The ability of invasive electrophysiologic studies to predict future arrhythmic events in patients with minimally symptomatic Wolff-Parkinson-White syndrome is not known. To assess this ability, 42 patients with evidence of atrioventricular (AV) pre-excitation on the surface electrocardiogram underwent electrophysiologic studies and were then followed up as outpatients taking no medications. The patients were classified into three groups on the basis of prestudy symptoms: group I, 15 asymptomatic patients; group II, 10 patients with infrequent symptoms but no documented arrhythmias; and group III; 17 patients with one documented episode of supraventricular tachycardia or atrial fibrillation, or both.
At electrophysiologic study, the number of patients with short anterograde accessory pathway effective refractory periods and rapid ventricular responses during induced atrial fibrillation did not differ statistically among the three groups. During a mean follow-up period of 7.5 ± 4.9 years, 11 of the 42 patients had documented arrhythmias: 2 patients from group II and 2 patients from group III had supraventricular tachycardia and 7 patients from group III had atrial fibrillation. All nine patients from group III with subsequent arrhythmias had had clinical atrial fibrillation before study. No patient from group I had an arrhythmia during follow-up. There were no episodes of ventricular fibrillation or sudden cardiac death during follow-up in any of the patients. The only predischarge variables that correlated with the subsequent occurrence of arrhythmias were a history of documented arrhythmias before electrophysiologic study (p < 0.01) and inducible supraventricular tachycardia at electrophysiologic study (p < 0.05).
From these data it is concluded that 1) patients with AV pre-excitation and a single episode of atrial fibrillation are likely to have recurrent tachyarrhythmias and should be treated; 2) the risk of sudden death in adults with AV pre-excitation but no clinical arrhythmias is probably low; and 3) although measurements of the accessory pathway effective refractory period and minimal pre-excitation cycle length during induced atrial fibrillation have an excellent negative predictive value, the positive predictive value may be too low to warrant their routine use as screening tools in asymptomatic patients.
