Ref (type)	Population	Outcome, Interventions	Results and statistical analysis	Effect size	Favours
Implant safety
[90] Non-systematic review	3078 people 3 RCTs in this analysis	Implant safety and success with cardiac resynchronisation therapy (CRT) with control Absolute results not reported
[86] Systematic review	3203 people 8 RCTs in this analysis	Implant safety and success with CRT with usual care Absolute results not reported	Some RCTs included in the analysis compared CRT plus ICDs versus ICDs alone