Twenty-five studies were included (number of participants not reported). There were eleven RCTs, seven studies with concurrent controls, two studies with retrospective controls, two uncontrolled studies and six studies not relating to the review population. Six RCTs were categorised as good and five were classed as fair. Of the non-randomised studies, 16 were categorised as fair quality and one as poor quality.
Amiodarone: Two RCTs found improved survival to admission with amiodarone compared to lidocaine. Two non-randomised prospective studies found no difference in survival using the same comparison.
Lidocaine: Results for lidocaine were mixed. One non-randomised prospective study and one retrospective review suggested increased short term survival with lidocaine. Three retrospective studies indicated lower survival to admission with lidocaine. Two studies found that lidocaine was inferior to amiodarone in short-term survival.
Magnesium: Magnesium did not demonstrate improved return of spontaneous circulation in three RCTs.
Procainamide: Results for procainamide were mixed. One retrospective study found increased one hour survival, and one retrospective study found decreased survival with procainamide. An RCT was also included in this analysis, but it appeared to be unrelated to the review population.
Bretylium: One RCT found improved survival with bretylium compared to placebo. Results from two RCTs found that survival rates with bretylium and lidocaine did not significantly differ.
The results from studies with different populations from the review question were also reported.