G017 Factors associated with the induction of antidromic tachycardia in the wolff-parkinson-white syndrome

Atrioventricular reentrant tachycardia (AVRT) is the most frequent inducible tachycardia in patients with a Wolff-Parkinson-White syndrome (WPW). The incidence and the causes of the induction of antidromic tachycardia (ATD) are unknown. The purpose of the study was to determine the data of patients with a WPW and with inducible ATD.Methods605 patients had a WPW and tachycardias (n=312) or syncope (n=85); other patients were asymptomatic (n=208). Electrophysiological study (EPS) was systematic. In control state (CS), the higher rate conducted through accessory pathway (AP) was measured; programmed atrial stimulation with 1, 2 extrastimuli was performed to induce a tachycardia. Isoproterenol (0.02 to 1μg. min-1) was infused and the protocol was repeated.ResultsATD was induced in 44 patients (7 %) (group I). Their data were compared to those of remaining patients (group II). Group I differed from group II by the following data: Female sex was less frequent in group I (29.5 %) than in group II (47 %); AP was more frequently left sided in group I (54.5 %) than in group II (38 %) (p<0.05). AVRT was induced less frequently in group I (34 %) than in group II (57 %) (p<0.01); maximal rate conducted through AP was higher in group I (215±52b/min) than in group II (189±61) in control state, and after isoproterenol (281±57 in group I vs 236±61 in group II) (p