‘low risk’ or ‘high risk’
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Insufficient information to permit judgement of ‘low risk’ or ‘high risk’
Incomplete outcome data (attrition bias) All outcomes	Low risk	Withdrawals from study: 7.3% (31/425) Eight patients who had a proved myocardial infarction did not enter the study (page 354) Twenty‐three patients did not fulfil entry criteria Heart rate > 110 bpm before receipt of trial drug: 9 Taking oral antiarrhythmic (mexiletine, amiodarone) before the study: 7 Age > 70 years: 3 Delay in time > 6 hours: 1 Other reasons: 2 Comment: Trial authors did not report lost participants by comparison group
Selective reporting (reporting bias)	Low risk	The study protocol is not available, but it is clear that published reports describe all expected outcomes, including those that were pre‐specified (convincing text of this nature may be uncommon)
Other bias	High risk	Bias of presentation data, design bias (Porta 2008)