PREDICTION OF A FATAL ATRIAL-FIBRILLATION IN PATIENTS WITH ASYMPTOMATIC WOLFF-PARKINSON-WHITE PATTERN

Paroxysmal atrial fibrillation (PAF) in patients with manifest WPW syndrome can be a life-threatening arrhythmia by deterioration into ventricular fibrillation. In patients with asymptomatic WPW pattern, the first PAF may lead to ventricular fibrillation or sudden death. Therefore, the purpose of this study was to predict a fatal PAF in patients with asymptomatic WPW pattern. The patient population was divided into two groups: (1) 145 patients with manifest WPW syndrome, excluding intermittent ones (32 with an episode of PAF, 49 with AV reciprocating tachycardia alone, and 64 without any episode of paroxysmal tachyarrhythmia), and (2) mixed group of patients with and without WPW syndrome (36 with an episode of PAF and 66 without PAF). The results were as follows: (1)(a) out of 32 patients with WPW syndrome and PAF, 8 patients were observed to have both the shortest preexcited R-R interval of less than 200 msec during PAF and the shortest antegrade effective refractory period of the accessory pathway (ERP-AP) of less than 250 msec, 7 of whom had dizziness or syncope during PAF and 2 died suddenly during the follow-up period; (b) 21 (32.8%) out of 64 patients with asymptomatic WPW pattern showed the shortest antegrade ERP-AP < 250 msec; (2) patients with PAF had a higher tendency to develop repetitive atrial firing (RAF), as well as fragmented atrial activity (FAA), which were induced using programmed atrial stimulation. If a positive test result was defined as the induction of RAF and FAA, the positive predictive value was 63% and negative predictive value 79%. In conclusion, (1) having both the shortest R-R interval of less than 200 msec during PAF and the shortest antegrade ERP-AP of less than 250 msec might be a criterion for the identification of high risk in patients with WPW syndrome and PAF, (2) electrophysiologically revealed latent risk was observed in about one third of the patients with asymptomatic WPW pattern, in whom the ERP-AP was very short, (3) in these asymptomatic patients with combined RAF and FAA, the positive test result of atrial vulnerability might be of use to predict a fatal atrial fibrillation.