Eight RCTs (n=1,889 patients) were included in the review.
Three studies were considered to be of a high quality; the others were considered to be of low to moderate quality. Three studies reported the method of randomisation, two reported the method of allocation concealment, and seven provided detailed information concerning the loss to follow-up. Four studies were double-blinded.
Anti-arrhythmic drug therapy versus beta-blockers (3 studies, n=582).
Anti-arrhythmic drug therapy was associated with a significantly lower risk of ICD shock therapy in the one study that evaluated both amiodarone and sotalol (HR 0.42, 95% CI: 0.19, 0.93, p=0.03); there was evidence of statistical heterogeneity for the different drugs (p=0.05; I-squared 73%). Subgroup analysis by type of anti-arrhythmic drug showed a significant reduction with amiodarone (HR 0.27, 95% CI: 0.14, 0.52, p=0.001), but no significant difference between sotalol and beta-blockers.
Class III anti-arrhythmics were significantly more likely to be discontinued (RR 2.57, 95% CI: 1.32, 5, p=0.006; based on 3 studies); there was a significant increase in the discontinuation rate for amiodarone (RR 3.52, 95% CI: 1.57, 7.97, p=0.002). There was a non significant increase in the risk of new onset or worsening heart failure with anti-arrhythmics compared with beta-blockers (RR 1.44, 95% CI: 0.84, 2.46, p=0.18; based on 2 studies).
Anti-arrhythmic drug therapy versus placebo or non-anti-arrhythmic therapy (5 studies, n=1,372).
Compared with control treatment, anti-arrhythmic therapy was associated with a significantly lower risk of all causes of ICD shock therapy (HR 0.67, 95% CI: 0.55, 0.82, p=0.0001).
No significant differences were found for this outcome between azimilide or dofetilide versus placebo. No significant differences were found between the active and placebo groups for discontinuation of therapy or new or worsening heart failure.