Amiodarone in the treatment of refractory ventricular arrhythmias. Importance and safety of initial high-dose therapy.

Large initial doses of amiodarone hydrochloride for the treatment of ventricular arrhythmias refractory to conventional therapy were demonstrated to shorten the time to achieve control of the arrhythmia. As compared with a lower-dose regimen, the mean time to achieve partial control (suppression of ventricular tachycardia) was 10.6 +/- 5.2 days in the highest-dose group (group C), 9.5 +/- 6.4 days in the medium-dose group (group B), and 16.9 +/- 9.1 days in the lowest-dose group (group A). Complete control (suppression of virtually all ventricular ectopy) was similarly earlier in groups B and C (16.1 +/- 7.5 days and 16.0 +/- 11.3 days, respectively) as compared with group A (31.0 +/- 10.1 days). The final mean dose for long-term treatment was independent of the initial dose schedule (551 +/- 245 mg/day; range, 200 to 1,200 mg/day). The large doses were shown to be well tolerated and without serious side effects.