Ref (type)	Population	Outcome, Interventions	Results and statistical analysis	Effect size	Favours
Improvement in functional class
[86] Systematic review	Number of people included in analysis not reported 4 RCTs in this analysis	Proportion of people whose function improved by at least 1 New York Heart Association (NYHA) functional class 58% with cardiac resynchronisation therapy (CRT) 37% with usual care Absolute numbers not reported	RR 1.6 95% CI 1.3 to 1.9 Some RCTs included in the analysis compared CRT plus implantable cardiac defibrillators (ICDs) versus ICDs alone	Small effect size	CRT