Amiodarone in the treatment of cardiac arrhythmias in children: one hundred thirty-five cases.

Oral amiodarone was given to 135 children (mean age, 10.2 years) for a mean duration of 4.1 months (range, 1 day to 6 years) for mainly idiopathic (25%) and postoperative (61%) arrhythmias. Complete ECG control or partial ECG control with clinical improvement was obtained in 60% and 33% of cases, respectively, regardless of the arrhythmia location (atrial 69%, junctional 16%, and ventricular 15%), mechanism, resistance (55%) or sensitivity (45%) to other drugs, and presence of cardiomegaly (40%) or clinical signs of heart failure (27%). The only factor favoring improvement was a short history (< 2 months in 54%). The rapid onset of drug effect (4.1 days), the early relapses after treatment discontinuation (3.3 weeks), and the absence of side effects due to drug accumulation reflect a faster metabolism than that in adults, with no cardiac toxicity and a low incidence of thyroid dysfunction (2 hyperthyroid, 1 hypothyroid).