Long-term tolerance of amiodarone treatment for cardiac arrhythmias.

For the 5-year period 1979 to 1983, 242 patients were followed up who had received amiodarone treatment, 156 for supraventricular tachycardia (SVT) and 86 for ventricular arrhythmias. Five patients were lost to follow-up overseas; the rest were followed to cessation of therapy, death or recent review for a mean of 24 +/- 15 months. Male/female incidence was 1.8:1 and mean age was 58 years (range 4 to 88). Half the group had impaired left ventricular function. Adverse effects were recorded in 59% of the patients and led to drug withdrawal in 26% of the total group. In contrast, unsuccessful treatment was the cause of drug withdrawal in only 5% of the patients, although an additional 25% stopped taking the drug for various reasons. Actuarial survival for the whole group, and subgroups with SVT and ventricular tachycardia/fibrillation were 66%, 74% and 52%, respectively, at 50 months. For the whole group, the actuarial probability of being alive and continuing with amiodarone therapy was only 19% at 50 months. Thus, although amiodarone was effective, few patients tolerated the drug on a long-term basis. Although amiodarone remains a valuable treatment for patients with ventricular tachycardia, its long-term effectiveness for patients with SVT is less certain.