Clinical experience with propafenone for cardiac arrhythmias in the young

Seventy-two children were treated with propafenone between 1980and 1990. The mean age was 34 months (range 0.192). Arrhythmiasincluded atrioventricular re-entry tachycardia in 32 patients(44%), atrial flutter in 16 (22%), atrial or junctional ectopictachycardia in 10 (14%), atrial re-entry tachycardias in three(4%) and ventricular arrhythmias in 11 patients (16%). The efficacyof oral treatment was good in patients with atrio-ventricularre-entry tachycardia (80%), atrial flutter (71%) and atrialectopic tachycardia (83%); it was poor in ventricular arrhythmias(40%). The mean oral dose was 13.5 mg. kg^–1. day^–1. Dosageand serum levels of propafenone did not differ whether the patientswere treated successfully or not. No correlation between dosageand serum level was observed. Intravenous propafenone administrationwas only partially successful in suppressing supraventriculartachycardias (6 of 11 patients). The presence of a congenital heart defect and the time of onsetof the arrhythmias had a significant influence on the efficacyof propafenone. Better results were observed in patients withnormal hearts and in whom onset of arrhythmia was pre-natal(success 80%) as well as in patients with arrhythmias seen earlyafter surgery for congenital heart defects (success 87%). Success(65%) was also observed in patients without congenital heartdefects and postnatal onset of supraventricular arrhythmias.Patients with ventricular or supraventricular arrhythmias lateafter corrective surgery showed the poorest response (31%).