Randomised controlled trials (RCTs) which compared ICD with medical therapy in patients resuscitated after cardiac arrest, with documented or symptomatic sustained ventricular tachyarrhythmia, or with depressed ventricular function deemed to be at high risk of developing lethal cardiac arrhythmia, were eligible for inclusion. The primary outcome was all cause mortality.
It appears that both primary and secondary prevention studies were included. Number of participants in the included trials ranged from 103 to 2,521. Mean age of the participants ranged from 58 to 66 years. Mean ejection fraction of the trial participants ranged from 0.21 to 0.45.