Four RCTs were included (n= 143 evaluable patients).
One study was considered to be high quality. One study described the randomisation method, one described intention-to-treat analysis and no patients were lost to follow-up. None of the studies were blinded.
Procainamide was evaluated in one study (n=14), flecainide in one study (n=15), amiodarone in two studies (n=26), magnesium in one study (n=18), verapamil in one study (n=15), diltiazem in one study (n=27) and esmolol in one study (n=28).
Success rates with amiodarone were 50 per cent to 70 per cent at two hours and 50 per cent at 24 hours (2 studies).
One study reported no significant difference in conversion rates between amiodarone and procainamide at 12 hours (70 per cent versus 71 per cent).
One study reported a higher conversion rate with magnesium compared to amiodarone in patients who also received digoxin (77 per cent versus 50 per cent, p not reported).
One study reported a significantly increased conversion rate at one hour with flecainide compared to verapamil (80 per cent versus 33 per cent, p<0.001).
One study reported a significantly higher conversion rate at two hours with esmolol compared to diltiazem (68 per cent versus 33 per cent, p<0.05) but no significant difference at 12 hours (85 per cent versus 62 per cent, p=0.116).
Adverse events
Amiodarone was associated with clinically significant hypotension in two of 24 patients and death in another two of 24 patients. Flecainide was associated with significant prolongation of QRS interval leading to premature ventricular contraction in one of 15 patients and brief hypotension in two of 15 patients, verapamil with hypotension in three of 15 patients and diltiazem with hypotension in 12 of 30 patients. Drugs had to be withdrawn in two patients (one each for esmolol and diltiazem).