High incidence of clinical and subclinical toxicity associated with amiodarone treatment of refractory tachyarrhythmias.

Amiodarone has been hailed as the most effective single antiarrhythmic drug for treatment of refractory supraventricular and ventricular arrhythmias. However, questions continue to arise about its long-term potential toxicity and true efficacy rates. We, therefore, reviewed our experience with 78 patients, mean age 59 +/- 14 years, with drug refractory tachyarrhythmias treated with amiodarone. Sixty-two patients were treated for recurrent ventricular tachycardia or ventricular fibrillation, 4 for complex ventricular ectopy and 12 for supraventricular tachyarrhythmias. Patients have been treated for a mean of 9.9 months (range, 1 day to 39.1 months); 34(55%) continued to be successfully treated for ventricular tachycardia/ventricular fibrillation, 2 (50%) for complex ventricular ectopy and 5 (42%) for supraventricular tachyarrhythmias. Amiodarone toxicity was frequent, occurring in 57/72 patients (79%) who were treated for more than one week. Adverse effects led to drug discontinuation in 15 (21%), 3 because of pulmonary toxicity (1 in combination with neuropathy and another with drug-induced hepatitis); 2 because of chemical hepatitis; 1, confusion; 6, neuropathy; 2, arrhythmia exacerbation; 2, symptomatic bradycardia; and 1 because of impotence. Of the 62 ventricular tachycardia/ventricular fibrillation patients who were treated with amiodarone, 8 (13%) expired: 4 died suddenly and 4 from documented ventricular tachycardia during treatment. In contrast, of 16 patients who had discontinued amiodarone because of initial adverse effects or drug failure and were treated with alternative antiarrhythmic medications, 5 (31%) died suddenly. In conclusion, amiodarone appears to be fairly effective in high risk patients with refractory cardiac tachyarrhythmias but results in a rather high incidence of adverse effects in long-term follow-up.(ABSTRACT TRUNCATED AT 250 WORDS)