Clinical and electrophysiologic characteristics in patients with Wolff-Parkinson-White pattern

(1) To obtain a relation between clinical and electrophysiologic characteristics in patients with Wolff-Parkinson-White pattern. To evaluate the atrial vulnerability for inducing atrial fibrillation and its relation to the electrophysiologic protocol phase. (3) To study the effects of flecainide on the treatment of induced sustained supraventricular arrhythmias.

Department of Cardiology at Santa Marta Hospital.

An electrophysiologic testing was performed in twenty-three consecutive patients aged from 14 to 55 years, with Wolff-Parkinson-White (WPW) pattern on ECG. Two groups of patients were considered: group I with 12 asymptomatic or nearly asymptomatic patients; group II with 11 symptomatic patients. The parameters studied were the anterograde effective refractory period of the accessory pathway, the number of patients with different types of supraventricular tachycardias (SVT), the relation between the stimulation protocol phase (scanning/DDT/burst) and the occurrence of atrial fibrillation, and the effects of the flecainide on the treatment of induced sustained supraventricular arrhythmias.

Statistically significant differences were obtained between group I and II concerning the number of patients in whom induced atrial fibrillation with conduction by the accessory pathway and RR < or = 250 msec was found (0 vs 6, p = 0.0045). No differences were obtained among the anterograde refractory period, the induction of atrial fibrillation independently of the type of atrioventricular conduction, and the induction of atrioventricular reentrant tachycardia and or atrial flutter. The induction of atrial fibrillation was attained during the Scanning/DDT protocol phase in 7 patients in whom this arrhythmia was found with conduction by the accessory pathway and in 2 without preexcitation. All the induced sustained supraventricular arrhythmias were converted by intravenous flecainide.

(1) Only the symptomatic patients have a high risk profile which suggest that electrophysiologic testing do not need to be performed in those with no symptoms. (2) As atrial vulnerability is higher in patients with induced atrial fibrillation and conduction by the accessory pathway, a more intensive ambulatory control seems to be necessary. (3) The results of intravenous flecainide administration on the treatment of sustained induced supraventricular arrhythmias, advocate its use during the electrophysiologic procedures in patients with ventricular preexcitation and WPW pattern.