EVALUATION OF THE ELECTROPHYSIOLOGIC PROPERTIES OF ASYMPTOMATIC WOLFF-PARKINSON-WHITE SYNDROMES - COMPARISON WITH SYMPTOMATIC WOLFF-PARKINSON-WHITE SYNDROMES

The aim of this study was to compare the electrophysiologic properties of asymptomatic Wolff-Parkinson-White (WPW) syndromes with those of symptomatic WPW, and in particular the anterograde refractory period of the accessory tract and atrial vulnerability. This retrospective study involved 171 patients with WPW seen in their surface electrocardiogram, untreated, having undergone standard invasive electrophysiologic investigation. These patients were divided into two groups : group I consisting of 42 asymptomatic patients and group II consisting of 129 asymptomatic patients. 1) The mean anterograde refractory period (mean ARP) did not differ statistically between group I (330 +/- 97 msec) and group II (311 +/- 110 msec). The mean minimum interval between two preexcited complexes during atrial fibrillation (mean RR min) did not differ statistically between group I (313 +/- 80 msec) and II (300 +/- 105 msec). The mean retrograde refractory period (mean RRP) was significantly (p < 0.001) longer in group I (416 +/- 126 msec) than in group II (307 +/- 75 msec). 2) A reciprocal tachycardia was induced in 95 % of cases in group II (122 patients) as compared with 9.5 % of cases in group I (4 patients), with a very significant (p < 0.001) difference. Atrial fibrillation was induced in 24 % of cases in group I (10 patients) and 34 % of cases in group II (44 patients), the difference not being significant. 3) The incidence of potentially serious forms did not differ statistically between groups I and II. Nine patients in group I (21.4 %) and 49 patients in group II (38 %) had rapid anterograde conduction in the accessory tract (ARP or RR less-than-or-equal-to 250 msec). Six patients of group I (14.3 %) and 24 patients of group II (19 %) had both rapid anterograde conduction and atrial vulnerability. In conclusion, there is no way of differentiating between asymptomatic and symptomatic WPW syndromes with regard to the incidence of potentially serious forms. This finding is felt to justify the routine detection of << high risk >> patients by electrophysiologic evaluation of indicators of severity.