Atenolol in children with ventricular arrhythmias.

Twenty children and adolescents treated orally with atenolol for chronic paroxysmal ventricular tachycardia (n = 10) or Long QT Syndrome (n = 10) over a 5 year period were retrospectively evaluated to ascertain the efficacy of arrhythmia suppression, the effective dosage, the cardiovascular effects, and the incidence of adverse effects. Patients with paroxysmal ventricular tachycardia were classified by their response to exercise or catecholamines. Atenolol was effective in each patient (n = 5) whose tachycardia was precipitated or exacerbated by exercise or catecholamines when the patient was receiving a dosage of approximately 1.7 mg/kg/day. In those patients (n = 4) in whom exercise or catecholamines either suppressed or had no effect on the tachycardia, none were effectively treated in spite of receiving comparable dosages. Three of these four patients also had structural abnormalities or myocardial dysfunction. Atenolol was effective in treating 4 of 10 patients with long QT syndrome with a dosage of approximately 1.5 mg/kg/day. Six ineffectively treated patients received similar dosages, and four required either additional medication or surgical sympathectomy for persistent syncope. The other two patients died suddenly. Cardiovascular side effects included bradycardia in three patients and hypotension in one. Noncardiovascular effects included mild fatigue (four patients) headache (two), sleep disturbance (two), and difficulty concentrating (one). The medication was discontinued because of side effects in two patients. Atenolol is more likely to be effective in the suppression of paroxysmal ventricular tachycardia in children if the tachycardia is exacerbated by exercise or catecholamines and if the heart is otherwise normal.