Clinical efficacy of amiodarone in treatment of recurrent ventricular tachycardia and ventricular fibrillation.

The clinical antiarrhythmic efficacy of amiodarone treatment was examined in 196 patients with recurrent ventricular tachycardia (VT) or ventricular fibrillation (VF) resistant to other antiarrhythmic drugs. Patients had received a mean of 4.4 +/- 1.9 unsuccessful drug trials over a mean of 15.2 months prior to amiodarone treatment of recurrent VF in 57 patients; recurrent, sustained VT in 95 patients; and recurrent, nonsustained VT in 44 patients. Amiodarone dosage during the first 2 to 4 weeks of treatment was 800 to 1600 mg/day. During long-term follow-up, amiodarone dosage was reduced to 200 to 600 mg/day, based on the control of arrhythmia and patient tolerance. Electrophysiologic studies were performed prior to and after 2 or more weeks of amiodarone treatment. After a mean follow-up of 16.2 +/- 13.0 months, 126 (64%) of 196 patients continued successful treatment with amiodarone. At electrophysiologic study, amiodarone prevented VT induction in 13 patients, and although VT was induced in 101 patients, 80 patients continued treatment for 14.2 months without recurrence of spontaneous VT. Amiodarone treatment was discontinued because of recurrent VT in 22 patients, sudden cardiac death in 15 patients, adverse effects in 12 patients, and noncardiac death in 21 patients. In nine patients, recurrent VT/VF appeared related to amiodarone-induced exacerbation of arrhythmia. Pulmonary toxicity occurred in seven patients, and 19 patients developed blue skin discoloration. Other adverse effects were usually dosage related. In summary, amiodarone was a highly effective antiarrhythmic drug, but at the dosages employed, the risk of significant adverse effects warrants careful surveillance during treatment.