Long-term efficacy and toxicity of high-dose amiodarone therapy for ventricular tachycardia or ventricular fibrillation.
Amiodarone was administered to 154 patients who had sustained, symptomatic ventricular tachycardia (VT) (n = 118) or a cardiac arrest (n = 36) and who were refractory to conventional antiarrhythmic drugs. The loading dose was 800 mg/day for 6 weeks and the maintenance dose was 600 mg/day. Sixty-nine percent of patients continued treatment with amiodarone and had no recurrence of symptomatic VT or ventricular fibrillation (VF) over a follow-up of 6 to 52 months (mean +/- standard deviation 14.2 +/- 8.2). Six percent of the patients had a nonfatal recurrence of VT and were successfully managed by continuing amiodarone at a higher dose or by the addition of a conventional antiarrhythmic drug. One or more adverse drug reactions occurred in 51% of patients. Adverse effects forced a reduction in the dose of amiodarone in 41% and discontinuation of amiodarone in 10% of patients. The most common symptomatic adverse reactions were tremor or ataxia (35%), nausea and anorexia (8%), visual halos or blurring (6%), thyroid function abnormalities (6%) and pulmonary interstitial infiltrates (5%). Although large-dose amiodarone is highly effective in the long-term treatment of VT or VF refractory to conventional antiarrhythmic drugs, it causes significant toxicity in approximately 50% of patients. However, when the dose is adjusted based on clinical response or the development of adverse effects, 75% of patients with VT or VF can be successfully managed with amiodarone.
D000368:Aged; D000638:Amiodarone / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D000855:Anorexia / Q000139:chemically induced; D001259:Ataxia / Q000139:chemically induced; D001572:Benzofurans / Q000627:therapeutic use*; D005260:Female; D006323:Heart Arrest / Q000628:therapy; D006801:Humans; D008171:Lung Diseases / Q000139:chemically induced; D008297:Male; D008875:Middle Aged; D009325:Nausea / Q000139:chemically induced; D012008:Recurrence; D013610:Tachycardia / Q000188:drug therapy*; D013959:Thyroid Diseases / Q000139:chemically induced; D013997:Time Factors; D014202:Tremor / Q000139:chemically induced; D014693:Ventricular Fibrillation / Q000188:drug therapy*; D014786:Vision Disorders / Q000139:chemically induced
D001572:Benzofurans; D000638:Amiodarone