The severity and prognosis of idiopathic ventricular arrhythmias in childhood were studied in 24 patients (12 boys, 12 girls) with an average age of 8 years at the time of diagnosis of the
arrhythmia. Investigations included clinical assessment and analysis of basal ECG (morphology of the arrhythmias) and dynamic recordings (Holter and exercise stress testing). The
clinical course was followed for an average of 3.8 years. The patients were classified in two groups: monomorphic arrhythmias (Group I) and polymorphic arrhythmias (Group II). Group I was divided into 4 subgroups: isolated
ventricular extrasystoles (IA), 11 patients;
ventricular extrasystoles with bursts of
ventricular tachycardia (IB), 6 patients; sustained
ventricular tachycardia without intercritical
extrasystoles (IC), 1 patient;
accelerated idioventricular rhythm (ID), 2 patients. Subgroups IA, IB and ID were characterised by the absence of symptoms, the disappearance of the
arrhythmia on exercise, the decreased efficacy of
antiarrhythmic drugs and an excellent prognosis. Therapeutic abstention was the rule in these patients. Patients in Group IC were characterised by the variability of their symptoms, the absence of exercise induced arrhythmias, the need for treatment in most cases and a good long-term prognosis. Group II was divided into 2 subgroups:
adrenergic polymorphic
ventricular tachycardia (IIA), 2 patients, and non-
adrenergic polymorphic
ventricular tachycardia (IIB), 2 patients. Patients in Subgroup IIA were characterised by
syncope on exercise or emotion, the need for betablocker
therapy which considerably improved the patients symptoms but which did not usually prevent
sudden death.(ABSTRACT TRUNCATED AT 250 WORDS)