Amiodarone in the management of patients with ventricular tachycardia and ventricular fibrillation.

Fifty-eight patients with symptomatic ventricular tachycardia (VT) or ventricular fibrillation (VF) were treated with amiodarone. All had clinical episodes of VT/VF or inducible VT during electropharmacologic testing despite treatment with maximum-tolerated doses of conventional antiarrhythmic agents. Chronic treatment with amiodarone was begun at a dose of 800-1000 mg per day. Thirty-two patients were also treated with a previously ineffective conventional agent. Thirty patients underwent programmed ventricular stimulation after 2.6 +/- 1.7 months (mean +/- S.D.) of treatment with amiodarone at a mean daily dose of 588 +/- 155 mg. VT was induced in 25 patients (sustained in 20, nonsustained in five). Seventeen patients had a recurrence of VT or VF after 0.5-9 months of treatment with amiodarone (fatal in seven, non-fatal in 10). Forty-one patients (71%) had no recurrence of symptomatic VT or VF while being treated with amiodarone (mean follow-up period, 17.1 +/- 12.4 months). Among the 25 patients who had inducible VT with programmed ventricular stimulation while being treated with amiodarone, 19 patients (76%) have had no recurrence of symptomatic VT or VF over a follow-up period of 21.5 +/- 7.3 months. Ambulatory electrocardiographic recordings obtained after one week of treatment with amiodarone were not helpful in predicting clinical response. Twenty-two patients (38%) developed ataxia and/or an intention tremor which improved with a decrease in the amiodarone dose. Amiodarone, either by itself or in combination with conventional antiarrhythmic drugs, has a significant therapeutic effect in high risk patients with refractory VT. The finding of inducible VT during electropharmacologic testing in patients taking amiodarone does not preclude a favorable clinical response. Neurologic toxicity is common in patients treated with 600-800 mg per day of amiodarone.